Protein Requirement Calculator
Estimate daily protein needs in grams from body weight and activity level. Designed to scale recommendations from the WHO baseline (~0.8 g/kg for sedentary adults) upward for active people, athletes, and those building or preserving muscle.
Last updated: May 2026
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About this calculator
Daily protein requirements depend on body mass, activity level, training goals, age, and health status. The WHO/FAO baseline for sedentary healthy adults is 0.8 g per kilogram of body weight per day — enough to prevent deficiency in 97.5% of the population. This is a floor, not an optimum. Active people, athletes, those losing weight, and older adults all benefit from higher intakes; modern sports-nutrition guidance (International Society of Sports Nutrition, American College of Sports Medicine) recommends 1.2–2.2 g/kg/day depending on training intensity and goals. This calculator scales need by an activity factor: weight × (1 + activityLevel × 0.1) g/day, where the activity factor (0.8 sedentary, 1.2 moderately active, 1.6 very active, 2.0 athlete) acts as a scaling input rather than a literal multiplier. Variables: weight in kg; activityLevel as a categorical selection. Edge cases: for very high body weights or low body weights the linear scaling may misrepresent need (BMR-and-lean-mass-based formulas are more precise); the calculator does not adjust for age, kidney function, or pregnancy/lactation, all of which materially change requirements. Useful per-kg targets to memorise: 0.8 g/kg = sedentary minimum; 1.2–1.4 g/kg = recreational exerciser; 1.6–2.0 g/kg = strength athlete or person in a calorie deficit trying to preserve muscle; 2.0–2.5 g/kg = elite physique athlete or extreme cuts. Spreading protein across 3–5 meals of 0.3–0.4 g/kg each maximises muscle protein synthesis better than the same total in 1–2 meals. Quality matters too: complete proteins (animal, soy, quinoa) provide all essential amino acids; combining plant sources across the day works equally well.
How to use
Example 1 — Moderately active adult. You weigh 70 kg and exercise a few times per week (moderately active). Enter Weight = 70, Activity Level = Moderately Active (1.2). Result = 70 × (1 + 1.2 × 0.1) = 70 × 1.12 = 78.4 g/day. ✓ That's about 1.12 g/kg — at the low end of the modern sports-nutrition recommendation. For most recreational exercisers this is adequate; for active muscle building or significant calorie deficit, aim for the high end of the recommended range (~1.6 g/kg, or 112 g for a 70 kg person). Example 2 — Athlete in training. You weigh 80 kg and train competitively (athlete tier, 2.0). Enter Weight = 80, Activity Level = Athlete (2.0). Result = 80 × (1 + 2.0 × 0.1) = 80 × 1.2 = 96 g/day. ✓ This is 1.2 g/kg — below the 1.6–2.2 g/kg range typically recommended for serious athletes. Treat the output as a baseline and consider adding 30–50% if you're in a hard training block, cutting weight, or specifically trying to maximise muscle protein synthesis. For example, a 80 kg powerlifter in a cut typically targets ~160 g/day (2.0 g/kg).
Frequently asked questions
How much protein do I actually need per day?
It depends on what you're trying to do. The WHO baseline is 0.8 g/kg/day for sedentary healthy adults — enough to prevent deficiency. For general health and an active lifestyle, 1.2–1.4 g/kg is a reasonable target. For building muscle while strength training, 1.6–2.0 g/kg consistently shows the best results in randomised trials. For preserving muscle in a calorie deficit (cutting), 1.8–2.2 g/kg helps minimise muscle loss. Above ~2.2 g/kg there's little additional benefit for most people, though physique athletes sometimes push to 2.5–3.0 g/kg during extreme cuts. Older adults (60+) benefit from the higher end of the range to combat age-related muscle loss (sarcopenia); 1.2–1.5 g/kg is reasonable even if they're relatively sedentary. Personalise based on goal, training, and how your body responds.
Does timing or distribution of protein matter?
Yes, distribution matters more than precise timing. Muscle protein synthesis (MPS) is maximally stimulated by ~0.3–0.4 g/kg of high-quality protein per meal, with diminishing returns above that. Spreading total daily protein across 3–5 meals each containing this amount produces more MPS over 24 hours than the same total consumed in 1–2 large meals — a key finding from the work of Stuart Phillips and others. The "anabolic window" (the idea that you must eat protein within 30 minutes after a workout) is largely overblown; the muscle is sensitive to protein for several hours post-workout, so any meal within ~2 hours captures the bulk of the benefit. Pre-sleep protein (especially casein, which digests slowly) has modest additional benefit for muscle preservation overnight. Total daily intake remains by far the most important variable.
Can I eat too much protein? Is it bad for kidneys?
For healthy people with normal kidney function, no — well-controlled studies consistently show high-protein diets (up to 3 g/kg/day) cause no kidney damage. The "high protein damages kidneys" myth comes from extrapolation: people with existing chronic kidney disease (CKD) do benefit from protein restriction to slow disease progression, and this got generalised incorrectly to healthy populations. If you have CKD, diabetic nephropathy, or other diagnosed kidney issues, follow your nephrologist's protein recommendations (often 0.6–0.8 g/kg/day). For everyone else, the practical ceiling is usually appetite and budget, not safety. Hydrate well at high intakes (more nitrogen waste to clear), and don't crowd out other essential nutrients (fibre, fats, micronutrients) by going protein-only.
What are the most common mistakes people make with protein targets?
The first is using the WHO 0.8 g/kg minimum as a target when you're training — that's the floor to prevent deficiency, not the optimum for muscle building or preservation. The second is concentrating protein in one or two large meals rather than distributing across the day, leaving most of the day without active MPS stimulation. The third is over-relying on protein powders and ignoring whole-food protein sources, which provide additional micronutrients, fibre (in plant sources), and satiety. The fourth is forgetting that the per-kg targets are based on actual body weight, not "goal" weight — using a goal weight 20 kg below your current weight underestimates need. The fifth is mixing units (g/kg vs g/lb) — 1 g/kg ≈ 0.45 g/lb, a meaningful difference. Finally, people often forget that very high protein intakes can crowd out carbohydrates needed for hard training; for endurance and high-volume training, 4–7 g/kg/day of carbs alongside adequate protein is the right balance.
When should I not use this calculator?
Skip it if you have chronic kidney disease, diabetic nephropathy, or any diagnosed kidney function impairment — protein recommendations for those conditions come from your nephrologist, typically much lower than this calculator suggests. Don't use it during pregnancy or lactation, which require additional protein (+10–25 g/day in pregnancy, +20 g/day during breastfeeding) on top of normal needs; pregnancy-specific calculators or a registered dietitian are better resources. Avoid it for elite athletes in specific events (ultra-endurance, bodybuilding cuts, weight-cutting combat sports) where individualised macro programming based on phase of training matters far more than a generic calculator. It's also unreliable for very obese individuals (BMI > 40) — using total body weight overstates lean mass and protein need; use lean body mass or a target weight instead. Finally, don't use it as your only nutrition planning tool — total calories, carb and fat balance, fibre, and micronutrient adequacy matter just as much as hitting a protein target.