How the protein calculator works
The calculator multiplies your bodyweight in pounds by a range that depends on your goal, then rounds to whole grams:
- General health / maintenance: 0.6–0.8 g per lb (about 1.3–1.8 g/kg)
- Active / training regularly: 0.7–1.0 g per lb (about 1.5–2.2 g/kg)
- Building muscle, or cutting while preserving it: 0.8–1.2 g per lb (about 1.8–2.6 g/kg)
Why these ranges are higher than the RDA
The official RDA of 0.8 g/kg (about 0.36 g/lb) is the minimum to prevent deficiency in sedentary adults — not the amount that best supports muscle. A large 2018 meta-analysis of resistance-training studies found gains in muscle mass leveled off around 1.6 g/kg per day, with some people benefiting up to about 2.2 g/kg. Expert groups focused on older adults (the PROT-AGE study group) recommend at least 1.0–1.2 g/kg for healthy people over 65, and more for those who are active, because aging muscle responds less efficiently to each meal’s protein.
The higher end of the “building” range is mainly useful during a calorie deficit, when extra protein helps preserve lean mass.
Worked example and practical tips
A 200 lb man who lifts regularly would get a target of 140–200 g per day. Spread across three or four meals, that’s roughly 35–50 g per meal — a portion of meat or fish about the size of your hand plus a dairy or legume side gets most people there.
If you carry a lot of body fat, basing the target on your goal weight (or lean mass) instead of current weight gives a more realistic number.
Frequently asked questions
How much protein do I need per day to build muscle?
Research on resistance-trained adults suggests about 1.6 g per kg of bodyweight per day (about 0.7 g per lb) captures most of the benefit, with some people benefiting from up to about 2.2 g/kg (1.0 g/lb).
Do older adults need more protein?
Generally yes. Aging muscle responds less to protein, and expert recommendations for older adults are 1.0–1.2 g/kg per day or more, compared with the 0.8 g/kg RDA.
Is a high-protein diet safe for my kidneys?
For people with healthy kidneys, intakes in these ranges have not been shown to cause harm in the research. If you have kidney disease, talk to your doctor before increasing protein.
Should I use my current weight or goal weight?
If you are lean, use current weight. If you have significant fat to lose, using your goal weight gives a more practical target.
Sources
- Morton RW et al. (2018). Protein supplementation and resistance training-induced gains in muscle mass and strength: meta-analysis. Br J Sports Med.
- Jäger R et al. (2017). ISSN Position Stand: protein and exercise. J Int Soc Sports Nutr.
- Bauer J et al. (2013). Optimal dietary protein intake in older people: PROT-AGE position paper. J Am Med Dir Assoc.