Protein Calculator: how much protein do I need a day?

Work out how many grams of protein you need a day from your body weight, with the official minimum, the US Dietary Guidelines, and the ranges for adults over 65, athletes and strength training.

Protein for 70 kg by guideline
Who it's for	g per kg	A day
Adult minimum (RDA)US National Academies, 2005	0.8	56 g
Adult, healthy eatingDietary Guidelines for Americans 2025–2030	1.2–1.6	84–112 g
Adult over 65ESPEN expert group, 2014	1.0–1.2	70–84 g
Athlete or regular trainingACSM, Academy of Nutrition and Dietetics, Dietitians of Canada, 2016	1.2–2.0	84–140 g
Strength training to build muscleInternational Society of Sports Nutrition, 2017	1.4–2.0	98–140 g
Losing fat while strength trainingInternational Society of Sports Nutrition, 2017	2.3–3.1	161–217 g

How the protein calculator works

Protein advice is given in grams per kilogram of body weight per day, so the calculator multiplies your weight by the range for the group you choose: grams a day = g per kg × your weight in kg. If you enter pounds, it converts them first (1 lb = 0.4536 kg). The per-meal figure is the daily amount divided by your meals.

Worked example

Someone who weighs 70 kg (154 lb) and lifts weights to build muscle: 1.4 × 70 = 98 g and 2.0 × 70 = 140 g, so 98–140 g of protein a day. Over 4 meals that's 25–35 g a meal. The minimum for the same person (the RDA, 0.8 g per kg) would be 56 g.

Which range should I use?

Adult minimum (RDA), 0.8 g/kg: the amount that meets the needs of nearly all healthy adults, set by the US National Academies. It's a floor, not a target.
Adult, healthy eating, 1.2–1.6 g/kg: the Dietary Guidelines for Americans 2025–2030.
Over 65, 1.0–1.2 g/kg: at least this much, from the ESPEN expert group, to help keep muscle strength with age.
Athletes, 1.2–2.0 g/kg: the 2016 joint position of the American College of Sports Medicine, the Academy of Nutrition and Dietetics and Dietitians of Canada.
Strength training, 1.4–2.0 g/kg, and losing fat while strength training, 2.3–3.1 g/kg: the International Society of Sports Nutrition's 2017 position stand.

Tips

Fit your protein into your calories with the macro calculator; if you're losing weight, start with the calorie deficit calculator.
Food first: meat, fish, eggs, dairy, beans, lentils, tofu and nuts all count towards the total.
Recalculate as your weight changes; the ranges are per kg of body weight.

Sources, checked 2 October 2026: US National Academies, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005); MedlinePlus on the Dietary Guidelines for Americans 2025–2030; Deutz NEP et al., ESPEN expert group recommendations on protein intake with aging, Clinical Nutrition 2014;33:929–36; Thomas DT, Erdman KA, Burke LM, Nutrition and Athletic Performance (2016); Jäger R et al., ISSN position stand: protein and exercise, J Int Soc Sports Nutr 2017;14:20. Not medical advice.

Frequently asked questions

How much protein do I need a day?

The official minimum for healthy adults (the RDA) is 0.8 g per kg of body weight, about 56 g for someone weighing 70 kg (154 lb). The Dietary Guidelines for Americans 2025–2030 suggest more: 1.2–1.6 g per kg. People who train regularly need more again, up to about 2 g per kg.

How much protein do I need to build muscle?

The International Society of Sports Nutrition says 1.4–2.0 g of protein per kg of body weight a day is enough for most people who exercise, together with resistance training. The joint position of the American College of Sports Medicine and US and Canadian dietitians gives 1.2–2.0 g per kg for athletes.

Should I eat more protein while losing weight?

If you strength train, eating less can cost you muscle, and the International Society of Sports Nutrition says resistance-trained people may need 2.3–3.1 g per kg during a calorie deficit to keep it. For everyone else, the 1.2–1.6 g per kg in the US guidelines is a sensible target while you diet.

Do older adults need more protein?

An ESPEN expert group recommends at least 1.0–1.2 g per kg a day for healthy people over 65, and 1.2–1.5 g per kg for older people with an acute or chronic illness, together with daily physical activity. Ask a doctor if you have kidney disease.

How do I turn grams per kg into grams per pound?

Multiply by 0.4536 (or divide by 2.2046). So 0.8 g per kg is 0.36 g per lb, 1.6 g per kg is 0.73 g per lb and 2.0 g per kg is 0.91 g per lb. Switch the calculator to pounds and it does this for you.

Is it better to eat protein in one go or spread it out?

Spread it out. The International Society of Sports Nutrition suggests about 0.25 g per kg of body weight, or 20 to 40 g, per meal, eaten every 3 to 4 hours across the day.