Protein Intake Calculator — grams per day from bodyweight

How it works

Protein is the one macronutrient consumer guidance doses by bodyweight rather than as a percentage of energy. The reason is that protein requirements track lean tissue, which scales with body size, while your calorie intake varies with activity — so a share-of-calories target would move your protein around for reasons that have nothing to do with how much you need. That is why this page exists separately from the macro calculator: same nutrient, genuinely different model.

The rates come from the International Society of Sports Nutrition's 2017 position stand. Its second numbered position is that 1.4–2.0 g/kg/day is sufficient for building and maintaining muscle in most exercising individuals. The wider 1.2–2.4 g/kg/day range carries less weight and we flag that here: it appears in the stand's discussion rather than its numbered positions, describing what endurance and strength/power athletes ate in studies of preserving lean mass while cutting calories hard. Treat it as the territory trained athletes occupy, not a recommendation aimed at you.

The RDA of 0.8 g/kg/day is stated by both sources independently — the ISSN stand says it outright, and the National Academies' own reference tables carry it in a footnote ("for adults 0.8 g/kg body weight for the reference body weight"). Their published gram figures agree: the protein RDA for men aged 19–30 is 56 g/day, which is 0.8 × 70 kg.

Worked example

A 70 kg adult at the RDA needs 70 × 0.8 = 56 g/day — matching the National Academies' published 56 g/day for men aged 19–30, which is what the RDA was derived from.

An 82 kg lifter building muscle falls in the 1.4–2.0 g/kg band: 82 × 1.4 = 115 g/day at the low end and 82 × 2.0 = 164 g/day at the top. The whole range is a target zone, not a progression to climb.

Per serving, the position stand suggests 0.25 g/kg of high-quality protein, so the 82 kg lifter is looking at about 21 g per feeding — consistent with the absolute 20–40 g the same statement gives.

Frequently asked questions

Is the RDA enough protein?

For general health in a healthy adult, yes — that is precisely what an RDA means: the amount meeting the requirements of nearly all healthy people. What it is not is an optimum for every goal. If you are training to build muscle, losing weight while trying to preserve lean mass, or older and concerned about muscle loss, the higher published ranges exist for those reasons.

Why is protein dosed per kilogram instead of as a percentage of calories?

Because the need scales with your body, not your appetite. Two people of the same weight eating 1,800 and 3,000 calories have similar protein requirements, but a fixed percentage would give the second person far more. The National Academies do publish a percentage range for protein — 10–35% of energy — but it is wide, and per-kilogram dosing is the more useful form for an individual.

Can I eat too much protein?

For healthy adults, high intakes within the published ranges have not been shown to cause harm, and the position stand notes intakes above 3.0 g/kg/day have been studied in resistance-trained people. The important exception is kidney disease, where protein intake is often deliberately restricted — if you have reduced kidney function, the target here does not apply and your clinician's advice does.

Does the source of the protein matter?

Yes, though this page doesn't model it. The per-serving figure specifically refers to high-quality protein — sources with a complete essential amino acid profile and good digestibility. Plant proteins vary more in amino acid pattern, so people eating mostly plant sources often aim slightly higher, and combine sources across the day.

How should I spread it across the day?

The position stand suggests spreading protein evenly, roughly every 3–4 hours, rather than concentrating it in one meal. The per-serving output here is the 0.25 g/kg figure that guidance is built on. Total daily intake matters most; the distribution is a secondary refinement.

Should I use my bodyweight or my lean mass?

This page uses total bodyweight, which is what the published ranges are stated against. Some practitioners dose by lean body mass instead, particularly for people carrying a lot of fat mass, where a total-bodyweight target can come out higher than needed. If that applies to you, the body fat calculator gives you a lean mass estimate to work from.

What does this exclude?

It excludes pregnancy and lactation, which raise protein needs; children and adolescents, whose requirements differ by age; illness, injury and surgical recovery; and any kidney or liver condition affecting protein handling. It also says nothing about your total calories or the rest of your diet — use the macro calculator to see how a protein target fits alongside carbohydrate and fat.