Protein Intake Calculator.

The U.S. RDA of 0.8 g/kg is set at the lower bound for nitrogen balance in sedentary adults. It is not the optimum for muscle protein synthesis, body composition, or healthy aging. A growing literature on resistance-trained adults and older adults converges on 1.6–2.2 g/kg of body weight per day for muscle gain or preservation during a fat loss phase.

This calculator multiplies your body weight by an activity-and-goal-specific coefficient drawn from that range. Sedentary maintenance sits around 0.8 g/kg; building muscle while training hard pushes the multiplier toward 2.0–2.2 g/kg. Above ~2.4 g/kg there is no additional benefit for muscle protein synthesis in healthy adults.

The number is a daily target, not a per-meal cap. The site shows your number split across 3 and 4 meals — that 25–45 g per-meal range is where most adults maximize the muscle protein synthesis response to a single feeding.

Distribute the total across the day rather than back-loading into dinner. Several studies show that an even distribution of 0.4 g/kg per meal across 3–4 meals produces a larger 24-hour anabolic response than skewed intake (e.g. 10 g breakfast, 80 g dinner).

Most adults under-hit their target by 30–50 g not because of willpower but because every snack window defaults to carbs. The fix is mechanical: anchor each meal with a 30 g+ protein source first, then build the rest of the plate around it.

High-density anchors: chicken breast (31 g per 100 g cooked), Greek yogurt (10 g per 100 g, 17 g in a 170 g cup), cottage cheese (11 g per 100 g), eggs (6 g each), whey isolate (24 g per scoop), lentils (9 g per 100 g cooked), tofu (8 g per 100 g), tinned tuna (25 g per 100 g).

Three cases the simple multiplier under- or over-estimates. (1) Significant excess body fat: scale the multiplier off lean body mass or a target weight rather than current weight, otherwise you over-shoot. (2) Chronic kidney disease, certain liver conditions, or any prescribed protein restriction: follow your clinician — the calculator does not know your renal function. (3) Adults over 65 who are sarcopenic or recovering from illness: the literature supports the upper end of the range (1.2–1.6 g/kg even at maintenance) to offset anabolic resistance.