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Protein calculator.
How much protein a day, in grams, for your bodyweight and what you are training for. Every figure below is tied to the research it came from, so you can check it rather than take a number on trust.
Where these numbers come from
What protein is for here. Training gives the signal to build; protein supplies the material. In a calorie deficit it does a second job as well: it is the single biggest lever on how much of the weight you lose is fat rather than muscle. That is why the figure below goes up when you are eating less, not down.
The four figures. Body recomposition is highest at 2.2 g per kg of bodyweight, because it is the only goal trying to add tissue while energy is restricted. Losing fat sits at 2 g per kg - high to protect muscle, but not trying to build. Maintaining and building both sit at 1.8 g per kg, the standard strength-training figure, because in a surplus it is the extra energy that does the building and protein does not have to carry it.
Why not more. Morton et al. (2018) pooled 49 randomised trials and 1,863 participants and found the dose-response for gains in lean mass flattening out at about 1.62 g per kg of bodyweight a day, with the confidence interval reaching up to roughly 2.2. Everything on this page sits at or above that plateau. Past it you are not buying more muscle, you are just buying more protein.
Why more when you are dieting. Helms et al. (2014) reviewed protein needs for lean, resistance-trained people in a deficit and recommended 2.3 to 3.1 g per kg of fat-free mass - the leaner you already are and the steeper the deficit, the higher inside that range you should sit. Fat-free mass is the honest denominator here: two people at 90 kg with very different body fat do not need the same protein. Give this calculator your body fat percentage and it will show you that figure too.
What the macro style does. High protein lifts every figure above by roughly 0.2 to 0.4 g per kg and trims fat a little to pay for it. Lower carb lifts protein slightly and fat considerably, which is what actually brings carbohydrate down - carbohydrate takes whatever calories are left in every case. The style never lowers protein.
Timing matters much less than the total. The evidence on spreading protein across the day is far weaker than the evidence on how much of it you eat, and the total is what you should get right first. If you want a rule of thumb anyway, aim for at least 0.4 g per kg of bodyweight in any meal meant to support training, and do not lose sleep over the rest.
On the kidney thing. In people with healthy kidneys, high-protein diets at the intakes discussed here have not been shown to cause kidney damage - the claim comes from advice given to people who already have chronic kidney disease, where protein restriction is genuinely part of treatment. If you have kidney disease, are pregnant, or are managing any condition affected by diet, take the figure on this page to your doctor or dietitian rather than acting on it.
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This is an estimate and a starting point, not medical advice. Every equation of this kind is a population average, so your real burn can sit a few hundred kcal either side of it. Track for two or three weeks and adjust to what actually happens on the scales. If you are pregnant, managing a health condition or unsure, speak to a doctor or dietitian first.
There is no account here and no tracking cookie, so nothing you enter is saved to a profile or tied to you. The sums run on our server, and your answers travel in the page address - which is what makes a result shareable, so treat a link you send as carrying those numbers with it.
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