Protein Calculator

It depends on body weight and activity. The Institute of Medicine RDA is 0.8 g/kg/day for sedentary adults — that is the minimum needed to prevent deficiency, not the optimum. The American College of Sports Medicine, Academy of Nutrition and Dietetics and Dietitians of Canada jointly recommend 1.2-2.0 g/kg/day for athletes (2016 joint position). The International Society of Sports Nutrition's 2017 position stand recommends 1.4-2.0 g/kg/day for most exercising adults and up to ~2.3 g/kg during a calorie-restricted cut to preserve lean mass.

The Recommended Dietary Allowance is 0.8 g/kg/day for adults, set by the Institute of Medicine in 2005 from nitrogen-balance studies. It is designed to cover the daily needs of 97.5 % of healthy adults and prevent deficiency. It is not designed to optimise muscle protein synthesis, support resistance-training adaptations, or preserve lean mass during weight loss. Sport-nutrition bodies (ACSM, ISSN) recommend higher intakes — 1.2-2.2 g/kg/day — because additional protein supports muscle protein synthesis, recovery, and satiety, and there is no evidence of harm to kidney function in healthy adults at these intakes.

Either — the calculator converts pounds to kilograms internally using the NIST exact conversion 1 lb = 0.45359237 kg. The underlying gram-per-kilogram recommendations are universal across both unit systems. If you live in a country that uses pounds (US) just select "Pounds (lb)"; if you use kilograms (UK, EU, most of the world), select "Kilograms (kg)". The output is always grams of protein per day because food labels are in grams.

Not in healthy adults. The "high protein damages the kidneys" claim originates in studies of people with pre-existing chronic kidney disease, where reducing protein can slow disease progression. Systematic reviews in healthy adults (Devries et al. 2018, J Nutr; Antonio et al. 2014-16 trials in trained athletes up to 4.4 g/kg/day) show no adverse effect on kidney function markers in the short to medium term. The ISSN 2017 position stand explicitly states that high-protein diets are safe in healthy individuals. If you have known kidney disease or are at risk, follow your nephrologist's guidance rather than a general calculator.

It is the Atwater general factor for protein — the average physiological fuel value, standardised by the USDA and adopted by the FAO since the early 20th century. Protein (4 kcal/g) and carbohydrate (4 kcal/g) are similar because their hydrocarbon skeletons are at similar oxidation states; fat (9 kcal/g) is much denser because its chains are more chemically reduced. The 4 kcal/g figure appears on every food label in the world. More precise food-specific Atwater factors exist for individual foods but 4 kcal/g is the universal standard for calculators of this kind.

Yes — protein should go up, not down. When you eat below maintenance calories, the body breaks down both fat and lean tissue for energy. A higher protein intake (typically 1.8-2.4 g/kg/day, or up to 2.3-3.1 g/kg of fat-free mass per Helms et al. 2014) reduces lean-mass loss during the cut. The "Calorie-restricted cut (2.0 g/kg)" preset sits at the upper bound of the ACSM/AND/DC 2016 athlete range; the "Maximum sport-nutrition target (2.2 g/kg)" preset adds extra headroom for trained individuals in an aggressive deficit.

For total grams, no — both count toward the target. For protein quality, slightly. Animal proteins (meat, fish, eggs, dairy) and isolated soy are "complete" — all nine essential amino acids in adequate proportions. Most individual plant proteins are limiting in at least one essential amino acid (cereals in lysine; legumes in methionine), but a varied plant diet across the day easily covers all essential amino acids. Plant-based eaters are often advised to aim toward the upper end of the protein range and ensure variety across legumes, grains, nuts, seeds and soy. Leucine content matters specifically for muscle protein synthesis; whey and soy isolate are highest, with most other plant sources slightly lower per gram.

All sources count toward the target. Food labels report total protein per serving, which already includes everything. Bread, oats, rice, pasta, nuts, dairy, vegetables and pulses all contribute meaningful protein and are added to the obvious sources (meat, fish, eggs, tofu, whey). Tracking only "high-protein" foods systematically underestimates intake by 20-40 % for most diets. If you use a food-tracking app, the protein total at the end of the day is what matters relative to this calculator's target.