Protein Calculator: How Many Grams of Protein You Need Per Day
A protein calculator multiplies your body weight in kilograms by a grams-per-kilogram figure. The adult RDA is 0.8 g/kg per day, which is 64 g for an 80 kg person.[1] Position papers advise 1.4 to 2.0 g/kg for people who exercise regularly, which is 112 to 160 g at 80 kg, and at least 1.0 to 1.2 g/kg for adults over 65.[2][3] Pick a profile below to see the range.
Protein calculator
Estimate from published ranges, not a prescription. The RDA is a minimum; ask your clinician or a registered dietitian what fits you.
How much protein do you need per day?
For most adults the RDA is 0.8 g/kg of body weight per day, and higher ranges apply to people who exercise or are over 65. The RDA is a figure set in the National Academies 2005 report on dietary reference intakes.[4][1] For an 80 kg adult that is 64 g a day. The International Society of Sports Nutrition advises 1.4 to 2.0 g/kg for most exercising people, which is 112 to 160 g at 80 kg.[2] A study group on aging, PROT-AGE, advises adults over 65 to average at least 1.0 to 1.2 g/kg, which is 80 to 96 g at 80 kg.[3] Published guidance is written in grams of protein per kilogram of body weight per day, so the same 80 kg adult can see a spread of 64 to 160 g between the lowest and highest profiles below. The calculator prints a range for the profile you pick, plus the RDA line for comparison.
| Body weight | RDA at 0.8 g/kg | Over 65, 1.0 to 1.2 g/kg | Exercising, 1.4 to 2.0 g/kg |
|---|---|---|---|
| 50 kg (110 lb) | 40 g | 50 to 60 g | 70 to 100 g |
| 60 kg (132 lb) | 48 g | 60 to 72 g | 84 to 120 g |
| 70 kg (154 lb) | 56 g | 70 to 84 g | 98 to 140 g |
| 80 kg (176 lb) | 64 g | 80 to 96 g | 112 to 160 g |
| 90 kg (198 lb) | 72 g | 90 to 108 g | 126 to 180 g |
| 100 kg (220 lb) | 80 g | 100 to 120 g | 140 to 200 g |
| 110 kg (243 lb) | 88 g | 110 to 132 g | 154 to 220 g |
How do you calculate protein from body weight?
Convert your weight to kilograms, then multiply by a grams-per-kilogram figure. If you know your weight in pounds, divide by 2.2046 first, because one kilogram is about 2.2 pounds. A person who weighs 180 lb is 81.65 kg. At the RDA of 0.8 g/kg that is 65 g a day.[1] At the 1.4 to 2.0 g/kg range the International Society of Sports Nutrition gives for most exercising people, the same person gets 114 to 163 g a day.[2] The calculator rounds each result to the nearest whole gram and prints both ends of the range. It also splits the daily total over three or four meals. For example, 112 to 160 g a day is about 37 to 53 g per meal across three meals, or 28 to 40 g across four. For a 100 kg person the 140 to 200 g exercising range is 47 to 67 g per meal across three meals. Those splits are plain division, not a feeding schedule.
Is the RDA of 0.8 g/kg enough?
It is the baseline for adults in general, and higher ranges are advised for some groups. The International Society of Sports Nutrition says 1.4 to 2.0 g/kg is sufficient for most exercising people, which is well above the RDA.[2] The PROT-AGE group says older adults need more protein than younger adults, citing age-related changes in how the body handles it, and advises at least 1.0 to 1.2 g/kg after age 65.[3] A 2025 joint advisory from four nutrition and obesity societies also notes that the RDA is under review by the National Academies, so the 0.8 figure may change.[1] The same advisory says 1.2 to 1.6 g/kg per day has been proposed during active weight reduction, which at 80 kg is 96 to 128 g against 64 g at the RDA.[1] Ask a clinician or a registered dietitian which number fits your health and goals.
How much protein do you need if you exercise?
An overall daily intake of 1.4 to 2.0 g/kg is sufficient for most exercising individuals, to build muscle and to maintain it, according to the International Society of Sports Nutrition position stand on protein and exercise.[2] For a 70 kg person that is 98 to 140 g a day, and for a 90 kg person it is 126 to 180 g. The same position stand says that protein doses of 20 to 40 g per serving, or 0.25 g/kg, are a general recommendation for maximizing muscle protein synthesis, and that doses should ideally be spread every 3 to 4 hours across the day.[2] It also says that intakes of 2.3 to 3.1 g/kg may be needed to retain lean mass in resistance-trained people during hypocaloric periods.[2] That higher range is a specialist case and the calculator does not use it. At 70 kg it would be 161 to 217 g, well above the 98 to 140 g that the exercising profile prints.
How much protein do adults over 65 need?
The PROT-AGE Study Group, an international group of geriatric and nutrition researchers, recommends that adults over 65 average at least 1.0 to 1.2 g of protein per kilogram of body weight per day to maintain and regain lean body mass and function.[3] Its paper advises 1.2 g/kg or more for older adults who exercise and are otherwise active, and 1.2 to 1.5 g/kg for most older adults who have an acute or chronic disease.[3] For a 70 kg person those figures are 70 to 84 g, at least 84 g, and 84 to 105 g. The paper names one exception: people with severe kidney disease, with an estimated GFR below 30 mL/min/1.73 m2 who are not on dialysis, may need to limit protein.[3] The calculator has an over 65 profile and an over 65 with illness or recovery profile, and neither replaces advice from a clinician who knows your health.
Can you eat too much protein?
For exercising adults the published range stops at 2.0 g/kg per day, and some people are told to eat less protein than that. The sports nutrition position stand reports that 1.4 to 2.0 g/kg is sufficient for most exercising individuals.[2] The 2025 joint advisory on nutrition during GLP-1 therapy, which covers medicines such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound), says to avoid prolonged intakes at or above 2 g/kg per day in that setting, which is 160 g or more at 80 kg.[1][5][6][7][8] The clearest exception comes from kidney health. The PROT-AGE paper says older adults with severe kidney disease who are not on dialysis may need to limit protein.[3] People with kidney disease, and anyone told to limit protein or fluids, should follow their clinician instead of any calculator. At 80 kg the RDA gives 64 g and the 2.0 g/kg line gives 160 g, so the spread between them is 96 g.
Should protein be based on current weight or goal weight?
Published guidance does not settle which weight to use for every person. The 2025 joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society says it is unclear whether protein should be based on actual weight, adjusted or ideal weight, or fat-free mass, and that actual weight can overestimate needs in people with obesity.[1] For a 100 kg person, the difference is large. At 1.2 g/kg, actual weight gives 120 g, while a reference weight of 80 kg gives 96 g. At 1.6 g/kg the same two weights give 160 g and 128 g. The calculator uses the weight you enter and does not choose for you. If your clinician or dietitian gives you a reference weight, enter that one. The GLP-1 protein calculator on this site shows both weights side by side.
Frequently asked questions
How many grams of protein per kg of body weight is normal?
The adult RDA is 0.8 g/kg per day. People who exercise regularly are advised 1.4 to 2.0 g/kg, and adults over 65 are advised at least 1.0 to 1.2 g/kg. The right figure for you depends on your health, so use a range and ask a clinician.
How much protein should a 180 pound person eat?
A 180 lb person weighs 81.65 kg. At the RDA of 0.8 g/kg that is 65 g a day, and at the 1.4 to 2.0 g/kg range for exercising adults it is 114 to 163 g. Pick the profile that matches your life.
Do men and women need different amounts of protein?
The RDA of 0.8 g/kg is given per kilogram of body weight, so the figure is the same for both. Because women often weigh less, the grams per day often come out lower. The exercise and over 65 ranges are also per kilogram.
Does protein intake need to be exact?
No. Published guidance is a range, and the tool prints one for that reason. Landing within the range on most days matters more than hitting one number. Day to day intake varies naturally, so treat the figure as a guide for a typical day.
How much protein is it per meal?
The sports nutrition position stand gives a general figure of 0.25 g/kg per serving, or 20 to 40 g, for maximizing muscle protein synthesis in exercising people. The calculator also divides your daily range by three or four meals.
How much protein should I eat on Ozempic, Wegovy, Mounjaro or Zepbound?
No drug-specific figure is published in the 2025 joint advisory. It gives the 0.8 g/kg RDA and says 1.2 to 1.6 g/kg per day has been proposed during active weight reduction. The GLP-1 protein calculator on this site shows both ranges. Ask your prescriber or dietitian.
Can PepTrac track my protein?
Yes. PepTrac for iPhone shows protein progress for the day beside calories and water, and its AI meal scan estimates protein from a photo. You set the goal. PepTrac is free to download, with an optional PepTrac Pro.
Is this protein calculator medical advice?
No. It estimates a range from published guidance. People with kidney disease, pregnant people, and anyone given protein or fluid limits by a clinician should follow that advice instead. A registered dietitian can set a target for your situation.
Sources
- American College of Lifestyle Medicine, American Society for Nutrition, Obesity Medicine Association, The Obesity Society (Obesity, 2025). Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory. Accessed October 3, 2026.
- Journal of the International Society of Sports Nutrition. International Society of Sports Nutrition Position Stand: protein and exercise. Accessed October 3, 2026.
- Journal of the American Medical Directors Association. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. Accessed October 3, 2026.
- Frontiers in Nutrition. Current Concepts and Unresolved Questions in Dietary Protein Requirements and Supplements in Adults (Phillips, 2017). Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Novo Nordisk). Ozempic (semaglutide) injection prescribing information. Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Novo Nordisk). Wegovy (semaglutide) prescribing information. Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Eli Lilly). Mounjaro (tirzepatide) injection prescribing information. Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Eli Lilly). Zepbound (tirzepatide) prescribing information. Accessed October 3, 2026.
Written and maintained by the team that builds PepTrac. Every calculator on this site runs the same tested math as the app. Read how we research, cite, and update pages in our editorial policy.
