Protein Calculator — How Much Protein Do I Need Per Day?

How this is calculated

Daily range = reference weight × g/kg for your goal
Target = midpoint of the range
Per meal ≈ 0.4 g/kg × reference weight

Ranges (g per kg)

Sedentary / general health        0.8–1.0
Active / recreational exercise    1.2–1.6
Building muscle                   1.6–2.2
Fat loss, preserving muscle       1.8–2.4
Older adult (65+), minimum        1.0–1.2

High body fat (above 30% men / 40% women)

Lean mass = weight × (1 − body fat % ÷ 100)
Reference weight = lean mass × 1.25

Otherwise the reference weight is your body weight. The per-kg ranges were set for people of typical body composition; scaling lean mass by 1.25 keeps targets realistic for people carrying a lot of body fat instead of overestimating them.

Sources

Jäger R et al. (2017), International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr 14:20.
Bauer J et al. (2013), Evidence-based recommendations for optimal dietary protein intake in older people (PROT-AGE). J Am Med Dir Assoc 14:542–559.
Institute of Medicine (2005), Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids.

Why protein matters

Protein supplies the amino acids your body uses to build and repair muscle, make enzymes and hormones, and support your immune system. It's also the most filling macronutrient, which helps when you're eating less to lose weight.

How much you need

The recommended dietary allowance of 0.8 g per kg is the minimum to prevent deficiency in sedentary adults—not an optimum. The International Society of Sports Nutrition recommends 1.4–2.0 g/kg for most exercising people, and research on muscle gain points to benefits up to about 1.6–2.2 g/kg. During fat loss, higher intakes of up to 2.4 g/kg help protect muscle. Adults over 65 need more than younger adults to maintain muscle, at least 1.0–1.2 g/kg.

If you have a lot of body fat, using total weight overestimates your needs, so the calculator switches to lean mass above 30% body fat for men and 40% for women.

Spreading it across the day

Muscle responds best to protein spread over several meals rather than one large serving. Around 0.4 g/kg per meal, across three to five meals, is a practical target. For an 80 kg person that's about 32 g per meal.

Vegetarian protein

Vegetarians can meet these targets comfortably by combining dairy, eggs (if eaten), legumes, soy and grains across the day. Dal with rice, paneer, tofu, soya chunks, Greek yogurt and milk are all good sources. A protein powder can fill gaps on busy days.

Frequently asked questions

How much protein do I need to build muscle?

Most research supports 1.6–2.2 g per kg of body weight a day, combined with resistance training. Spread it across three to five meals of roughly 0.4 g/kg each.

Can you eat too much protein?

For healthy adults, intakes up to about 2.4 g/kg appear safe. If you have kidney disease or reduced kidney function, follow your doctor's advice on protein.

Can vegetarians get enough protein?

Yes. Combining dairy, legumes, soy, whole grains and, if you eat them, eggs across the day covers even high targets. Soya chunks, paneer and Greek yogurt are especially protein-dense.

Why does the calculator use lean mass for some people?

Protein needs track muscle and organs more than fat. Above 30% body fat (men) or 40% (women), basing the target on total weight would overestimate it, so the calculator uses lean mass × 1.25 instead.