Enteral Feed Rate Calculator: mL per Hour and Hours to Target

Millilitres an hour for a tube feed, from the energy target, the feed’s energy density and the feeding schedule — with the daily volume, the water the feed actually contributes, and the protein it delivers. A rest period changes the rate by exactly the ratio of hours and not the volume, and the page shows that explicitly.

Last updated 1 Oct 2026

These figures come from published predictive equations and reference ranges. They are not a measurement of the person in front of you, and they are not a feeding prescription — they are a starting estimate for a dietitian or clinician to weigh against the patient, the local policy and, where it is available, measurement.

Tube feed rate from target and density

target, energy density and schedule → mL/h, daily volume, feed water and protein

Energy target (kcal/day)The daily energy figure you are feeding to, in kilocalories. This page does not estimate it — it takes it as given, because an energy target is a judgement made elsewhere from a predictive equation or from indirect calorimetry. If you want the figure in kilojoules instead, divide by 4.184.

Feed energy densityPrinted on the pack, usually as “kcal/ml” or “Cal/mL”. Read it rather than assuming: a feed sold as standard may be 1.0 or 1.06 kcal/mL depending on the brand, and the difference between 1.0 and 1.5 is a third off the volume and a third off the water. Choose Custom and type the figure if your feed is not one of the four.

Custom energy density (kcal/mL)Only used when the selector above is set to Custom. Locked otherwise, so the density you can see is always the density the page used. A density of 0 is refused rather than divided by.

Feeding scheduleA rest period is the usual arrangement: feeds commonly run 16 to 20 hours with a break, which lets gastric pH recover, leaves time for mobilisation and physiotherapy, and fits the drug round. It changes the RATE, not the volume — the same litres have to go in over fewer hours.

Daily rest period (hours)Hours in each 24 with the feed off. 4 hours gives a 20-hour feed, 6 gives 18, 8 gives 16. A rest of 24 hours or more leaves no feeding time at all and the page refuses rather than dividing by zero.

Feeding hours per dayUsed only when the schedule above is set to a fixed number of feeding hours. Locked otherwise. This is the same arithmetic as a rest period, entered from the other end: 16 feeding hours and an 8-hour rest are the same schedule.

Water content of the feedThe typical figures this page uses are 84 per cent below 1.15 kcal/mL, 82 per cent from 1.15 to 1.35, 77 per cent from 1.35 to 1.8 and 70 per cent at 1.8 and above, each taken from two independent manufacturers’ published compositions. They are typical, not universal. If the pack states the water content, type it — the figure matters, because feed water is the larger part of most tube-fed patients’ intake.

Water content from the pack (% of volume)Only used when the selector above says you will type it. Manufacturers usually publish this as millilitres or grams of water per 100 mL, which is the same number as a percentage. Values run from about 85 per cent in a standard feed down to about 69 per cent in the most concentrated.

Feed protein content (g per 100 mL) — optionalFrom the pack. Set to 0 to hide the protein rows. Typical values run from about 4 g per 100 mL in a standard feed to about 7.5 g per 100 mL in a concentrated one, and high-protein variants of the same density exist — so this is a per-product number and not a function of the density. The protein and nitrogen it works out to use the same 6.25 factor as the protein requirement page, so the two agree.

A rate you want to check (mL/h) — optionalLeave at 0 unless you are checking a rate that is already set or that you are proposing. The page then works out how many hours that rate needs to deliver the whole daily volume, and what percentage of the energy target it would actually meet within the feeding hours you have.

100.0mL/hExample

a 2,000 kcal/day target on a 1.0 kcal/mL standard feed with a 4-hour rest period, feed protein 4.0 g per 100 mL

Volume from energy, rate from hours, and the water that comes with it

V_day = E/ρ · mL/h = V_day/H · H = 24 − R · rate multiplier = 24/H · water = V_day × f_w · protein = V_day × p/100 · g N = protein/6.25 · hours at a chosen rate = V_day/rate

E: the daily energy target in kcal. Taken as given; this page does not estimate it
ρ: the feed’s energy density in kcal/mL, from the pack. The whole page divides by it, so a density of 0 is refused rather than answered
V_day: the daily feed volume in mL. Note what it does NOT depend on: the schedule. The volume is fixed by the target and the density alone, which is why a rest period changes the rate and nothing else
H, R: feeding hours and rest hours in each 24, so H = 24 − R. The rate is inversely proportional to H and the multiplier against a continuous feed is exactly 24/H: a 20-hour feed runs 1.2 times the continuous rate, an 18-hour feed 1.333 times, a 16-hour feed 1.5 times
f_w: the water fraction of the feed by volume. Typical published values are about 84 per cent at 1.0 kcal/mL, 82 per cent at 1.2, 77 per cent at 1.5 and 70 per cent at 2.0. Feed water is not the same as feed volume and a concentrated feed delivers far less of it for the same energy
p: the feed’s protein content in g per 100 mL, from the pack. Protein per 100 kcal is p/ρ, which is the figure to compare between feeds of different densities

Worked example

a 2,000 kcal/day target on a 1.0 kcal/mL standard feed with a 4-hour rest period, feed protein 4.0 g per 100 mL
Volume first, because the volume does not care about the schedule: 2,000 kcal ÷ 1.0 kcal/mL = 2,000 mL a day. Two litres, which at a litre a pack is two packs.
Feeding hours: 24 − 4 = 20 hours. The rate is the volume over the hours: 2,000/20 = 100 mL an hour.
Now the check that matters, because it is the one people get wrong. Run the same 2,000 mL continuously over 24 hours and the rate is 2,000/24 = 83.3 mL an hour. The rest period has multiplied the rate by 24/20 = 1.2 exactly, and has changed nothing else at all: the same 2,000 mL, the same 2,000 kcal, the same water, the same protein. If any of those moved when you changed the schedule, something is wrong.
Water, which is the row most often forgotten. A standard 1.0 kcal/mL feed is about 84 per cent water, so 2,000 × 0.84 = 1,680 mL of water a day — 84 mL an hour while the feed is running, and 320 mL of the volume that is not water at all. That 1,680 mL is what the feed contributes to the fluid balance; everything else has to come from flushes or a separate water prescription.
Protein: 2,000 mL × 4.0 g/100 mL = 80 g of protein a day, which is 80/6.25 = 12.8 g of nitrogen. Per 100 kcal that is 4.0/1.0 = 4.0 g of protein, and as a fraction of the energy target 80 × 4/2,000 = 16 per cent. Carry the 80 g to the protein requirement page: for a 70 kg ward inpatient on 1.0 to 1.5 g/kg/day the range is 70 to 105 g a day, so this feed at this volume lands near the bottom of it.
SWITCH TO A 2.0 kcal/mL CONCENTRATED FEED AND WATCH THE WATER COLLAPSE. The same 2,000 kcal now needs 1,000 mL, so the rate over 20 hours halves to 50 mL an hour — that part is obvious. The water does not halve. A 2.0 kcal/mL feed is about 70 per cent water rather than 84, so 1,000 × 0.70 = 700 mL of water a day against 1,680 before. The energy is identical and the water has fallen by 980 mL, which is most of a litre that someone now has to prescribe separately. That is the trade a concentrated feed makes, and it is the single most useful thing on this page.
Finally, a rate you want to check. Suppose the pump is set to 80 mL an hour on the original standard feed: over the 20 feeding hours that is 1,600 mL, which at 1.0 kcal/mL is 1,600 kcal, or 80 per cent of the target. The whole 2,000 mL at 80 mL an hour would need 25 hours — more than the day has. Either the rate goes up, the window gets longer, or the target is met over more than one day. The page prints all three figures and chooses none of them. For the pump arithmetic itself see the infusion pump rate page, and for recording what actually went in, the fluid balance chart page.

Water content by energy density, from published product compositions

Two independent manufacturers at each density, from their own published compositions. The agreement is close — 83.5 against 85 per cent, 76.4 against 78, 70 against 70 — which is why a typical figure is usable at all, but it is a typical figure and not a property of the density. If the pack states the water content, type it in rather than taking the default. Note also what the table says about protein. Protein per 100 kcal is the feed’s protein in g per 100 mL divided by its energy density, and across these seven products it runs from 3.75 g per 100 kcal (Nutrison Concentrated) to 4.64 (Osmolite 1.2 Cal), with the other five between 4.00 and 4.19. So it is loosely clustered rather than constant, it is NOT a function of the energy density, and a feed chosen to meet an energy target can land anywhere in that spread. High-protein variants of each density exist precisely because the clustering can be broken on purpose.
Energy density	Product	Water	Protein	Figure this page uses
1.06 kcal/mL	Jevity 1.0 Cal (Abbott)	835 mL/L, 83.5%	44.3 g/L	84% below 1.15 kcal/mL
1.0 kcal/mL	Nutrison (Nutricia)	85 g/100 mL, 85%	4.0 g/100 mL	as above
1.2 kcal/mL	Osmolite 1.2 Cal (Abbott)	822 mL/L, 82.2%	55.7 g/L	82% from 1.15 to 1.35
1.5 kcal/mL	Osmolite 1.5 Cal (Abbott)	764 mL/L, 76.4%	62.9 g/L	77% from 1.35 to 1.8
1.5 kcal/mL	Nutrison Energy (Nutricia)	78 g/100 mL, 78%	6.0 g/100 mL	as above
2.0 kcal/mL	TwoCal HN (Abbott)	700 mL/L, 70.0%	83.5 g/L	70% at 1.8 and above
2.0 kcal/mL	Nutrison Concentrated (Nutricia)	70 mL/100 mL, 70%	7.5 g/100 mL	as above

The same 2,000 kcal target on four feeds and three schedules

Read it across and the schedule multiplies the rate by 24/H — 1.0, 1.2 and 1.5 for 24, 20 and 16 hours — in every row identically, and leaves the volume and the water untouched. Read it down and the density divides the volume while doing something worse than dividing to the water: from 1.0 to 2.0 kcal/mL the volume halves but the water falls from 1,680 to 700 mL, a drop of 58 per cent, because the water fraction falls as well. Nearly a litre a day has to be made up from somewhere, and nothing on the feed pump will tell you that.
Feed	Daily volume	Rate over 24 h	Rate over 20 h	Rate over 16 h	Water from the feed
1.0 kcal/mL	2,000 mL	83.3 mL/h	100.0 mL/h	125.0 mL/h	1,680 mL
1.2 kcal/mL	1,667 mL	69.4 mL/h	83.3 mL/h	104.2 mL/h	1,367 mL
1.5 kcal/mL	1,333 mL	55.6 mL/h	66.7 mL/h	83.3 mL/h	1,027 mL
2.0 kcal/mL	1,000 mL	41.7 mL/h	50.0 mL/h	62.5 mL/h	700 mL

Volume, rate and water: three numbers that move independently

The volume is fixed by the target and the feed, and the schedule only moves the rate. That sentence is the whole page. Divide the energy target by the feed’s energy density and you have the millilitres that must go in; divide those millilitres by the hours available and you have the rate. Nothing about a rest period changes the volume, the energy, the protein or the water — it changes how fast the same litres go in, by exactly the factor 24 divided by the feeding hours. A 20-hour feed runs at 1.2 times the continuous rate, an 18-hour feed at 1.333, a 16-hour feed at 1.5. The page prints that multiplier and the continuous rate alongside the answer so the relationship is visible rather than something you have to trust.

Why feeds are run with a rest period at all. A break of four to eight hours lets gastric pH recover, which matters for bacterial colonisation; it leaves a window for mobilisation, physiotherapy and theatre; and it fits a drug round that often cannot be given with feed in the stomach. The cost is the higher rate, and on a patient whose tolerance is marginal that cost is real — which is why the usual move when tolerance is the problem is to go the other way and feed continuously, accepting the inconvenience for the lowest hourly rate a target allows. The page does not choose; it prices the choice.

Feed is not free water, and the arithmetic is worse than it looks. A standard 1.0 kcal/mL feed is about 84 per cent water by volume. A concentrated 2.0 kcal/mL feed is about 70 per cent. Those figures come from the manufacturers’ own published compositions and two independent brands at each density agree closely, which is what makes a typical figure usable at all. Now put them together with the volumes. The same 2,000 kcal is 2,000 mL of standard feed, contributing 1,680 mL of water, or 1,000 mL of concentrated feed, contributing 700 mL. Switching to the denser feed does not halve the water — it removes 58 per cent of it, because the volume halves and the fraction falls too. That missing litre has to be prescribed, and it is the commonest way a tube-fed patient ends up quietly dehydrated on a feed that meets its energy target perfectly. The page prints the water figure in millilitres a day and per hour of feeding for exactly that reason.

Protein does not come along with the energy. Meeting an energy target says nothing about whether the protein target is met, because protein per 100 kcal varies between products at the same density and high-protein variants exist precisely so that it can be chosen separately. The page takes the feed’s protein content from the pack, works out the grams and the nitrogen delivered at the volume it has calculated, and expresses it per 100 kcal so feeds of different densities can be compared. It uses the same 6.25 nitrogen factor as the protein requirement page and the parenteral macronutrient page, deliberately, so a reader moving between the three never finds two answers to the same arithmetic. Carry the grams of protein across and compare them against the range for the condition; if the feed under-delivers, that is a reason to change the feed rather than to raise the rate.

What this page will not do. It will not estimate an energy target — that is a judgement made from a predictive equation or from indirect calorimetry, and it belongs on the energy requirement page rather than here. It will not tell you a tolerable rate, decide how fast to build up, or say anything about how quickly feeding may be introduced in someone at risk of refeeding syndrome: that last question is answered on the refeeding syndrome risk interpreter and it governs everything on this page for the first few days. It refuses to answer on a feed with no energy in it, on a target of zero, and on a rest period of 24 hours or more, because each of those is a division by nothing dressed up as a question. For what actually went in rather than what was planned, use the fluid balance chart page; for a pump rate expressed as a dose, the infusion pump rate page; and for the paediatric case, which this page does not cover at all, the paediatric maintenance fluid page.

Frequently asked questions

Does a rest period change the volume or just the rate?

Only the rate, and by exactly the ratio of the hours. The daily volume comes from the energy target divided by the energy density and has nothing to do with the schedule, so the same millilitres simply go in over fewer hours. The multiplier is 24 divided by the feeding hours: 1.2 for a 20-hour feed, 1.333 for 18 hours, 1.5 for 16. The page prints both the multiplier and the 24-hour continuous rate next to the answer so you can see that the volume, the energy, the water and the protein have all stayed put.

Why does the water content matter so much?

Because feed water is usually the largest part of a tube-fed patient’s intake, and it is not the same as the feed volume. A standard 1.0 kcal/mL feed is about 84 per cent water; a concentrated 2.0 kcal/mL feed is about 70 per cent. Meeting 2,000 kcal with the standard feed gives 1,680 mL of water, and with the concentrated feed 700 mL — the same energy and 980 mL less water. Nothing on the pump says so. If the pack states the water content, type it in rather than taking the typical figure, and compare the total against the fluid plan.

What water content should I use if the pack does not say?

The page’s defaults are 84 per cent below 1.15 kcal/mL, 82 per cent from 1.15 to 1.35, 77 per cent from 1.35 to 1.8 and 70 per cent at 1.8 and above. Each comes from two independent manufacturers’ published compositions and the two agree closely at every density — 83.5 against 85 per cent at standard strength, 76.4 against 78 at 1.5, 70 against 70 at 2.0. They are typical figures, not properties of the density, so they are a reasonable default and a poor substitute for the pack.

The protein looks low even though the energy target is met. Why?

Because the two are independent. Protein per 100 kcal is a property of the individual product, not of its energy density, and a feed can meet an energy target while under-delivering protein against every range on the protein requirement page. That is why high-protein variants of each density exist. The page prints the protein delivered, the nitrogen it works out to, and the protein per 100 kcal so feeds can be compared; if the figure is short, the answer is usually a different feed rather than a higher rate.

Why will it not give an answer when I put 0 in the energy density?

Because the whole page divides by it. A feed with no energy in it cannot meet an energy target, and the arithmetic would produce an infinite volume or a plausible-looking enormous one. The same applies to a target of zero and to a rest period of 24 hours or more, which leaves no feeding time in the day. A page that answers a meaningless question with a number is worse than one that declines, so it declines.

Can I enter the target in kilojoules?

Not directly — the field is kilocalories. Divide a kilojoule figure by 4.184 first. This is worth care because a kilojoule figure entered as kilocalories is 4.184 times too large and produces a volume and a rate that are wrong by the same factor: an 8,400 kJ target typed in as 8,400 would ask for 8.4 litres of standard feed a day and a rate above 400 mL an hour, which is why the top band on this page says to check for exactly that.

How do I use the rate field?

Put in a rate that is already set or that you are proposing, and the page works out two things: how many hours that rate would need to deliver the whole daily volume, and how much volume and energy it actually delivers within the feeding hours you have set, as a percentage of the target. A rate that needs more than 24 hours cannot meet the target at all. Leave the field at 0 to hide those rows.

Does this page say how fast to build up to the target?

No, and deliberately not. How fast feeding may be introduced is a clinical decision that turns on refeeding risk, on gastrointestinal tolerance and on the electrolytes, and it is the one part of starting a feed where getting it wrong is dangerous rather than merely inefficient. Refeeding risk is assessed on the medical refeeding syndrome risk interpreter, linked above. This page tells you what the full target would require; it has no opinion on when to get there.

Related calculators

References

Abbott Nutrition, published product compositions for Jevity 1.0 Cal, Osmolite 1.2 Cal, Osmolite 1.5 Cal and TwoCal HN. Source for four of the seven water-content figures in the table above, each read from the manufacturer’s own nutrient panel: 835 mL water per litre at 1.06 kcal/mL, 822 mL/L at 1.2, 764 mL/L at 1.5 and 700 mL/L at 2.0, with protein 44.3, 55.7, 62.9 and 83.5 g/L respectively.
Nutricia, published nutrient information for Nutrison, Nutrison Energy and Nutrison Concentrated. Independent second source at each of three densities: 85 g water per 100 mL at 1.0 kcal/mL, 78 g/100 mL at 1.5 and 70 mL/100 mL at 2.0, with protein 4.0, 6.0 and 7.5 g per 100 mL. Two manufacturers agreeing within 1.6 percentage points at every density is what makes the typical figures on this page defensible; nothing beyond that is claimed for them.
Food and Agriculture Organization of the United Nations, Food energy — methods of analysis and conversion factors (FAO Food and Nutrition Paper 77, 2003). Source for the 4 kcal/g protein energy factor used in the percentage-of-energy row, for the kcal-to-kJ factor of 4.184 referenced in the top band, and for the nitrogen-to-protein factor of 6.25 and its stated limits.
Parenteral and Enteral Nutrition Group of the British Dietetic Association, A Pocket Guide to Clinical Nutrition, 5th edition (2018), consulted via the publicly distributed protein and fluid summary. Cited for the practice this page is built around rather than for any figure: that a nitrogen requirement is converted from a protein requirement using 6.25 and that the result is “just an approximation to give a starting point, after which monitoring and adjustment are crucial”.
Derivation performed for this page rather than taken from a source: the daily volume E/ρ is independent of the schedule, so the rate over H feeding hours is E/(ρH) and the ratio to the 24-hour continuous rate is exactly 24/H whatever the target and the density. It follows that a rest period can only ever change the rate, never the volume, the water or the protein — and that the three common schedules 24, 20 and 16 hours give multipliers of exactly 1, 1.2 and 1.5. The water consequence is also arithmetic rather than opinion: water delivered is E·f(ρ)/ρ, so moving from 1.0 kcal/mL at 84 per cent water to 2.0 kcal/mL at 70 per cent multiplies the water by (70/84)/2 = 0.417, a 58 per cent reduction for identical energy.

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.