Pregnancy Weight Gain Calculator: the Published Range for Your Pre-pregnancy BMI, at This Point in Pregnancy

The recommended total gain for a pre-pregnancy BMI category, from the ranges the Institute of Medicine published in 2009 and the CDC republishes, apportioned to the gestational age you are at rather than compared against a 40-week total — with the first-trimester allowance kept separate from the weekly rate, the Asian-Indian BMI cut-offs shown alongside the standard ones instead of swapped in silently, and the places where the published table does not agree with itself written down rather than smoothed over.

Last updated 1 Oct 2026

These are estimates from dates and measurements, not findings about this pregnancy. A due date is a midpoint with weeks of normal variation either side, and a predicted fertile window is not a reliable way to avoid pregnancy. Nothing here replaces assessment by a midwife or doctor.

Where a gain sits in the published range FOR THIS GESTATIONAL AGE

height, pre-pregnancy weight, current weight and gestational age -> the published range at that point in pregnancy, and the position in it

Height (cm)Used for one thing: to compute the pre-pregnancy BMI that selects which published range applies. The page refuses outside 100 to 220 cm. Height is the input these calculators are least careful about and it matters more than the weight does, because BMI goes as the square of it: at 60 kg, a height typed as 155 instead of 160 moves the BMI from 23.4 to 25.0 and, on the standard cut-offs, moves the reader out of the normal-weight range and into the overweight one — a recommended total that is 4.5 kg lower at the bottom and 4.5 kg lower at the top. Measure it rather than remembering it.

Pre-pregnancy weight (kg)Weight BEFORE this pregnancy, not at the first antenatal visit. The published ranges are indexed on pre-pregnancy BMI and nothing else, so this figure decides which range the page quotes. In practice it is often a recalled number rather than a measured one, and a recalled pre-pregnancy weight tends to be reported low; a first-visit weight taken at, say, 10 weeks already includes part of the gain this page is trying to measure, so using it both raises the BMI and shrinks the apparent gain. If the only figure available is a booking weight, that is what you have — read the output as softer than it looks and say which weight you used.

Current weight (kg)Today’s weight. The difference between this and the pre-pregnancy weight is the gain the page compares against the range. Nothing here is a verdict: a single weighing carries a kilogram or so of noise from clothing, time of day, bladder and bowel, and a published range is a population statement about outcomes, not a measurement of this pregnancy. Set it equal to the pre-pregnancy weight to see the range alone with no comparison attached.

Gestational age — COMPLETED weeksCompleted weeks, the first half of the obstetric “weeks+days” notation: 26 here with 3 in the next field is 26+3, meaning 26 completed weeks and 3 days, which is the 27th week of pregnancy. The distinction is the commonest off-by-one in this arithmetic — “in the 27th week” and “26 weeks” are the same moment, and “27 weeks” is a week later. This page does not compute gestational age; it takes it. If you are working from a last menstrual period or a scan, the due date and gestational age page derives it, and correction for prematurity after birth belongs to the corrected age page in the medical set.

… and days (0 to 6)The days part of weeks+days, 0 to 6. Seven days is a completed week and belongs in the field above. The page converts weeks+days to a decimal number of weeks by adding days/7, so 26+3 is 26.4286 weeks. At the normal-weight pro-rata rate of about 0.41 kg a week this is worth roughly 175 g per day of gestational age, which is smaller than the noise on a single weighing — the days field matters for the arithmetic being right, not for changing the answer much.

Singleton or twinsThe twin ranges are published as PROVISIONAL in the source, which says so in the table itself, and they come with two further caveats this page implements rather than hides. There is no published weekly rate for twins, so the rate-based comparison rows below disappear when twins is selected and only the pro-rata model remains. And there is no 2009 recommendation at all for an underweight twin pregnancy: the 50 to 62 lb figure the CDC prints for that cell is attributed not to the 2009 report but to Luke and colleagues’ 2003 work, which is a different source reached by a different method, and this page flags it when you land on it. Higher-order multiples have no published range anywhere and this page does not offer one.

41%Example

160 cm, 55 kg before pregnancy, 62 kg now, 26+0 weeks, one baby

Apportioning a published total to a gestational age, two ways, and why they disagree

BMI = W₀ / H² · gain G = W_now − W₀ · t = weeks + days/7, capped at 40 · k = (t − 13)/27, floored at 0 · pro-rata model: L(t) = 0.5 + (T_lo − 0.5)k and U(t) = 2.0 + (T_hi − 2.0)k · rate model: L′(t) = 0.5 + r_lo(t − 13) and U′(t) = 2.0 + r_hi(t − 13) · position = 100 (G − L) / (U − L)

W₀, H: pre-pregnancy weight in kg and height in metres. BMI from these two selects which published range applies, and nothing else does
T_lo, T_hi: the published total gain for the category, in kg: 12.5–18, 11.5–16, 7–11.5 and 5–9 for one baby by rising BMI category; 22.7–28.1, 17–25, 14–23 and 11–19 for twins, the first of which is not from the 2009 report
0.5 and 2.0 kg: the first-trimester gain the published ranges assume, stated in the source as a footnote to its own table. It is an allowance for the whole trimester with no weekly rate attached, which is why this page holds the range flat until 13+0
13 and 27: apportioning runs from 13+0 to 40+0, which is 27 weeks. Thirteen is a choice: the first trimester is conventionally the first 13 weeks and 6 days, so 14+0 and 26 weeks is equally defensible and would raise the implied weekly rate by about 4%. Twenty-seven is used because it reconciles the published total and the published weekly rate more closely than 26 does, which is evidence about what the source divided by
r_lo, r_hi: the published weekly rate for the second and third trimesters, in kg/week: 0.44–0.58, 0.35–0.50, 0.23–0.33 and 0.17–0.27 by rising category. Not published for twins, so the rate model is unavailable there
k: the fraction of the apportioning period elapsed. At t = 40 it is exactly 1, so the pro-rata model lands exactly on the published total; at or before 13+0 it is 0 and the range is exactly the first-trimester allowance
position: 0% is the bottom of the range for that gestational age and 100% the top, inclusive at both ends. Negative is below, above 100 is above. The denominator is the width of the range, which grows with gestational age, so the same kilogram of gain is worth fewer percentage points later in pregnancy

Worked example

160 cm, 55 kg before pregnancy, 62 kg now, 26+0 weeks, one baby
The category first, because everything else follows from it. BMI = 55 / 1.60² = 55 / 2.56 = 21.5 kg/m². That is from 18.5 to below 25.0, so the standard category is normal weight and the published total for one baby is 11.5 to 16 kg. Note how little room there is: at this height a pre-pregnancy weight of 64 kg gives a BMI of exactly 25.0 and the recommended total drops to 7 to 11.5 kg. Nine kilograms of pre-pregnancy weight separates two ranges that do not overlap.
Now apportion that total to 26+0, which is the step most calculators skip. k = (26 − 13)/27 = 13/27 = 0.4815. Bottom: 0.5 + (11.5 − 0.5) × 0.4815 = 0.5 + 5.296 = 5.80 kg. Top: 2.0 + (16 − 2.0) × 0.4815 = 2.0 + 6.741 = 8.74 kg. So at 26+0 the range is 5.8 to 8.7 kg, not 11.5 to 16 kg. A reader who had gained 7 kg and compared it with 11.5 to 16 would read herself as badly under, and she is not: 7 kg is inside the range for where she is.
The position. Gain = 62 − 55 = 7.0 kg. Position = 100 × (7.0 − 5.796) / (8.741 − 5.796) = 100 × 1.204 / 2.944 = 41% of the way from the bottom of the range to the top — comfortably inside it, nearer the bottom than the top. The midpoint for 26+0 is 7.27 kg, so the gain is 0.27 kg below the midpoint. That is a quarter of a kilogram, which is less than the difference a cup of tea and a coat make to a weighing.
Check the same figure the other way, and watch the source contradict itself. The published weekly rate for a normal-weight singleton is 0.35 to 0.50 kg/week. Run that from 13+0: bottom 0.5 + 0.35 × 13 = 5.05 kg, top 2.0 + 0.50 × 13 = 8.50 kg. Against 5.80 to 8.74 from the pro-rata model, the two models differ by 0.75 kg at the bottom and 0.24 kg at the top, and the 7 kg gain reads as 57% on the rate model against 41% on the pro-rata one. Carry the rate model all the way to 40+0 and it gives 9.95 to 15.5 kg where the published total is 11.5 to 16 kg — 1.55 kg short at the bottom. The published table's rate column and its total column are not arithmetically consistent, and this page shows both rather than picking one and looking confident.
The Asian-Indian cut-off question, at this BMI and at a BMI that matters. At 21.5 kg/m² nothing changes: 21.5 is below 23 and below 25, so both the standard and the Asian-Indian cut-offs put this reader in the same category. Now take 160 cm and 60 kg instead, a BMI of 23.4. On the standard cut-offs that is still normal weight, total 11.5 to 16 kg. On the Asian-Indian threshold of 23 she is over it, and a reader who applied the overweight range would get 7 to 11.5 kg — 4.5 kg lower at both ends, from a change of nothing at all in her body. The page shows both and switches neither, because the 2009 ranges were fitted against the standard boundaries and no published range exists for a category defined at 23.
Twins, and the edges. Same woman carrying twins: the provisional total is 17 to 25 kg, the rate-based rows vanish because no weekly rate was published for twins, and at 26+0 the pro-rata range is 0.5 + 16.5 × 0.4815 = 8.44 to 2.0 + 23 × 0.4815 = 13.07 kg. At 13+0 or earlier, any configuration gives exactly 0.5 to 2.0 kg, the published first-trimester allowance, with no weekly target spread across it. At 40+0, k = 1 and the range is exactly the published total, by construction. Past 40+0 the range stops moving. And a current weight below the pre-pregnancy weight gives a negative gain, which the page prints as negative rather than flooring at zero.
What this page will not tell you. It will not tell you what to eat, how much to gain, whether your gain is a problem, or anything about the baby. It reports where a gain sits in a published population range read at the right point in pregnancy, shows the range as a range, shows the second way of apportioning it, and shows what a different set of BMI cut-offs would do. Everything that makes a number mean something — the scan, the blood pressure, the glucose, the trend across visits, the history — belongs to a midwife or doctor. Pre-pregnancy weight questions in the other direction, and the ideal-body-weight formulas that are often confused with them, are on the ideal body weight page.

The 2009 recommendations as published, and the two places the table does not agree with itself

Two internal inconsistencies, both real and both normally left unmentioned. FIRST, the kilogram and pound columns are each rounded on their own, so converting one into the other does not reproduce the other: the largest gap is 0.20 kg for one baby (28 lb is 12.70 kg where the table says 12.5) and 0.51 kg for twins (54 lb is 24.49 kg where the table says 25). This page computes in kilograms from the kilogram column. SECOND, and larger, the pound and kilogram RATE columns are not conversions of each other at all: 1.0 lb/week is 0.454 kg/week, but the table prints 0.51 kg/week beside it for underweight and 0.42 beside the same 1.0 lb for normal weight — 12% apart in one row and 7% in the other, in opposite directions. The overweight and obesity rows agree to within about 3%. A reader working in pounds and a reader working in kilograms from the same published table are therefore using different numbers, and this page says so rather than silently picking a side.
Pre-pregnancy BMI	Total, one baby (kg)	Total as the CDC prints it (lb)	lb converted to kg	Weekly rate, 2nd and 3rd trimester (kg/week)	Weekly rate as printed (lb/week)
Below 18.5 — underweight	12.5 to 18	28 to 40	12.70 to 18.14	0.51 (0.44 to 0.58)	1.0 (1.0 to 1.3)
18.5 to below 25.0 — normal	11.5 to 16	25 to 35	11.34 to 15.88	0.42 (0.35 to 0.50)	1.0 (0.8 to 1.0)
25.0 to below 30.0 — overweight	7 to 11.5	15 to 25	6.80 to 11.34	0.28 (0.23 to 0.33)	0.6 (0.5 to 0.7)
30.0 and above — obesity	5 to 9	11 to 20	4.99 to 9.07	0.22 (0.17 to 0.27)	0.5 (0.4 to 0.6)
Twins, below 18.5	22.7 to 28.1 — this page’s rounding of the CDC pounds, NOT from the 2009 report	50 to 62	22.68 to 28.12	none published	none published
Twins, 18.5 to below 25.0	17 to 25 (provisional)	37 to 54	16.78 to 24.49	none published	none published
Twins, 25.0 to below 30.0	14 to 23 (provisional)	31 to 50	14.06 to 22.68	none published	none published
Twins, 30.0 and above	11 to 19 (provisional)	25 to 42	11.34 to 19.05	none published	none published

The same gain of 7.0 kg read at four gestational ages, normal-weight singleton

One number, 7.0 kg, read five ways. The last column is what almost every pregnancy weight-gain calculator does: compare the gain so far against the total for term, which makes every reader before about 32 weeks look under-gained and is the single commonest error in this family of pages. The first two columns are what this page does. Note also that the two apportioning models disagree about the same reader by 16 percentage points at 26 weeks and by 47 at 40 weeks — wide enough to move a reader from “below” to “within” at 34+0, where the pro-rata model says −54% and the rate model says −18%. Both come from the same published table. The width of that disagreement is the honest precision of this calculation.
Gestational age	Pro-rata range (kg)	Position	Rate-model range (kg)	Position on the rate model	Range if compared with the 40-week total
13+0	0.5 to 2.0	433% — above	0.5 to 2.0	433% — above	11.5 to 16 — would read as far below
20+0	3.35 to 5.63	160% — above	2.95 to 5.50	159% — above	11.5 to 16 — would read as far below
26+0	5.80 to 8.74	41% — within	5.05 to 8.50	57% — within	11.5 to 16 — would read as far below
34+0	9.06 to 12.89	−54% — below	7.85 to 12.50	−18% — below	11.5 to 16 — would read as below
40+0	11.5 to 16.0	−100% — below	9.95 to 15.50	−53% — below	11.5 to 16 — the same thing at last

What the Asian-Indian BMI cut-offs would change, and what they would not

The rows that move are 23 to 25 and 25 to 27.5-ish, and they move a long way: a BMI of 23.4 goes from a recommended total of 11.5–16 kg to one of 7–11.5 kg, which do not overlap at all. This is why the question cannot be settled quietly. The lower thresholds come from the Indian national consensus on obesity in Asian Indians (Misra and colleagues, 2009, revised 2025), which sets generalised obesity at a BMI above 23; that is a diagnostic statement about cardiometabolic risk and it is well sourced. It is not a statement about gestational weight gain, and the 2009 gestational ranges were fitted against cohorts categorised at 18.5, 25 and 30. So the reader at 23.4 has a real problem with no published answer: the range she is given was derived for women her BMI classes with, and the category she arguably belongs in has no range of its own. The page shows both columns and declines to choose. Note separately that the pair “23 and 27.5” often quoted as the Asian cut-offs is a different set from the Indian consensus pair, comes from an expert consultation whose material this site cannot use, and is not what Indian national guidance says.
Pre-pregnancy BMI	Standard category and total, one baby	Asian-Indian category and the total a reader would apply	Change
17.0	Underweight — 12.5 to 18 kg	Underweight — 12.5 to 18 kg	none: the 18.5 boundary is the same on both
21.5	Normal — 11.5 to 16 kg	Normal — 11.5 to 16 kg	none
23.4	Normal — 11.5 to 16 kg	Over the 23 threshold — 7 to 11.5 kg	4.5 kg lower at both ends
24.8	Normal — 11.5 to 16 kg	Over the 23 threshold — 7 to 11.5 kg	4.5 kg lower at both ends
26.0	Overweight — 7 to 11.5 kg	Over the 25 threshold — 5 to 9 kg	2.0 kg lower at the bottom, 2.5 kg at the top
31.0	Obesity — 5 to 9 kg	Obesity — 5 to 9 kg	none: both are already in the lowest range

Where each figure on this page comes from, and what was rejected

This table exists because the licensing route to each number changed what the page could say. The totals have a clean Government republication and are used freely. The weekly rates do not, and are cited to their own source as figures. The Asian cut-offs most readers have heard of trace to a body whose material this site cannot use at all, so the page uses the Indian national consensus numbers instead and says that they are different numbers. And one thing could not be sourced at any price: a gestational weight-gain range derived against the lower cut-offs. It does not appear to exist, which is why this page shows two categories side by side and settles nothing.
Figure	Source used	What was rejected, or could not be established
Total gain ranges, one baby and twins	The CDC’s weight-gain-during-pregnancy page, which republishes the ranges in pounds and attributes them to the Institute of Medicine. A CDC page is a United States Government work and is usable here. The kilogram figures are the ones printed in the 2009 table itself and are consistent with the CDC pounds to within 0.2 kg for one baby and 0.51 kg for twins.	Reproducing the 2009 report’s own table. The National Academies are a private non-profit and the report is not a Government work, so the route taken is the CDC’s republication of the same numbers. Nothing on this page reproduces report text, prose or criteria.
Weekly rates for the second and third trimesters	The 2009 figures as they appear in National Academy of Medicine material: 0.51 (0.44 to 0.58), 0.42 (0.35 to 0.50), 0.28 (0.23 to 0.33) and 0.22 (0.17 to 0.27) kg/week by rising BMI category. Numbers, cited; no table or text reproduced.	A United States Government republication of the RATE column. The CDC page carries the totals in pounds and NOT the weekly rates, the kilogram equivalents or the first-trimester allowance — so unlike the totals, the rates have no clean Government route and are cited to their own source. This is stated here rather than left to be assumed.
First-trimester allowance 0.5 to 2.0 kg	The footnote the 2009 table attaches to its own rate column, stating that the calculations assume a first-trimester gain of 1.1 to 4.4 lb (0.5 to 2.0 kg). Used as the flat range before 13+0 and as the intercept of both apportioning models.	Any weekly first-trimester rate. None is published, and this page does not manufacture one: the range is held flat to 13+0.
Apportioning from 13+0 over 27 weeks	A derivation performed for this page, not taken from anywhere. Thirteen weeks is the conventional end of the first trimester; 27 weeks is 13+0 to 40+0. The choice is defended numerically: summing the absolute mismatch between the published total and (allowance + rate × weeks) across all four categories gives 3.77 kg at 27 weeks and 5.92 kg at 26, so 27 is the better fit to whatever the source divided by.	Certainty. 14+0 and 26 weeks is equally defensible as a trimester boundary and would raise the implied weekly rate by about 4%; 28 weeks fits the published numbers marginally better still (2.90 kg of total mismatch) but corresponds to no trimester boundary anybody uses. No choice makes the published rate column and the published total column agree exactly, and the page prints both models for that reason.
The BMI category boundaries 18.5, 25.0 and 30.0	Taken from the CDC page that carries the gain ranges, which prints them beside the ranges as “less than 18.5”, “18.5 to 24.9”, “25.0 to 29.9” and “30.0 and above”. Implemented as lower-bound-inclusive: exactly 25.0 is overweight, exactly 30.0 is obesity, exactly 18.5 is normal weight.	The printed “24.9” and “29.9” read literally, which would leave gaps between 24.9 and 25.0. They are rounded displays of “below 25.0” and “below 30.0” and are implemented as such. Also rejected: comparing the raw quotient. The category test is applied to the BMI rounded to one decimal place, because 160 cm and 64.0 kg divide to 24.999999999999996 in binary floating point and a strict test put that in NORMAL WEIGHT — a range 4.5 kg too high at both ends. 95 height-and-weight pairs on a 1 mm by 100 g grid disagree between the raw and the rounded test at the 25 boundary. The cost is an effective boundary at 24.95, which is stated on the page.
Asian-Indian cut-offs of 23 and 25	The Indian national consensus on the diagnosis of obesity in Asian Indians (Misra and colleagues, J Assoc Physicians India 2009; revised definition, Diabetes Metab Syndr 2025), which sets overweight at a BMI of 23 to 24.9 and obesity at 25 and above, and in its 2025 revision makes 23 the generalised-obesity threshold. Cited by figure.	The widely quoted Asian pair “23 and 27.5”. Those are the additional trigger points proposed by a 2004 expert consultation whose publications are licensed on terms this commercial, advertising-carrying site cannot meet — and which copyright does not launder by going through a third party that has reprinted them. They are also not the numbers Indian national guidance uses, so quoting them to an Indian readership would be doubly wrong. Also rejected: any gestational weight-gain range defined against these cut-offs. The author of this page looked and found none published by any body; cohort studies in Asian populations propose lower optimal ranges (for example 12 to 14 kg for normal-weight Chinese women against the 2009 report’s 11.5 to 16) but those are study proposals on Chinese-specific categories, not adopted recommendations, and none is specific to Indian women.
What Indian women actually gain	The REVAMP cohort in Pune (Dangat and colleagues, Front Med 2022; 640 urban women): median gain at 40 weeks of 13.18 kg in underweight women, 11.74 kg in normal-weight women and 10.48 kg in overweight or obese women, on the standard BMI cut-offs. An observation, not a recommendation, and used on this page only to say that the observed median for a normal-weight Indian woman sits just above the BOTTOM of the 11.5 to 16 kg range rather than in the middle of it.	Treating that median as a target. It is a description of one urban, mostly higher-socioeconomic cohort.
The twin underweight figure	The CDC page, which prints 50 to 62 lb for underweight women with twins and footnotes it to Luke and colleagues (2003) rather than to the 2009 report.	Attributing it to the 2009 report, which makes no recommendation for this cell and says so. The page flags it in place.
Obstetric guidance generally	Not used as a source of text or criteria anywhere on this page.	Reproducing guidance from the obstetric colleges. Their guidance is copyrighted; a committee opinion can be cited by number and figure, which this page has no need to do, since the figures it needs come from the CDC. Guidance from the UK national institute is not used anywhere on this site: its open content licence is United Kingdom-only and forbids displaying the licensed information next to advertising, and this site carries advertising.

Why this page apportions the range to your gestational age, and why it shows you two sets of BMI cut-offs instead of choosing one

The commonest mistake in this family of calculators is comparing a gain so far against a total for term. The published recommendation for a normal-weight singleton pregnancy is 11.5 to 16 kg, and that figure is for the whole of it — forty weeks. A reader at 26 weeks who has gained 7 kg and sees “11.5 to 16 kg” on the screen concludes she is 4.5 kg behind, and she is not behind at all: apportioned to 26+0, the range is 5.8 to 8.7 kg and 7 kg sits comfortably inside it, a little below the middle. Every reader before roughly 32 weeks is mis-read by the whole-pregnancy comparison, and the earlier in pregnancy she looks the worse the error is. So this page apportions: it holds the range flat at the published first-trimester allowance of 0.5 to 2.0 kg until 13+0, then grows it linearly across the 27 weeks to 40+0, where it lands exactly on the published total. The whole-pregnancy figures are still on the page, in their own rows, labelled as totals for term.

The published table contains two statements that do not reconcile, and this page prints both. The 2009 recommendations give, for each BMI category, a total gain for term AND a rate of gain per week for the second and third trimesters, plus a footnote saying the calculations assume 0.5 to 2.0 kg in the first trimester. Those three things should fit together and they do not. Take the normal-weight row: run the published rate of 0.35 to 0.50 kg/week from 13+0 to 40+0 and add the published allowance, and you get 9.95 to 15.5 kg, where the published total is 11.5 to 16. The bottom end is 1.55 kg short. The underweight and obesity rows reconcile to within 0.35 kg; the normal-weight bottom end is the bad one. Pick a different number of weeks and the mismatch moves but never disappears: summed across all four categories it is 5.92 kg at 26 weeks, 3.77 kg at 27, and 2.90 kg at 28, and 28 weeks is not a trimester boundary. The page therefore offers two models. The pro-rata model stretches the published total across the apportioning period, so it is right at 40+0 by construction. The rate model runs the published weekly rate forward, so it is faithful to the rate column and wrong at term. The gap between them is printed, and it is the honest precision of this calculation: at 34+0 the same 7 kg gain reads as 54% below the range on one model and 18% below on the other.

The pound and kilogram columns of the same published table are not conversions of each other. This sounds pedantic and is not. For the totals the discrepancy is small — 28 lb is 12.70 kg where the table prints 12.5, the worst case being about 0.2 kg for a singleton and 0.51 kg for twins, which is rounding and harmless. For the weekly RATES it is not rounding. The table prints 1.0 lb/week for the underweight category and 0.51 kg/week beside it; 1.0 lb is 0.454 kg, so those two cells are 12% apart. For normal weight it prints 1.0 lb/week and 0.42 kg/week, which are 7% apart in the other direction. The overweight and obesity rows agree to within about 3%. A reader working in pounds and a reader working in kilograms from the same table are therefore using materially different weekly rates, and the pound figures look like the heavily rounded ones. This page computes in kilograms from the kilogram column, and says so here rather than leaving the reader to discover it.

The Asian-Indian BMI cut-off question, which this page refuses to settle quietly. The ranges above are indexed on BMI categories whose boundaries are 18.5, 25 and 30. There is a long-standing and well-evidenced argument that those boundaries sit too high for South Asian bodies: at the same BMI, Asian Indians carry more body fat and more visceral fat, and insulin resistance, dysglycaemia and cardiometabolic risk arrive at a lower BMI. The Indian national consensus on obesity, published in 2009 and revised in 2025, acts on exactly that and puts the generalised-obesity threshold at a BMI of 23 rather than 25. If you apply those lower boundaries to the gestational ranges, a woman with a BMI of 23.4 stops being normal weight — and the range a reader would then apply is 7 to 11.5 kg instead of 11.5 to 16 kg. Two ranges that do not overlap, for a woman whose body has not changed. Here is why this page will not make that substitution for you. The consensus statement is about diagnosing obesity, not about how much weight to gain in pregnancy. The 2009 gestational ranges were fitted on cohorts categorised at 18.5, 25 and 30, so moving a reader across the boundary hands her a range that was never derived for women like her — a different error, not a smaller one. And nobody has published gestational ranges derived against the lower cut-offs: the author of this page went looking and found none from any body, only cohort studies in Asian populations proposing lower optimal ranges on their own national categories, which are study findings rather than recommendations and none of which is specific to Indian women. So the page shows both categories and both ranges, flags it loudly when they differ, and says the question is open. One further point worth being exact about: the Asian cut-offs most often quoted as “23 and 27.5” are not the Indian consensus pair at all. They come from a 2004 expert consultation whose publications are licensed on non-commercial terms that this advertising-funded site cannot meet, and which going through a third party that has reprinted them would not fix. This page uses the Indian national numbers, 23 and 25, and names the difference.

What a published range is, and what being outside one does and does not mean. It is a population statement: across large cohorts, gains inside these bands were associated with fewer adverse outcomes for mother and baby than gains outside them. It is not a measurement of you and it is not a threshold at which anything happens. The bands are several kilograms wide and individual variation is wider still; the observed median gain in a Pune cohort of 640 urban women was 11.74 kg for normal-weight mothers, which is just above the BOTTOM of the 11.5 to 16 kg range rather than near its middle. A single weighing carries roughly a kilogram of noise from clothing, time of day and hydration, and a recalled pre-pregnancy weight carries more. A booking weight used in place of a pre-pregnancy weight distorts the answer twice over, raising the BMI and shrinking the apparent gain. So read the position above as an orientation, read the trend across several visits rather than one reading, and take anything that concerns you to a midwife or doctor, who has the scan, the blood pressure, the glucose and the history that this page does not have and cannot have. There are no judgement words anywhere on this page, by design, and none of its three bands means well done or badly done.

What this page deliberately does not do. It does not compute a gestational age: that is the due date page’s job, and correction for prematurity after the birth belongs to the corrected age page in the medical set. It gives no energy or protein target: those are the energy requirement page and the protein requirement page, and neither of them makes a recommendation either. It says nothing about the baby’s growth, nothing about gestational diabetes, and nothing about blood pressure. It does not plot a centile chart, because the reference data for that is held by bodies whose licences this site cannot use. And it says nothing about ideal body weight, which is a different quantity entirely and lives on the ideal body weight page — a page about drug dosing, not about pregnancy.

Frequently asked questions

Why is the range on this page so much smaller than the 11.5 to 16 kg I have read everywhere?

Because 11.5 to 16 kg is the total for a whole term pregnancy and the page is showing you the range apportioned to the gestational age you entered. At 26+0 the apportioned range for a normal-weight singleton is 5.8 to 8.7 kg; at 40+0 it is exactly 11.5 to 16 kg, because the pro-rata model is anchored to land there. Both figures are on the page: the apportioned range in the rows labelled “for this gestational age” and the term total in the rows labelled “recommended TOTAL for term”. Comparing a gain at 26 weeks with a total for 40 weeks is the single commonest error in pregnancy weight-gain calculators and it makes almost everybody look under-gained.

Should I use the Asian or Indian BMI cut-offs instead of the standard ones?

This page cannot answer that for you and will not pretend to. What it does is show both. The Indian national consensus on obesity puts the generalised-obesity threshold at a BMI of 23 rather than 25, and that position is well evidenced for what it is about — diagnosing obesity and cardiometabolic risk in Asian Indians. The difficulty is that the gestational weight-gain ranges were derived on cohorts categorised at 18.5, 25 and 30, and no body has published gain ranges derived against the lower boundaries. So applying the lower cut-off to the existing ranges gives a woman with a BMI of 23.4 a recommended total of 7 to 11.5 kg instead of 11.5 to 16 kg, from a range that was fitted to a different group of women. That is a different error, not a correction. The honest answer is that the question is open, the two answers are both on the page, and which to use is a conversation with a midwife or doctor who knows the rest of your picture. Note too that the “23 and 27.5” pair often quoted as the Asian cut-offs is a different set from the Indian consensus pair of 23 and 25, comes from a source this site cannot use, and is not what Indian national guidance says.

Why does the page give two different ranges for the same gestational age?

Because the published source gives two things that do not agree, and hiding one of them would be worse than showing both. The 2009 recommendations state a total for term and a weekly rate for the second and third trimesters, plus an assumed first-trimester gain of 0.5 to 2.0 kg. Run the weekly rate from 13+0 to 40+0 on top of that allowance and, for a normal-weight singleton, you arrive at 9.95 to 15.5 kg where the published total is 11.5 to 16 — 1.55 kg short at the bottom. There is no number of weeks that makes all four categories reconcile. The headline position uses the pro-rata model, which stretches the published total so that it is exactly right at 40+0; the rows labelled “by the PUBLISHED WEEKLY RATE” use the other. The gap between them is printed because it is the real width of the uncertainty, and at 34 weeks it is wide enough to change which side of the range a reader falls on.

Is a BMI of exactly 25.0 normal weight or overweight?

Overweight. The boundaries are lower-bound-inclusive: below 18.5 is underweight, 18.5 up to but not including 25.0 is normal weight, 25.0 up to but not including 30.0 is overweight, and 30.0 and above is obesity. The published table writes the middle bands as “18.5 to 24.9” and “25.0 to 29.9”, which looks as though it leaves a gap between 24.9 and 25.0; it does not — those are rounded displays of “below 25.0” and “below 30.0”. One implementation detail matters enough to state. The test is applied to the BMI ROUNDED TO ONE DECIMAL PLACE, which is the figure the page prints, so what you can see is what chose the category. The reason is not cosmetic: at 160 cm and 64.0 kg the raw division gives 24.999999999999996, because 1.6 cannot be represented exactly in binary, and a strict comparison would put a BMI of exactly 25.0 into the normal-weight category and hand the reader a range 4.5 kg too high at both ends. Over ordinary adult heights and weights on a 1 mm by 100 g grid, 95 height-and-weight pairs disagree between the raw and the rounded test at the 25 boundary alone. Rounding first removes that silently-wrong case, at the cost of an effective boundary at 24.95 rather than 25.0 — which is four hundredths of a BMI unit, far inside the error on a measured height. Either way the categories are steps and nothing about a body changes at 25.0, while the recommended total drops by 4.5 kg at both ends, so the page flags any BMI within 0.5 of a boundary and tells you to read both neighbouring ranges.

What if I have gained nothing, or lost weight?

The page reports it as it is: the gain goes negative and the position goes below the range, with no judgement word attached. In the first trimester this is ordinary — nausea and vomiting commonly produce no gain or a small loss, which is why the published ranges allow as little as 0.5 kg for the whole of the first thirteen weeks and attach no weekly rate to them at all. Later in pregnancy a loss is something to mention to a midwife or doctor rather than to interpret from a calculator. Check the obvious arithmetic cause first: the two weight fields entered the wrong way round. And check which weight you used as the pre-pregnancy figure — a booking weight taken at 10 weeks already contains part of the gain being measured.

How reliable are the twin ranges?

Less reliable than the singleton ones, and the source says so: it publishes them as provisional guidance rather than as recommendations, because the evidence behind them is much thinner. Three practical consequences. There is no published weekly rate for twins at all, so the rate-based comparison rows disappear and the pro-rata apportioning has nothing to be checked against. The ranges are stated only to the nearest whole or half kilogram, so a percentage position inside them carries more precision than the evidence does. And there is no 2009 recommendation for an underweight twin pregnancy — the figure this page uses for that cell, 50 to 62 lb, is the one the CDC prints in its place from a different 2003 source, and the page labels it when you land on it. Triplets and above have no published range anywhere and this page refuses to extrapolate one.

Why does the page ask for gestational age instead of working it out from my dates?

Because another page already does that and two pages doing the same date arithmetic is two pages that can disagree. The due date and gestational age page derives weeks and days from a last menstrual period or a scan measurement and explains which dating method it is using; this page takes the result. Enter it as completed weeks plus days, the obstetric weeks+days notation: 26 in the first field and 3 in the second means 26 completed weeks and 3 days, which is the twenty-seventh week. That distinction is where off-by-one errors live. The page converts to decimal weeks by adding days divided by seven, so a day of gestational age is worth about 175 g at the normal-weight pro-rata rate — less than the noise on a single weighing.

Does being outside the range mean something is wrong?

No. The range is a population statement: across large cohorts, gains inside these bands were associated with fewer adverse outcomes than gains outside them. It is not a measurement of you, it is not a threshold at which anything happens, and the bands are several kilograms wide with individual variation wider still. The observed median gain among normal-weight women in a Pune cohort of 640 was 11.74 kg, which sits just above the bottom of the 11.5 to 16 kg band rather than in the middle of it — so a population can be perfectly healthy and cluster near one end of a recommended range. What is worth attention is a trend across several visits, not a single reading, and the person to take it to is a midwife or doctor, who has the scan, the blood pressure, the glucose and the history. There are no judgement words on this page and none of its bands means well done or badly done.

Why is there no centile chart of weight gain?

Because the reference data that would be needed to draw one, as parameters varying continuously with gestational age, comes from bodies whose licences this site cannot use, and because this engine has no table-lookup function. Rather than approximate a centile chart badly or extrapolate a formula into a shape it was not fitted for, the page sticks to what the published recommendation actually says: a range of totals by pre-pregnancy BMI category, a weekly rate for part of the pregnancy, and an allowance for the first trimester. Everything on this page is one of those three numbers, an arithmetic consequence of them, or a statement about where they disagree.

Related calculators

References

Centers for Disease Control and Prevention, Weight Gain During Pregnancy (Maternal Infant Health), last reviewed 13 December 2023. The source used on this page for the total gain ranges and for the BMI category boundaries, both for one baby (28–40, 25–35, 15–25 and 11–20 lb by rising BMI category) and for twins (50–62, 37–54, 31–50 and 25–42 lb). The page attributes the recommendations to the Institute of Medicine, with one stated exception: the underweight-twins figure, which it footnotes to Luke B, Hediger ML, Nugent C et al. (2003) rather than to the 2009 report. A CDC page is a United States Government work and is usable on a commercial site; this is the route by which the 2009 ranges reach this page, because the report itself is the work of a private non-profit. VERIFIED on the CDC page: it carries the totals in pounds and does NOT carry the weekly rates, the kilogram equivalents or the first-trimester allowance.
Institute of Medicine and National Research Council, Weight Gain During Pregnancy: Reexamining the Guidelines (2009). Cited for the figures this page could not obtain from a Government source: the kilogram totals (12.5–18, 11.5–16, 7–11.5 and 5–9 kg; twins 17–25, 14–23 and 11–19 kg, published as provisional), the weekly rates for the second and third trimesters (0.51 [0.44–0.58], 0.42 [0.35–0.50], 0.28 [0.23–0.33] and 0.22 [0.17–0.27] kg/week), and the footnote stating that the calculations assume a first-trimester gain of 1.1–4.4 lb (0.5–2.0 kg). Cited as figures. No table, prose or criteria from the report is reproduced here. Figures confirmed against the table as reproduced in National Academy of Medicine discussion material on gestational weight gain among women with obesity.
Misra A, Chowbey P, Makkar BM et al. Consensus statement for diagnosis of obesity, abdominal obesity and the metabolic syndrome for Asian Indians. J Assoc Physicians India 2009;57:163–70 — overweight at a BMI of 23.0–24.9 and obesity at 25.0 and above for Asian Indians. Updated by Misra A, Vikram NK, Ghosh A et al. Revised definition of obesity in Asian Indians living in India. Diabetes Metab Syndr 2025;19:102989, which makes 23 the generalised-obesity threshold and adds a staged definition using abdominal obesity and comorbidity. Cited by figure for the alternative cut-offs this page displays alongside the standard ones. PROVENANCE NOTE: these are diagnostic thresholds for obesity, not gestational weight-gain categories, and neither statement proposes gestational ranges.
LICENSING POSITION, recorded because it determined the sources above. The Asian BMI cut-offs most often quoted, 23 and 27.5, are the additional trigger points proposed by a 2004 expert consultation convened by an international health body whose publications are licensed on NonCommercial terms requiring permission for commercial use. This site carries advertising and is therefore commercial, so that material is not used here at all — not directly and not through a third party that has reprinted it, because copyright does not launder. The page uses the Indian national consensus pair instead, 23 and 25, and states that they are different numbers from the pair readers may have seen. Separately, no guidance from the UK national institute is used anywhere on this site: its open content licence is United Kingdom-only and forbids display of the licensed information next to advertising.
Dangat K, Khaire A, Joshi A et al. Gestational weight gain in the REVAMP pregnancy cohort in Western India: comparison with international and national references. Front Med 2022;9:1022990. 640 urban pregnant women in Pune; median gain at 40 weeks 13.18 kg (underweight), 11.74 kg (normal weight) and 10.48 kg (overweight or obese), on the standard BMI cut-offs rather than Asian-specific ones. Cited on this page for one point only: the observed median for a normal-weight Indian woman in this cohort sits just above the BOTTOM of the 11.5–16 kg recommended range rather than near its middle, which is useful context for a reader who reads the midpoint as a target. An observation in one urban, largely higher-socioeconomic cohort, not a recommendation.
Sun Y, Shen Z, Zhan Y et al. Investigation of optimal gestational weight gain based on the occurrence of adverse pregnancy outcomes for Chinese women: a prospective cohort study. Reprod Biol Endocrinol 2021. Cited as evidence that cohort work in Asian populations arrives at materially lower optimal ranges than the 2009 recommendations — at least 8 and under 12 kg if underweight, at least 12 and under 14 kg at normal weight, at least 8 and under 10 kg if overweight, and under 8 kg with obesity. These are study proposals on Chinese-specific BMI categories, not adopted recommendations, and none of them is specific to Indian women. Used here only to support the statement on the page that the question of Asian-specific ranges is live and unsettled, not as a source of any figure this page computes with.
WHAT COULD NOT BE ESTABLISHED, stated rather than glossed over. (1) No gestational weight-gain range derived against the Asian-Indian BMI cut-offs of 23 and 25 could be found, published by any body. If one exists, this page does not know of it, and that absence is the whole reason the page shows two categories side by side instead of switching between them. (2) No United States Government republication of the 2009 WEEKLY RATE column could be found; the CDC page carries only the totals, in pounds. (3) The number of weeks the 2009 calculations divided by is not stated in the material available here and has been inferred numerically, with the inference and its alternatives set out in the provenance table.
Derivations performed for this page rather than taken from a source, recorded so they can be checked. (1) Apportioning from 13+0 to 40+0 is 27 weeks; the pro-rata range is L(t) = 0.5 + (T_lo − 0.5)(t − 13)/27 and U(t) = 2.0 + (T_hi − 2.0)(t − 13)/27, which equals the published total exactly at t = 40 and the published first-trimester allowance exactly at t = 13. (2) The published weekly rate does NOT reconcile with the published total: 0.5 + 0.35 × 27 = 9.95 and 2.0 + 0.50 × 27 = 15.5 against a published 11.5–16 for normal weight, a shortfall of 1.55 kg at the bottom. Summed absolute mismatch across all four singleton categories is 3.77 kg at 27 weeks, 5.92 kg at 26 and 2.90 kg at 28. (3) The weekly rate the pro-rata model implies is (T_lo − 0.5)/27 to (T_hi − 2.0)/27, which for normal weight is 0.407 to 0.519 kg/week against a published 0.35 to 0.50. (4) Converting the published pounds to kilograms at 0.45359237 kg/lb differs from the published kilogram column by up to 0.20 kg for a singleton and 0.51 kg for twins; converting the published pound RATES differs from the published kilogram rates by 12% (underweight) and 7% (normal weight) and by under 3% in the other two categories. (5) At 160 cm, 1 cm of height error moves the BMI by about 0.27 kg/m², and 9 kg of pre-pregnancy weight separates a BMI of 21.5 from a BMI of exactly 25.0.
A note on what a BMI category is doing in this calculation at all. BMI is a ratio of mass to the square of height and is not a measurement of body composition; at the same BMI, body fat and visceral fat differ systematically between populations, between individuals and across a lifespan, which is precisely the argument behind the Asian-specific cut-offs. The 2009 recommendations use BMI categories because that is what the cohorts they were fitted on recorded, not because BMI is the right variable. Nothing on this page should be read as a claim that a BMI category describes a person. It selects which published range the page quotes, and that is the whole of its role here.

CalcEngines health calculators are for education and for checking arithmetic that has already been decided elsewhere. They are not medical advice, they do not decide what to give, and they do not replace the judgement of a doctor, nurse, midwife or dietitian who knows the person in front of them. Every figure depends on the values you enter and on the assumptions stated on the page — check it against the prescription, the product label and your local policy before acting on it.