Protein Intake Calculator
Daily protein for your body weight and training goal, shown as the published range it actually is — the RDA baseline for general health, or the sports-nutrition position-stand ranges for people who train — with the source of each range named next to the number.
Daily protein range
Example: 70 kg, building muscle → 98–140 g/day (ISSN 1.4–2.0 g/kg).
Why the answer is a range with a source attached
Most of the calculators on this site implement an equation: you supply measurements, a formula fitted to a study population returns an estimate. This one does something different, and the difference is worth being upfront about. It performs a single multiplication — body weight times a published per-kilogram figure — and every bit of the content sits in the figure rather than in the arithmetic. So the honest output is not "your protein number". It is the band that was published, together with the name of the body that published it and the question that body was answering.
There are three such figures behind this tool, and they answer three different questions. At 70 kg the general-health goal returns 56 g/day, the regular-training goal returns 84–140 g/day, and the muscle goal returns 98–140 g/day — all computed at build time by the same functions the calculator runs in your browser. Averaging those three into one number would produce a figure no committee published and no reader could trace back to a source, which is a poor trade for the appearance of precision.
The companion guide — protein and water: what the reference values actually say — is the longer read on this distinction, including why a reference value is a different kind of object from a fitted equation, and why the water calculator on this site multiplies nothing by body weight at all.
The RDA is a minimum, not an optimum
The figure that circulates as "the recommended protein intake" — 0.8 g per kg of body weight per day — is the RDA from the NASEM Dietary Reference Intakes, and its definition is narrower than the phrase suggests. It is a minimum that prevents deficiency in nearly all healthy adults. It is not an optimum, and the distinction is not a technicality.
In ordinary speech, "recommended" names the amount worth aiming for. In the reference-value sense it marks the level set high enough that almost nobody in a healthy adult population falls short. A floor is conservative in one direction only: it is built so that deficiency is unlikely across a population, and it says nothing about whether more would do anything, because that was never the question it was constructed to answer. The clearest evidence that it was a different question is structural rather than rhetorical — separate sports-nutrition position stands exist, and they publish higher ranges at the same body weight for people who train.
That shape shows up in the output. At the general-health goal the minimum and the maximum come back as the same number, because 0.8 g/kg/day is a point value rather than a band, so the calculator presents it as "at least 56 g/day" at 70 kg rather than as a range. Reading a floor as a lower bound is the correct reading. Reading it as a destination is the common one.
Two position stands, and what each band claims
For people who train, two documents supply bands rather than a point, and the calculator names both rather than merging them:
- Regular training, endurance or mixed: 1.2–2.0 g/kg/day — Academy of Nutrition and Dietetics / Dietitians of Canada / ACSM position stand (2016).
- Building or maintaining muscle: 1.4–2.0 g/kg/day — ISSN position stand on protein and exercise (2017).
Set side by side at 70 kg, those bands have a property worth noticing: their upper bounds coincide. The training band runs 84–140 g/day and the muscle band runs 98–140 g/day, so switching between the two goals moves only where the band starts, never where it ends — 56 g/day of width against 42 g/day. The RDA figure of 56 g/day sits 42 g/day below the bottom of the muscle band. That gap between a deficiency floor and a training range is exactly why the tool asks which question you are asking before it answers.
Whichever band is selected, the result carries its attribution: for the training goal the calculator prints "Academy of Nutrition and Dietetics / Dietitians of Canada / ACSM position stand (2016)" alongside the numbers. A figure travelling with its provenance can be checked against the document it came from. A figure without one cannot, which is the whole difference between a reference value and a rumour with decimal places.
Worked examples at two goals and two body weights
Because the model is one multiplication, watching it move is the fastest way to see what it does and does not contain. Two goals, two body weights, every figure produced by the engine at build time:
- 70 kg, general health → at least 56 g/day (a point value, so the minimum and maximum are the same figure).
- 70 kg, building or maintaining muscle → 98–140 g/day.
- 90 kg, general health → at least 72 g/day.
- 90 kg, building or maintaining muscle → 126–180 g/day.
Adding 20 kg of body weight moves the muscle floor by 28 g/day, and it would move it by the same amount again at the next 20 kg, because a straight line is all this model is. A point value stays a point value at every weight, and a band stays the same proportion of the weight it was multiplied by. Nothing in the calculator knows anything else about the person the weight belongs to — which is the useful thing to understand about it, and the reason the accompanying text does more work than the arithmetic.
The per-serving figure is a distribution guide, not a ceiling
Alongside the daily band, the engine returns one distribution figure: 0.25 g per kg of body weight per serving, which is 18 g at 70 kg and 23 g at 90 kg — rounded to whole grams here exactly as the result box rounds them. Two things about the figure are easy to get backwards.
The first is what kind of guide it is. It is a distribution guide rather than a ceiling: it describes spreading intake across meals; it is not a per-serving limit, and the calculator makes no claim about servings above it.
The second is where it sits in the arithmetic. It is computed from body weight alone, so changing the goal moves the daily band and leaves the per-serving figure exactly where it was. Neither output is computed from the other: each is body weight times its own published constant, so they move together only because they share an input. Beyond that per-serving figure the calculator makes no claim about timing.
What "per kilogram of body weight" leaves out
All three ranges are expressed per kilogram of total body weight, so the same multiplication applies whatever that weight is composed of. Weight-based scaling of any kind is blind to composition — the same limitation that makes BMI a screening ratio rather than a body-fat measure, arriving here through a different door. The body-fat calculator estimates composition by a different method entirely, from different inputs, and this page's arithmetic does not consult it.
Protein grams also occupy part of a calorie budget, at the definitional 4 kcal per gram. The macro calculator approaches the same nutrient from that side — as a share of a daily calorie total rather than as a multiple of body weight — and the two approaches will not generally land on the same number, because they are answering different questions from different starting points. Calorie needs explained covers how the calorie total underneath the split is itself an estimate with a band around it.
Where these ranges stop applying
Every figure on this page describes healthy adults. Kidney disease and other medical conditions change protein needs — that is not a footnote to the ranges, it is a boundary on who the ranges describe at all, which is why the caveat sits next to the result rather than in small print at the bottom.
The calculator's inputs make the same point structurally. It asks for a body weight and a goal, and nothing else: no age, no health status, no medication, no laboratory value. A tool with two inputs cannot account for anything it was never given, and this one does not pretend to. It accepts weights from 10 to 500 kg, converts imperial entries to kilograms first so the two unit modes cannot quietly disagree, and rejects anything outside that range with an explanation rather than a wrong answer.
Everything runs in your browser — nothing you enter is transmitted or stored — and every worked example above is produced by the same functions at build time, so the copy on this page and the code behind the form cannot drift apart. If they ever disagreed, the site would fail to build rather than publish the disagreement.
Frequently asked questions
Where do these ranges come from?
The 0.8 g/kg/day baseline is the RDA from the NASEM Dietary Reference Intakes — a minimum that prevents deficiency in nearly all healthy adults. The 1.2–2.0 g/kg/day training range is the 2016 joint position stand of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the ACSM. The 1.4–2.0 g/kg/day muscle range is the ISSN position stand on protein and exercise (2017). The calculator prints the attribution for whichever band it is reporting, next to the band.
Is the RDA the "optimal" amount?
That is not what the figure was defined to mean. It is a minimum set high enough that deficiency is unlikely across a healthy adult population — not an optimum, because an optimum was not the question it was constructed to answer. The clearest sign that it was a different question is that separate sports-nutrition position stands exist and publish higher ranges at the same body weight for people who train. That is why the calculator reports the general-health goal as "at least" a figure rather than as a target.
Why does the calculator show a range instead of one number?
Because the published sources are ranges, and they were written to answer different questions. Averaging them together would produce a figure no committee published and nobody could trace back to a source. The tool shows the band that belongs to the selected goal and prints the basis for that band beside it, so the number travels with its provenance.
Does it matter when I eat the protein?
The engine returns exactly one distribution figure: 0.25 g per kg of body weight per serving. It is a distribution guide rather than a ceiling — it describes spreading intake across meals, not capping any one of them. It depends only on body weight, so switching goals moves the daily band and leaves the per-serving figure untouched. Beyond that figure the calculator makes no claim about timing, and it is not the kind of tool that could.
Do these ranges apply if I have kidney disease?
They describe healthy adults. Kidney disease and other medical conditions change protein needs, which is a boundary on who these ranges describe at all rather than a footnote to them. The calculator asks for a body weight and a goal and nothing else — it has no input for health status, so it cannot take one into account. Setting protein intake in that situation belongs with a qualified healthcare professional.
Should I use total body weight even if I carry a lot of fat?
The published ranges are stated per kilogram of total body weight for healthy adults, and total body weight is what the calculator multiplies. That multiplication is blind to how the weight is composed — the same limitation that makes BMI a screening ratio rather than a body-fat measure. What applies to a particular person is a judgement for a qualified professional rather than for a calculator.
What body weights does the calculator accept?
From 10 to 500 kg, with imperial entries converted to kilograms first so the two unit modes cannot disagree. Anything outside that range returns an explanation instead of a number. Because the arithmetic is a single multiplication, results scale linearly with weight — nothing in the model bends at any point in between.
Not medical advice: this calculator provides general educational information about published population reference ranges. It cannot account for your individual health context and must not be used to diagnose or treat any condition — consult a qualified healthcare professional, particularly with kidney disease or any medical condition affecting protein handling. Values are processed locally in your browser and never transmitted. See the methodology page.