Protein Calculator
How much protein to eat a day, and how to spread it across meals so each one actually does something. If you know your body fat percentage the target is set from lean mass instead of total weight — which matters, because fat tissue has almost no protein requirement of its own.
1.8 g per kg of bodyweight, which is 540 kcal — about 1.8 g per kg of your bodyweight.
Across the day
Each meal clears the 30 g needed to fully stimulate muscle protein synthesis at your bodyweight.
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Why the basis matters
Protein requirement comes from the tissue that uses protein, and adipose tissue barely does. A fixed grams-per-kilogram rule applied to total bodyweight therefore over-prescribes to anyone carrying a lot of fat. Here is the same person both ways — 120 kg at 40% body fat, training for strength.
| Basis | Target | What it assumes |
|---|---|---|
| 1.8 g/kg of bodyweight | 216 g | That all 120 kg needs feeding, including 48 kg of fat. |
| 2.3 g/kg of lean mass | 166 g | That the 72 kg actually doing the work is what sets the requirement. |
At an average composition the two bases land within a few grams of each other, which is why the bodyweight rule survives at all. The gap opens at the extremes — and the extremes are exactly where someone is most likely to be looking up a protein target in the first place.
Spreading it across the day
Total daily intake does nearly all the work. Timing is a much smaller effect than it is usually sold as — the 30-minute anabolic window did not survive scrutiny, and muscle protein synthesis stays elevated for a day or more after training.
What does hold up is a floor per sitting. The synthetic response to a meal rises with dose and then saturates at roughly 0.4 g per kilogram of bodyweight, so meals under that are submaximal and meals well over it are not proportionally better. Three or four meals that each clear the floor beats six that do not, which is the opposite of the "eat every two hours" advice that circulated for years.
Per-meal threshold = bodyweight (kg) × 0.4 g Most useful meals = daily target ÷ that threshold
That second line is the practical constraint. A 100 kg person on 120 g a day can support three adequate feedings, not six — the calculator above works out the ceiling for your own figures and tells you when you have gone past it.
Where to get it
Protein per 100 g of food, and how much of each it takes to reach 30 g. Quality reflects digestibility and amino acid profile together: the reason 20 g from wheat and 20 g from egg are not equivalent on the plate, even though the label says the same thing.
| Food | Per 100 g | For 30 g | Quality |
|---|---|---|---|
| Chicken breast, cooked | 31 g | 97 g | high |
| Beef mince, 5% fat, cooked | 26 g | 115 g | high |
| Salmon, cooked | 25 g | 120 g | high |
| Tuna, canned in water | 24 g | 125 g | high |
| Greek yoghurt, 0% fat | 10 g | 300 g | high |
| Egg, whole | 12.6 g | 238 g | high |
| Whey protein powder | 80 g | 38 g | high |
| Soya protein isolateplant | 88 g | 34 g | high |
| Tofu, firmplant | 17 g | 176 g | moderate |
| Tempehplant | 19 g | 158 g | moderate |
| Lentils, cookedplant | 9 g | 333 g | moderate |
| Chickpeas, cookedplant | 9 g | 333 g | moderate |
| Peanut butterplant | 25 g | 120 g | lower |
| Oats, dryplant | 13 g | 231 g | lower |
| Wholemeal breadplant | 9 g | 333 g | lower |
Plant sources score lower mostly for digestibility and for being short in one essential amino acid — lysine in grains, methionine in legumes. Neither is hard to work around: eating a range across the day covers the profile, with no need to combine sources within a single meal, and adding 10 to 20% to the total compensates for the digestibility gap. Soya and pea isolates score close to animal sources unaided.
Reference intakes
The published RDAs, for comparison. These are population minimums for avoiding deficiency — not targets — which is why an adult training figure comes out two or three times larger. If the gap between these and the calculator above is surprising, that gap is the single most useful thing on this page.
| Age group | Male | Female |
|---|---|---|
| 1–3 years | 13 g | 13 g |
| 4–8 years | 19 g | 19 g |
| 9–13 years | 34 g | 34 g |
| 14–18 years | 52 g | 46 g |
| 19–70+ years | 56 g | 46 g |
Pregnancy and lactation
Stated for reference only. The calculator above is not intended for use during pregnancy or breastfeeding — intake then should be planned with a midwife, doctor or dietitian.
| Stage | RDA | Note |
|---|---|---|
| First trimester | 46 g | Unchanged from the adult female RDA. |
| Second and third trimesters | 71 g | An extra 25 g a day to support fetal growth. |
| Lactation | 71 g | Sustained while breastfeeding. |
What this cannot tell you
A protein target says nothing about the rest of the diet. Protein without enough total energy gets burned for fuel rather than used for repair, so hitting this figure on a severe deficit buys less than it appears to. It also says nothing about what the protein arrives alongside — a target met entirely through processed meat is not equivalent to the same grams from a varied diet, whatever the arithmetic says.
The figures assume healthy kidney and liver function and an adult who is not pregnant. They do not cover recovery from injury or surgery, where requirements rise sharply, and they do not cover chronic kidney disease, where the recommendation runs the other way entirely.
Medical disclaimer. This calculator is for general information and education only. It is not medical advice, not a diagnosis, and not a substitute for professional care. Higher protein intakes need clinical supervision with existing kidney or liver disease. Do not use this to plan intake for a child, during pregnancy or breastfeeding, or alongside an eating disorder.Speak to a doctor or a registered dietitian before making significant dietary changes.Last reviewed .
Frequently asked questions
How much protein do I need per day?
The RDA is 0.8 g per kilogram of bodyweight, which is a floor for avoiding deficiency rather than an optimum. Research on resistance training supports 1.6 to 2.2 g/kg for building or retaining muscle, with little added benefit past about 2.2. A deficit raises the requirement rather than lowering it, because that is when lean mass is most at risk, and older adults benefit from the higher end to counter anabolic resistance.
Why does this ask for body fat percentage?
Because adipose tissue has almost no protein requirement, so multiplying total bodyweight by a fixed figure over-prescribes to anyone carrying a lot of it. At 120 kg and 40% body fat, a plain 1.8 g/kg rule gives 216 g a day, while the same person's 72 kg of lean tissue calls for about 166 g. Leave the field blank and the calculator uses bodyweight, which is fine at an average composition — it is at the extremes that the basis starts to matter.
Does protein timing matter?
Much less than total daily intake, which is the variable that does nearly all the work. The old 30-minute anabolic window has not held up — muscle protein synthesis stays elevated for 24 hours or more after training. What does hold up is a floor per sitting: spreading intake across three to four meals that each clear roughly 0.4 g/kg appears modestly better than taking the same total in one or two.
Can I eat too much protein in one meal?
It will not be wasted in the sense people usually mean — the amino acids are absorbed and used, just more for other purposes and less for building muscle. What does happen is that the synthetic response to a single meal saturates at around 0.4 g/kg, so a 90 g serving does not produce twice the response of a 45 g one. That is an argument for spreading intake out, not for avoiding large meals.
Is high protein intake bad for my kidneys?
In people with healthy kidneys there is no good evidence that high intake causes damage, including in long-term studies of athletes eating well above these figures. Existing chronic kidney disease is an entirely different case, where protein restriction is often advised and should be managed with a clinician rather than a calculator. If you have any diagnosed kidney or liver condition, treat every number on this page as something to discuss rather than follow.
Is plant protein as good as animal protein?
Gram for gram, most plant sources are somewhat less effective, for two reasons: lower digestibility, and amino acid profiles short in one or more essentials — lysine in grains, methionine in legumes. Both are straightforwardly solved. Eating a variety across the day covers the profile without any need to combine sources at the same meal, and adding roughly 10 to 20% to the total compensates for digestibility. Soya and pea isolates score close to animal sources on their own.
How many meals should I split it across?
Three to four for most people. The constraint is that each meal should clear about 0.4 g/kg to fully stimulate synthesis, so the useful number of meals is capped by your total: someone on 120 g at 100 kg can only support three adequate feedings, and splitting into six would leave every one of them submaximal. The calculator shows the ceiling for your own figures.
Do older adults need more protein?
Yes. Anabolic resistance means the same dose of protein produces a smaller synthetic response with age, so both the daily total and the per-meal amount need to be higher to achieve the same effect — often cited as 1.2 to 1.5 g/kg as a baseline for over-65s against the 0.8 g/kg RDA, with per-meal amounts toward 0.4 g/kg rather than below it. Combined with resistance training, this is the main dietary lever against age-related muscle loss.
What about pregnancy and breastfeeding?
Requirements rise, and this calculator is not the right tool for them. The published RDA goes from 46 g a day to 71 g in the second and third trimesters and through lactation, and the table on this page states those figures for reference. Actual intake during pregnancy should be planned with a midwife, doctor or dietitian who knows your circumstances.
Is my data saved or uploaded anywhere?
No. Every calculation runs in your browser. Nothing you type is uploaded, stored, or logged, and the page keeps working offline once loaded. If you share the page URL after calculating, the figures you entered are in the link — clear the query string first if you would rather not pass them on.