| Body weight | Building muscle | Losing fat, keeping muscle | Holding steady |
|---|---|---|---|
| 140 lb (63.5 kg) | 98–140 g | 140–168 g | 112–140 g |
| 160 lb (72.6 kg) | 112–160 g | 160–192 g | 128–160 g |
| 180 lb (81.6 kg) | 126–180 g | 180–216 g | 144–180 g |
| 200 lb (90.7 kg) | 140–200 g | 200–240 g | 160–200 g |
| 220 lb (99.8 kg) | 154–220 g | 220–264 g | 176–220 g |
Protein is argued about more than almost anything else in fitness, and most of the arguing concerns a spread of about thirty grams. This calculator puts your own body weight into the ranges the evidence actually supports, so you can stop guessing and get on with eating.
How to use it
Enter your body weight, pick the goal that matches what you are doing right now, and the calculator returns a daily range in grams. If you weigh yourself in kilos, switch the unit — the number converts rather than resetting, so 180 lb becomes 81.6 kg and the answer stays the same.
Where these numbers come from
The ranges here are the ones this site already publishes, not a second set invented for a calculator. Building muscle runs from 0.7 to 1.0 grams per pound of body weight. That ceiling is not arbitrary: a 2018 meta-analysis in the British Journal of Sports Medicine found muscle growth plateaus at roughly 1.6 g/kg, which is where the top of the range sits. How much protein you actually need to build muscle works through those studies in detail, including why the floor is higher than most people assume.
Losing fat while holding on to muscle pushes the target up to 1.2 g/lb. When you are eating less than you burn, a larger share of your intake goes to defending existing tissue instead of fuelling new growth, so the requirement rises rather than falls. This is the opposite of what most diets assume.
Splitting it across the day
A daily total is only useful if you can actually eat it. Divide the figure across your meals, and aim for 25 to 40 grams per sitting, which is the window that reliably stimulates muscle protein synthesis. A 180 lb man building muscle lands on 126 to 180 g a day: four meals of roughly 30 to 45 g, or three larger ones if you prefer fewer sittings.
If your target splits into portions below 25 g, the problem is usually the meal count rather than the total. Fewer, bigger meals will serve you better than four small ones, and whether protein timing actually matters covers how much the distribution really moves the outcome.
When to aim higher
Two situations push you toward the top of your range. A calorie deficit is one, for the reason above. Being over forty is the other: muscle protein synthesis responds less strongly to the same dose as you age, so protein powder for men over 40 recommends 0.8 to 1.0 g per pound for anyone training three or four times a week.
Worth noticing: the second situation is not a reason to multiply the first. The ranges already account for the age effect, which is why the calculator asks for your weight and your goal rather than applying a percentage on top. Adding both would land you on numbers this site does not support.
Two things people get wrong
One gram per pound is a habit, not a finding. It is a convenient way to remember the top of the muscle-building range and it is perfectly safe, but the evidence does not put the floor anywhere near it. Treating it as the entry price leads people to eat far more than they need, or to give up because the target looks unreachable.
The kidney worry does not survive contact with the literature for healthy people. Intakes up to 3.3 g/kg — well above anything this calculator returns — have shown no effect on kidney function in people without existing disease. If you do have kidney disease, this is a conversation for your doctor rather than a web page.
What the number does not cover
It does not tell you about protein quality, and it does not tell you whether you are eating enough total calories, which matters more for how you look than the protein figure does. It also will not tell you what to eat. For that, the highest-protein foods, ranked lists what actually moves the number without reaching for a shake.
Treat the output as a target to aim at rather than a threshold to clear. Hitting it most days is what matters; missing it on a Tuesday is not a problem.