How your protein target is calculated
The calculator picks a range in grams per kilogram that reflects published recommendations for your situation, then multiplies it by a basis weight: your body weight if you're lean or average, or an adjusted weight when body fat is high (lean mass divided by 0.8 for men, 0.72 for women, which is your weight at roughly 20%/28% body fat).
- Building muscle: 1.6–2.2 g/kg (Morton 2018; ISSN 2017).
- Losing fat while lifting: 1.8–2.7 g/kg, higher when lean, to help retain muscle in a deficit (Helms 2014).
- Maintenance: 1.4–2.0 g/kg; endurance athletes 1.2–1.6 g/kg; no structured training 1.0–1.2 g/kg.
- Age 50+: range raised slightly, as older muscle appears less responsive to smaller protein doses.
- Vegan: +10% to offset lower digestibility and leucine content of some plant proteins.
Per meal
Spreading protein across 3–6 meals of roughly 0.4–0.55 g/kg each is a practical way to reach your target while repeatedly stimulating muscle protein synthesis. A serving with about 2.5–3 g of leucine (e.g. 25–40 g of most animal proteins) is commonly cited as enough to maximize the response in younger adults.
Frequently asked questions
How much protein do I need to build muscle?
A widely cited 2018 meta-analysis (Morton et al.) found that the benefit of protein intake on resistance-training gains plateaued at about 1.6 g per kg of body weight per day on average, with the upper confidence limit around 2.2 g/kg. The ISSN position stand recommends 1.4–2.0 g/kg/day for most exercising people.
Is too much protein bad for your kidneys?
In healthy adults, studies of high-protein diets have not shown harm to kidney function at intakes common among athletes. People with existing kidney disease are a different case and should follow their doctor's guidance.
How much protein can the body absorb per meal?
Your body absorbs virtually all the protein you eat. The open question is how much of it goes to muscle building in one sitting. A practical strategy from Schoenfeld and Aragon (2018) is about 0.4 g/kg per meal over at least four meals, up to 0.55 g/kg at the upper end.
Should I calculate protein from total weight or lean mass?
For lean or average-weight people, total body weight works. For people with higher body fat, basing protein on goal weight or lean body mass avoids needlessly high targets. This calculator does that automatically when you enter body fat above about 25% (men) or 32% (women).
Do vegans need more protein?
Plant proteins tend to be slightly less digestible and lower in leucine, so some researchers suggest aiming for the upper end of recommendations or combining sources (legumes + grains, soy). The calculator adds about 10% when you choose a fully plant-based diet.
Sources & further reading
- Morton RW, Murphy KT, McKellar SR, et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults . Br J Sports Med 52(6):376–384 · doi:10.1136/bjsports-2017-097608
- Jäger R, Kerksick CM, Campbell BI, et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise . J Int Soc Sports Nutr 14:20 · doi:10.1186/s12970-017-0177-8
- Schoenfeld BJ, Aragon AA (2018). How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution . J Int Soc Sports Nutr 15:10 · doi:10.1186/s12970-018-0215-1
- Helms ER, Aragon AA, Fitschen PJ (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation . J Int Soc Sports Nutr 11:20 · doi:10.1186/1550-2783-11-20