Fluid Balance Chart Calculator

Totals a fluid balance chart over a shift or 24 hours: oral, intravenous, feed and flushes in; urine, drains, vomit and stool out; an insensible loss you can set; and a net balance whose sign is stated in words as well as in a minus sign. It carries a previous figure forward for the cumulative balance, and it converts the urine row into mL/kg/h against the oliguria thresholds. It adds up a chart that has already been written. It does not prescribe fluid.

Last updated 1 Oct 2026

This calculates a rate or a volume from a prescription that has already been written. It does not decide what to give. Check every figure against the prescription and your local policy, and have it independently checked before administration.

Totals, net balance, cumulative balance and urine output in mL/kg/h

chart rows → totals, signed net balance and mL/kg/h

Oral and sips (mL)Everything the patient drank, including sips with medicines and the water in jellies and soups if your chart records them. This is the row most often under-recorded, and under-recording intake makes a chart look more negative than the patient is.

Intravenous fluids and infusions (mL)Crystalloid, colloid, blood and blood products, and the carrier volume of any continuous infusion. Take the volumes actually delivered from the pump histories rather than the volumes prescribed; a bag that ran slow or was paused is the commonest reason a chart and a patient disagree.

Enteral feed and water via tube (mL)Nasogastric, nasojejunal or gastrostomy feed plus any water given down the tube, including the water used to flush before and after feeds if it is not counted in the flush row below. Count it once, not twice.

Flushes, medicine volumes and line fluids (mL)Saline flushes, the diluent volume of intravenous medicines, line maintenance fluid and arterial line flush. Individually trivial, collectively not: eight 10 mL flushes and four 100 mL antibiotic infusions is 480 mL a day, which is a third of a litre more than most charts admit to.

Urine (mL)Measured from a catheter bag or from measured voids. This row does double duty: it is part of the output total and it is the numerator of the mL/kg/h figure below, so an estimated or missed void affects both.

Drains, stoma and gastric aspirate (mL)Surgical drains, chest drains, stoma output, nasogastric aspirate and any other measured collection. Measured volumes only.

Vomit (mL)Estimated rather than measured in almost every case, and generally underestimated. Record what was estimated rather than leaving it at zero: an estimate that is written down can be revised, and a blank cannot.

Loose stool (mL)Only worth recording when it is a real fluid loss — diarrhoea, high-output stoma, a bowel preparation. Formed stool carries of the order of 100 to 200 mL of water a day and is conventionally left inside the insensible allowance rather than counted here.

Estimated insensible losses (mL per 24 hours)An ESTIMATE, not a measurement, and the only figure on this page that is not read off a chart. Entered per 24 hours and scaled to the period below. About 400 mL a day leaves through the skin and about 400 mL through the respiratory tract in an unstressed adult, so 800 mL per 24 hours is the usual starting figure and 500 to 1,000 mL covers most ward patients; 50 mL an hour, or 1,200 mL a day, has been suggested for hospitalised patients generally. Raise it for fever, for tachypnoea, for an open abdomen, for burns and for a hot environment. Lower the respiratory part towards nothing when the patient is breathing humidified gas or is ventilated with a heat and moisture exchanger. The rows below show what the net balance would be at 500 and at 1,000 mL per 24 hours so you can see how much of the answer this one field owns.

Period the chart covers (hours)The span of chart you are totalling: 24 for a full day, 12 or 8 for a shift. Everything on the page is scaled to it, including the insensible allowance, which is why that field is entered per 24 hours rather than per period. Getting this wrong is a factor-of-two or factor-of-three error on the insensible row and on every rate.

Body weight (kg)Used only for the urine output in mL/kg/h. Use a measured weight if there is one. In a patient who has gained several litres of fluid, the admission weight is the better denominator for a urine output than today’s weight, because today’s weight includes the fluid you are trying to assess.

Cumulative balance carried forward (mL, 0 if none)The running cumulative balance at the end of the last period, with its sign: negative if the patient was in deficit. Leave it at 0 and the cumulative row disappears rather than printing a figure that is only this period repeated. The cumulative balance is the number that matters clinically and the one most often missing from a chart.

-190mLExample

Oral 600 mL, intravenous 1,000 mL and flushes 60 mL in; urine 900 mL and drains 150 mL out; insensible loss taken as 800 mL per 24 hours; a 70 kg patient over 24 hours with nothing carried forward

Four sums and a subtraction, with the one estimated term kept visible

in = oral + IV + feed + flushes · out_measured = urine + drains + vomit + stool · insensible over the period = (mL per 24 h) × hours / 24 · net = in − out_measured − insensible · cumulative = carried forward + net · urine output (mL/kg/h) = urine / weight / hours

net: positive means more went in than came out, negative means more came out than went in. The sign is the finding and it is the thing a hand-totalled chart loses
insensible: the only estimated term on the page. Entered per 24 hours and scaled to the period, so a 12-hour chart gets half of it. About 400 mL a day through the skin and 400 mL through the respiratory tract in an unstressed adult
cumulative: the running total across periods. Shown only when a figure is carried forward, because a cumulative balance that equals this period’s balance is not a cumulative balance
urine output: mL per kilogram per hour. The weight and the hours are both divisors, so an error in either moves it proportionally: the same 900 mL is 0.54 mL/kg/h in a 70 kg patient over 24 hours and 1.07 over 12 hours
the oliguria thresholds: below 0.5 mL/kg/h is the conventional definition of oliguria. KDIGO’s urine criteria are below 0.5 mL/kg/h for 6 to 12 hours (stage 1), below 0.5 for 12 hours or more (stage 2), and below 0.3 for 24 hours or more or anuria for 12 hours or more (stage 3). Every one of them has a duration in it, which a single period’s total cannot establish

Worked example

Oral 600 mL, intravenous 1,000 mL and flushes 60 mL in; urine 900 mL and drains 150 mL out; insensible loss taken as 800 mL per 24 hours; a 70 kg patient over 24 hours with nothing carried forward
Intake: 600 + 1,000 + 0 + 60 = 1,660 mL. The 60 mL of flushes is the row people leave out, and leaving it out would have made the balance 60 mL more negative.
Measured output: 900 + 150 + 0 + 0 = 1,050 mL. Subtract that from the intake and the chart reads plus 610 mL — a positive balance, and the figure a ward chart would carry forward.
Insensible loss over 24 hours at 800 mL a day is 800 mL, so total output is 1,050 + 800 = 1,850 mL and the net balance is 1,660 − 1,850 = minus 190 mL. The sign has flipped. The measured rows say the patient gained 610 mL and the complete calculation says they lost 190 mL, and the difference is one number that nobody measured.
So how well is that known? At 500 mL per 24 hours the balance is plus 110 mL. At 1,000 mL per 24 hours it is minus 390 mL. The plausible range for an unstressed adult therefore spans 500 mL and straddles zero: this chart does not establish the sign of the balance at all. The insensible loss at which it balances exactly is 610 mL per 24 hours, which sits squarely inside the plausible range.
That is why the page prints the balance rounded to the nearest 50 mL as well. Minus 190 mL implies the net is known to about 1 per cent of the day's intake, and it is not. Minus 200 mL is the honest way to say it, and quoting an insensible loss to three significant figures would be worse still.
The urine row, separately: 900 mL / 70 kg / 24 h = 0.54 mL/kg/h, above the 0.5 mL/kg/h oliguria threshold. Change the period to 12 hours and the same 900 mL becomes 1.07 mL/kg/h, because the hours are a divisor — which is the reason this page asks for the period explicitly rather than assuming a day. Use the companion urine output calculator for the interpretation of that figure in its own right; this page's job is to total the chart it sits in.
And the arithmetic nobody does: carry forward. If yesterday closed at minus 1,400 mL, the cumulative balance is now minus 1,590 mL. Four consecutive days like this one and the patient is a litre and a half down while every individual day's chart looks unremarkable. In a 2016 audit at a UK major trauma centre only 12 per cent of fluid charts had a running 24-hour total recorded at all, which is the defect this page is for.

Where the insensible loss comes from, and what moves it

**Every figure in the middle column is an estimate and the page lets you override the total.** The reason to show the breakdown is that it tells you which way to move it: a febrile tachypnoeic patient on dry oxygen is at the top of the range or above it, and a ventilated patient on humidified gas with a normal temperature is below it. A page that printed an insensible loss as 812 mL would be claiming a precision that nothing in this table supports.
Route	Unstressed adult, per 24 h	What changes it
Skin, transepidermal, not sweat	about 400 mL	rises with fever, a hot or dry environment, burns and an open abdomen. About 10 per cent is conventionally added to this component per degree above 38 °C
Respiratory tract	about 400 mL	rises with minute ventilation, so 20 to 50 per cent more with marked tachypnoea. Falls towards nothing on fully humidified gas, which is why a ventilated patient on a heat and moisture exchanger loses little this way
Total insensible	about 800 mL	a working range of 500 to 1,000 mL covers most ward patients; 50 mL an hour, or 1,200 mL a day, has been suggested for hospitalised patients generally
Sweat, when present	not in the figure above	can be litres. Visible sweating is a measured-output problem that nobody measures, and it is the single largest source of error in a hot, septic patient
Water in formed stool	about 100 to 200 mL	conventionally left inside the insensible allowance. Diarrhoea and a high-output stoma are not, and go in the output rows
Metabolic water production	about 300 mL gained, not lost	generated by oxidation of substrate. Most bedside conventions fold it into the 800 mL figure rather than carrying it separately, which is one reason the figure is a convention and not a measurement

The urine thresholds, and the duration that belongs to each

**Every KDIGO urine criterion has a duration in it, and a single period’s total cannot establish a duration.** This page converts the urine row of one chart into mL/kg/h and tells you which side of 0.5 and 0.3 it falls; it cannot tell you for how long, and it does not stage anything. KDIGO also has creatinine criteria that this page knows nothing about, and a patient can be staged on those with a perfectly good urine output. For the urine figure interpreted on its own, use the urine output calculator.
Figure	Threshold	Duration in the criterion	What it is
Oliguria, conventional	below 0.5 mL/kg/h	none stated	the usual bedside definition, and a prompt to look rather than a diagnosis
KDIGO stage 1, urine criterion	below 0.5 mL/kg/h	6 to 12 hours	acute kidney injury stage 1 on urine output alone
KDIGO stage 2, urine criterion	below 0.5 mL/kg/h	12 hours or more	stage 2 on urine output alone
KDIGO stage 3, urine criterion	below 0.3 mL/kg/h	24 hours or more	stage 3 on urine output alone
KDIGO stage 3, anuria	effectively no urine	12 hours or more	stage 3 on urine output alone
Commonly quoted adequate output	0.5 mL/kg/h or above	none stated	above the oliguria threshold for the period measured, which is not the same as adequate renal perfusion

Why a hand-totalled chart goes wrong, and which of these numbers is actually a measurement

A fluid balance chart is the only continuous record of what went into a patient and what came out, and it is added up by hand at the end of a shift by whoever has least time. The arithmetic is trivial and the failure modes are not. An audit at a UK major trauma centre in 2016 found that only 12 per cent of patients with fluid charts had a running 24-hour total recorded at all, and that a quality-improvement push raised it to 72 per cent before it fell back to 32. The number that matters most is the one most often missing, and the reason is structural rather than careless: the running total is an extra task, it has to be done at a fixed time, and nothing stops working when it is skipped.

The sign is what gets lost. Two columns of four-figure numbers subtracted under pressure produce a magnitude reliably and a direction less reliably, and a balance of minus 800 mL and plus 800 mL are opposite findings. This page prints the sign as a minus sign, as a coloured chip and as a sentence, because the one thing a totalling tool should never let you misread is which way round the answer is.

One of these numbers is not a measurement, and the page is built around saying so. Oral, intravenous, feed, flushes, urine, drains, vomit and stool are things somebody wrote down. Insensible loss is an estimate: roughly 400 mL a day through the skin and 400 mL through the respiratory tract in an unstressed adult, so about 800 mL in total, with 500 to 1,000 mL covering most ward patients and a suggested 50 mL an hour for hospitalised patients generally. It rises with fever, with tachypnoea, with heat, with burns and with an open abdomen, and it falls towards the skin component alone in a patient breathing fully humidified gas. That range is half a litre wide, which is larger than most of the balances anybody worries about. So the page gives you the balance at 500 and at 1,000 mL per 24 hours, tells you the insensible loss at which the chart would balance exactly, prints the net rounded to the nearest 50 mL, and sweeps the estimate across its whole plausible range in the chart. When the sign of the balance depends on the estimate, it says so in the result note. An insensible loss printed to three significant figures is a lie about how well it is known, and a net balance built on one inherits the lie.

Flushes are the other systematic error, and they only go one way. Saline flushes, the diluent volumes of intravenous antibiotics, line maintenance fluid and arterial line flush are each too small to seem worth recording. Eight 10 mL flushes and four 100 mL antibiotic infusions is 480 mL in a day. They are always intake, never output, so omitting them biases every chart negative by a few hundred millilitres — in the same direction as an over-generous insensible estimate, and in a patient who is being assessed for exactly that.

What this page is not. It totals a chart and converts the urine row into mL/kg/h against the published thresholds. It does not prescribe fluid, it does not recommend a volume or a rate, it does not stage acute kidney injury, and it does not know whether the balance it has calculated is the one the patient needs — a negative balance is the goal in decompensated heart failure and a danger in sepsis, and nothing on a chart distinguishes them. For the urine figure interpreted in its own right, including the staging criteria and the weight questions that go with it, the medical vertical’s urine output calculator is the page for that and this one deliberately stops at the arithmetic.

Frequently asked questions

Should insensible losses be in the chart at all?

Most ward charts do not include them, which is why this page prints both figures: the net balance from the measured rows only, which is what the chart will say, and the net balance including an insensible allowance, which is what the patient is actually doing. Neither is wrong; they answer different questions. The reason to include an allowance is that for a typical adult it is of the order of 800 mL a day, which is larger than most of the balances anybody acts on, so a chart that omits it reads systematically positive. The reason to be careful is that it is an estimate, and this page shows how much of the answer it owns rather than burying it in a total.

What figure should I use for insensible loss?

Start at 800 mL per 24 hours for an unstressed adult — roughly 400 mL through the skin and 400 mL through the respiratory tract — and treat 500 to 1,000 mL as the range that covers most ward patients. Move it up for fever, tachypnoea, a hot or dry environment, burns or an open abdomen; about 10 per cent is conventionally added to the skin component per degree above 38 °C and 20 to 50 per cent to the respiratory component for marked tachypnoea. Move it down towards the skin component alone when the patient is breathing fully humidified gas, which is why a ventilated patient on a heat and moisture exchanger loses little by that route. Visible sweating is not in any of these figures and can be litres. Whatever you use, record the figure you used: a balance quoted without its insensible assumption cannot be checked by the next person.

Why does the page hide the cumulative balance when I leave the carried-forward figure at zero?

Because a cumulative balance that equals this period’s balance is not a cumulative balance, and printing it as one invites it to be read as one. Enter the running total from the end of the last period, with its sign, and the row appears. The cumulative figure is the one that matters clinically: a patient can run minus 400 mL every day for a week and look unremarkable on each day’s chart while being nearly three litres down on the week, and the only place that is visible is the running total.

The measured rows say positive and the full calculation says negative. Which is right?

Neither, on its own. A sign that flips when an estimate is included means the chart is close enough to zero that it does not determine which side the patient is on, and the page says so in the result note when it happens. Report both figures and the insensible assumption, look at the cumulative balance across several periods where the estimate’s errors partly cancel, and weigh the clinical signs — weight, perfusion, the urine trend — more heavily than a single day’s arithmetic. A balance of plus 610 or minus 190 mL is, in practice, one of about zero.

Why does the period change the urine output figure so much?

Because the hours are a divisor. The same 900 mL of urine is 0.54 mL/kg/h in a 70 kg patient over 24 hours and 1.07 mL/kg/h over 12 hours, and only one of those crosses the oliguria threshold. Enter the period the urine was actually collected over, not the period you wish it were. The same arithmetic applies to the insensible row, which is entered per 24 hours precisely so that it scales correctly when the period is a shift rather than a day.

Which weight should I use for the mL/kg/h figure?

A measured weight if there is one. In a patient who has gained several litres, the admission weight is usually the better denominator, because today’s weight includes the retained fluid you are trying to assess and using it understates the output per kilogram. In obesity the question of which weight to use for a urine output has no settled answer and a figure calculated on actual body weight will understate output relative to one calculated on an ideal or adjusted weight. The medical vertical carries dedicated pages for ideal, adjusted and dosing weight selection; for a urine output it is enough to say which weight you used.

Does this page stage acute kidney injury?

No. It converts the urine row into mL/kg/h and tells you which side of the 0.5 and 0.3 mL/kg/h thresholds it falls on for the period you entered. Every KDIGO urine criterion also specifies a duration — 6 to 12 hours, 12 hours, 24 hours — and one period’s total cannot establish a duration. KDIGO also has creatinine criteria that this page knows nothing about. For the urine figure interpreted in its own right use the urine output calculator, and for staging use the whole picture and the full criteria.

Does it tell me how much fluid to give?

No, and that is deliberate across this whole group of pages. Prescribing fluid requires the indication, the examination, the electrolytes, the comorbidity and a judgement about what balance is wanted — and the wanted balance is negative in some patients and positive in others. This page adds up a chart that has already been written and makes the sign of the answer unmistakable. What to do about it is a clinical decision.

Related calculators

References

K. Brandis, Fluid Physiology, section on insensible water loss, for the figures used on this page: transepidermal loss “about 400 mls in an adult”, respiratory tract loss “also about 400 mls/day in an unstressed adult”, a combined minimum of “about 800 mls/day”, and the note that “an estimate of 50 mls/hr has been suggested for use in unstressed hospitalised patients”. The 500 to 1,000 mL working range quoted on the page brackets that 800 mL figure and is presented as a range, never as a point value. Cited, not reproduced.
University of Texas Medical Branch paediatric core teaching material on maintenance fluid requirements in disease, for the adjustments: “Add 10% to the transcutaneous loss replacement for every degree temperature above 38 °C”, “Add 20-50% to the respiratory replacement” for hyperventilation, and that on humidified oxygen “respiratory water loss is nil”. Quoted as the direction and rough size of the adjustment, and the page asks the reader to set the total rather than applying these multipliers itself, because applying them would produce exactly the three-significant-figure insensible loss the page argues against.
KDIGO 2012 Clinical Practice Guideline for Acute Kidney Injury, Section 2 (AKI Definition), Kidney International Supplements 2(1):19-36, for the urine output criteria reproduced in the second table: stage 1, urine output below 0.5 mL/kg/h for 6 to 12 hours; stage 2, below 0.5 mL/kg/h for 12 hours or more; stage 3, below 0.3 mL/kg/h for 24 hours or more, or anuria for 12 hours or more. Oliguria below 0.5 mL/kg/h. The thresholds are stated with their durations attached and nothing on this page stages anything, because a single charting period cannot satisfy a criterion that specifies 6, 12 or 24 hours, and because the guideline’s creatinine criteria are not on this page at all.
A. Jeyapala and colleagues, quality improvement report in BMJ Open Quality 6(2):e000006 (2017), from a UK major trauma centre, for the completeness figures: at baseline in January 2016 “only 12% of patients with fluid charts had a running 24 hourly total fluid balance documented”, six-hourly urine output was recorded for 36 per cent and a patient weight for 8 per cent; a quality-improvement intervention raised running totals from 12 per cent to 72 per cent and they then fell back to 32 per cent. The paper documents incompleteness rather than arithmetic error, and the page says so rather than claiming an error rate it has no source for.
Interpretation of the urine figure on its own is deliberately not on this page. The medical vertical’s urine output calculator was checked before this page was written and covers it, including the weight questions and the staging thresholds. This page totals a chart and links out for that, which is the same boundary the reconstitution page keeps with the dilution calculators.
The arithmetic here is addition, subtraction and two divisions; none of it reproduces a copyrighted instrument, a chart layout or a scoring system. The one judgement embedded in it is that the insensible allowance is scaled from a per-24-hour figure rather than entered per period, which was chosen because entering it per period is the error that produces a factor-of-two mistake on a shift chart.

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.