Protein Calculator
How much protein a day, as a range, with the reasoning shown.
Most active adults need 1.2 to 1.6 g of protein per kg of body weight a day, rising to 1.6 to 2.2 g/kg for building muscle and 1.6 to 2.0 g/kg when losing fat while preserving muscle. An 80 kg person building muscle lands around 128 to 176 g a day. The RDA of 0.8 g/kg is a deficiency floor, not a target.
This calculator is for general education only and is not medical or dietetic advice. The ranges come from research on healthy adults and do not apply to children, to pregnancy or breastfeeding, or to anyone with kidney or liver disease, where protein is often deliberately restricted and a higher intake can be harmful. If you have a health condition, are pregnant, or are under 18, please speak to a doctor or a registered dietitian before changing your protein intake.
Daily protein range, based on body weight
Midpoint 98 g. The range is the answer. The midpoint is just its middle, not a target to hit exactly.
Whole grams, rounded. Estimates for healthy adults. See the notes below.
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About the Protein Calculator
Protein recommendations are given per kilogram of body weight, and they vary by what you are trying to do. The RDA of 0.8 g/kg is the figure most often quoted, and it is widely misunderstood: it is the amount that prevents deficiency in most healthy adults, which is a floor rather than a target, and the nitrogen balance method it was derived from has been criticized for understating real requirements. Indicator amino acid work by Humayun and colleagues puts a population-safe intake nearer 1.2 g/kg. The RDA itself was fixed in the 2005 Dietary Reference Intakes report and has not been reset, but federal dietary guidance and sports nutrition guidance have both moved above it, so treat 0.8 as the floor it was always meant to be rather than as a current target. Current federal guidance now puts the range for adults generally, not only for people who train, at roughly where the sports nutrition figures below sit. For an adult who trains, mainstream sports nutrition guidance sits at 1.2 to 1.6 g/kg. For building muscle the meta-analytic evidence points to benefits leveling off around 1.6 g/kg with an upper bound near 2.2. When you are eating in a deficit, higher intakes help protect lean mass, which is why the fat loss range starts at the top of the general range. This tool gives you a range rather than a single number, because the underlying evidence is a range and a single figure would be false precision. A caveat about basing this on total body weight: the research behind the higher figures was mostly done in lean, trained people, and it is expressed per kilogram of fat-free mass. Applying a fat-free-mass number to total body weight applies it to fat mass too, which overshoots for anyone carrying a lot of it. If you know your body fat percentage, enter it and the tool adds a second range built on lean mass, 1.6 to 2.7 g per kg of it. That band is the same whichever goal you pick, so read it as a sanity check rather than a goal-specific answer. At high body fat it comes out lower than the bodyweight figure, which is the point. At low or moderate body fat it can come out higher, and there the bodyweight figure is the safer one to work from. The tool shows both rather than quietly picking one for you.
Frequently asked questions
How much protein do I need per day?+
It depends on your goal. Roughly 1.2 to 1.6 g per kg of body weight for a generally active adult, 1.6 to 2.2 for building muscle, and 1.6 to 2.0 when losing fat and trying to keep muscle. The RDA of 0.8 g/kg is a deficiency floor rather than a recommendation to aim at.
Should I calculate protein on body weight or lean mass?+
Neither is always right. The lean-mass band is a fixed 1.6 to 2.7 g per kg of lean mass whichever goal you pick, so it is a sanity check rather than a goal-specific answer. At high body fat it comes out lower than the bodyweight figure, and that is where it earns its place, because fat tissue does not carry the same protein requirement as muscle. At low or moderate body fat it can come out higher, and there the bodyweight figure is the safer one to work from. This tool shows both when you supply a body fat figure, so you can see the difference rather than take one on trust.
Can you eat too much protein?+
In healthy adults with normal kidney function, the trials done so far have not found harm from higher intakes, though most of them are short. There is no added benefit either, and it displaces other food. Kidney disease is the case that matters: people with reduced kidney function are often advised to restrict protein, in current KDOQI guidance to around 0.55 to 0.8 g/kg, which is the opposite of what this tool will tell you. Maintenance dialysis runs the other way again, at roughly 1.0 to 1.2 g/kg. If that applies to you, follow your clinician, not a calculator.
Does protein need to be spread across the day?+
It helps a little and it is not the main thing. Spreading intake across three or four meals with a reasonable amount in each supports muscle protein synthesis better than one large serving, but the total across the day matters far more than the distribution. The per meal figure here is a convenience, not a rule.
Do these numbers apply to everyone?+
No. Every range here is derived from research on healthy adults. Older adults generally need more to counter age related muscle loss, pregnancy and breastfeeding raise requirements, and children and teenagers are assessed differently altogether. Anyone with kidney or liver disease should be guided by their clinician.
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