Protein Calculator

Working it out by hand

One profile, every mode the calculator has. A body weight of 180 lb, four eating occasions, and a daily energy figure of 2,400 kcal for the percentage row. The arithmetic is the same in each mode; only the g/kg figure changes, and each of those figures is the published range named beside it.

Step 1, the unit conversion. Every range on this page is expressed per kilogram, so a weight in pounds is converted first: 180 × 0.45359237 = 81.6466 kg. That factor is exact by definition of the international pound, so nothing is lost here. The calculator keeps the unconverted digits and rounds only for display, which is why hand-working from a rounded 81.65 kg lands a few hundredths away from what the panel shows.

Step 2, multiply by the range. Grams per day is body weight in kilograms times grams per kilogram. The planning figure the panel shows is the midpoint of the range, and it carries no more authority than the range around it.

• General health, the 1.2 to 1.6 g/kg serving goal published in the Dietary Guidelines for Americans 2025-2030: 81.6466 × 1.2 = 97.98 g and 81.6466 × 1.6 = 130.63 g, midpoint 114.31 g at 1.4 g/kg.
• Weight loss, 1.2 to 2.0 g/kg, the same lower bound with an upper bound from the 2016 ACSM, Academy of Nutrition and Dietetics and Dietitians of Canada position on energy restriction: 97.98 g to 163.29 g, midpoint 130.63 g.
• Muscle gain and strength, 1.6 to 2.2 g/kg, from where Morton and colleagues found gains plateau to the top of that confidence interval: 130.63 g to 179.62 g, midpoint 155.13 g.
• Endurance training, the same 1.2 to 2.0 g/kg athlete range from the 2016 position: 97.98 g to 163.29 g, midpoint 130.63 g. It matches the weight loss band because the published ranges match, not because the modes were merged.
• Custom, whatever figure you were given. At 1.8 g/kg: 81.6466 × 1.8 = 146.96 g, a single number rather than a range, because you supplied a point and the calculator will not invent a band around it.

Step 3, the derived rows. Taking the general health midpoint of 114.31 g: energy is 114.31 × 4 = 457.24 kcal, using the Atwater factor of 4 kcal per gram that US nutrition labelling uses. Against a 2,400 kcal day that is 457.24 ÷ 2,400 = 19.05%. Split across four eating occasions it is 114.31 ÷ 4 = 28.58 g each. Per pound rather than per kilogram the same figure is 0.6351 g/lb.

For comparison the calculator also shows two figures it does not treat as goals. The adult RDA of 0.8 g/kg works out to 65.32 g here, and the 1 gram per pound rule of thumb works out to 180 g, which is 2.2046 g/kg.

What 1 gram per pound actually means

It is the most repeated number in fitness, and it is a rule of thumb rather than a published recommendation. One gram per pound is about 2.2 grams per kilogram — roughly 38% above the top of the federal serving goal, and at or just past the upper edge of what the muscle-gain evidence supports.

It is easy arithmetic, which is most of why it spread. For someone training hard it lands in a defensible place. For most other adults it is more protein than the evidence asks for. The calculator shows it every time so you can see where it sits against your own goal rather than guessing.

Protein and weight loss

Protein does not cause weight loss. Energy balance determines whether body weight goes up or down. What higher protein intake is associated with, while eating in a deficit, is holding on to more lean mass and feeling fuller — both of which can make a deficit more sustainable. That is worth having, and it is a different claim from "protein burns fat".

One limitation worth naming: applying grams per kilogram to total body weight can overstate needs at higher body-fat levels, because protein requirements track lean mass more closely than total mass. The calculator flags weights outside its typical band rather than quietly substituting a different figure.

Protein and muscle gain

Protein supports the adaptation that training drives. It does not build muscle on its own, and eating more of it past a point does not produce more. The pooled evidence puts that point at roughly 1.62 g/kg per day, with the confidence interval reaching about 2.2. Training stimulus and adequate total energy matter more than the last 20 grams.

Splitting protein across the day

Spreading protein across meals rather than loading it into one is supported, and the current Dietary Guidelines put it in a section headed "Prioritize Protein Foods at Every Meal". What is not settled is the per-meal number. The ACSM joint position statement points to roughly 0.25–0.3 g/kg or 15–25 grams per occasion; the ISSN position stand points to 0.25 g/kg or 20–40 grams every three to four hours. Those do not agree.

Because of that, the per-occasion figure here is your daily total divided by the number of occasions you enter. It is a planning split, not a physiological threshold.

Assumptions and limitations

• It uses the weight you type. No ideal weight, goal weight or lean mass is substituted behind your back.
• Ranges are population figures. They come from guidance and pooled research about groups of people. Individual needs vary, and none of these sources claims otherwise.
• Age, sex and height are not collected. The ranges cited here are published per kilogram of body weight and are not stated separately by age, sex or height, so this calculator has nothing to apply them to. That is a limit of what the sources provide rather than a finding that those factors do not matter. Older adults in particular are an active question in the literature, and one of the documents cited below is about exactly that.
• Protein quality and source are not modelled. Total grams is the question here.
• This is a general adult nutrition estimate, not a medical nutrition prescription.

Edge cases

• Per kilogram is not per pound, and the gap is large. One gram per pound is 2.2046 g/kg, so the two units differ by a factor of about 2.2. Applying a per-kilogram figure to a weight in pounds is the most expensive mistake available here: at 180 lb, 1.6 g/kg is 130.63 g, while 1.6 times 180 is 288 g. The calculator converts for you, and shows the g/lb equivalent beside the g/kg one so the two are never confused.
• Why two calculators disagree. Almost never the arithmetic. Multiplying a weight by a coefficient is not where tools differ; the coefficient is. A calculator using 0.8 g/kg and one using 2.2 g/kg will differ by a factor of nearly three on identical input, and both can be quoting a real published figure for a different question. That is why every range here names the document it came from, so the choice is visible rather than baked in.
• It uses total body weight, not lean mass. Every range on this page is published per kilogram of body weight, so that is what the calculator multiplies. Protein needs track lean mass more closely than total weight, which means the figure fits less well the further body composition sits from the populations the source research was drawn from. The panel says so when a weight falls outside the band most of that work used.
• An empty field is not a zero. A blank or unreadable weight leaves the calculator waiting rather than reporting 0 g. A weight of zero or below is refused outright, as is anything below 35 kg or above 350 kg, because at those extremes the input is more likely to be an error or a person outside this calculator's stated scope than a figure it should answer.
• One broken optional field does not wipe the answer. Eating occasions must be a whole number from 1 to 12. Something else there suppresses only the per-occasion split, and an unusable calorie figure suppresses only the percentage row. The daily range, the g/kg figures and the comparisons do not depend on either, so they stay.
• The midpoint is arithmetic, not a recommendation. The planning figure is the middle of the published range and nothing more. Custom mode has no range to take a middle of, so it returns the single number you entered.

Your numbers stay in the page

The weight, goal, eating occasions and calorie figure you enter are processed by this page in your browser. They are not sent to a server, not stored after you close the tab, and not visible to anyone else. There is no account and nothing to sign up for.

Who should not use this calculator on its own

Protein needs in these situations are individual, and some of them involve deliberately limiting protein under supervision. A general formula can produce a number that is actively wrong. Please work from advice given to you by a clinician or registered dietitian rather than from this page:

• Children and anyone under 18
• Pregnancy
• Breastfeeding
• Chronic kidney disease not on dialysis, where protein is often restricted
• Anyone on dialysis, where needs are usually higher and are prescribed
• Liver disease
• A current or past eating disorder
• Any medically prescribed diet — the prescription overrides this calculator

Sources, assumptions, and review

Every number this calculator publishes comes from one of the following. Each is linked to the specific figure it supports.

• Adult RDA, 0.8 g/kg — National Academies, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005). A minimum-requirement reference from nitrogen-balance data.
• Protein serving goal, 1.2–1.6 g/kg — Dietary Guidelines for Americans 2025-2030, which states: "Protein serving goals: 1.2–1.6 grams of protein per kilogram of body weight per day, adjusting as needed based on your individual caloric requirements."
• The disagreement about that goal — the American Society for Nutrition published a Perspective arguing the evidence does not yet justify applying a higher-protein recommendation to every adult across the lifespan. That view is not settled either way, and you should know it exists.
• Athlete range 1.2–2.0 g/kg, energy restriction, and per-meal figures — Academy of Nutrition and Dietetics, Dietitians of Canada and ACSM, Nutrition and Athletic Performance (2016).
• 1.4–2.0 g/kg for exercising adults, and per-meal dosing — International Society of Sports Nutrition position stand: protein and exercise (2017).
• The 1.62 g/kg plateau for muscle gain — Morton et al. (2018), British Journal of Sports Medicine, a systematic review and meta-regression of 49 studies.

This calculator provides a general adult nutrition estimate, not a medical nutrition prescription. It has not been reviewed by a physician or a dietitian, and it does not claim to have been. What it does instead is show you every source behind every number, so you can check the reasoning yourself or take it to someone who can.

Related calculators

• Macro calculator — split a daily calorie target across protein, carbohydrate and fat.
• TDEE calculator — estimate the daily energy expenditure your calorie target sits inside.
• Calorie deficit calculator — size a deficit if weight loss is the goal.
• Lean body mass calculator — estimate lean mass if you want a different basis for your target.
• All health calculators.