Free protein calculator: grams of protein per day for weight loss, strength training, older age and GLP-1 medicines, with food amounts and kidney cautions.
Key takeaways
- The 2025-2030 Dietary Guidelines for Americans promote 1.2 to 1.6 g of protein per kg of body weight a day, above the 0.8 g/kg RDA.[3]
- With the same calories, higher-protein diets helped keep lean mass and resting energy use in a meta-analysis of 24 trials.[4]
- Muscle gains from extra protein with strength training leveled off at about 1.6 g/kg a day.[5]
- Adults over 65 are advised at least 1.0 to 1.2 g/kg a day, except some people with severe kidney disease.[6]
- Nutrition and obesity societies advise against staying at or above 2 g/kg a day for long periods.[1]
In short: Most healthy adults need at least 0.8 grams of protein per kilogram of body weight a day, the RDA. While losing weight, many studies and the 2025-2030 Dietary Guidelines for Americans use more, about 1.2 to 1.6 g/kg, to help protect muscle. This protein calculator turns those ranges into grams for your weight and situation. If you have kidney disease, set your target with your clinician.
Protein calculator
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Educational estimate, not medical advice. Talk with a healthcare professional before changing how you eat, move or take medicines.
How this works
The RDA, 0.8 g of protein per kg of body weight a day, is the amount that covers the needs of nearly all healthy adults. It is a minimum, not an optimum.
Studies of weight loss often use 1.2 to 1.6 g/kg to help keep muscle; with strength training, benefits level off around 1.6 g/kg (up to about 2.2). For adults 65 and older, expert groups suggest 1.0 to 1.2 g/kg.
If your BMI is 30 or more, we use the weight at a BMI of 25 for your height instead of your full weight.
Limits
- Kidney disease or reduced kidney function: do not raise protein without your clinician.
- These are ranges studied in research, not a personal prescription. A registered dietitian can turn them into meals that fit you.
- For anyone under 18, needs depend on growth; ask a pediatrician.
Sources
- National Academies: Dietary Reference Intakes for energy and macronutrients (2005)
- Morton RW et al. Protein supplementation and resistance-training-induced gains: meta-analysis. Br J Sports Med 2018;52:376-384
- Bauer J et al. Evidence-based recommendations for optimal dietary protein intake in older people (PROT-AGE). JAMDA 2013;14:542-559
Why protein matters when you lose weight
When you eat less, your body loses some muscle along with fat. Protein, together with strength training, helps limit that. In a meta-analysis of 24 trials, people on reduced-calorie diets higher in protein lost slightly more fat, kept more lean mass and saw a smaller drop in resting energy use than people eating the same calories with standard protein. Protein also takes more energy to digest than carbs or fat and, in several of those trials, helped people feel fuller.
What the guidelines say now
- The RDA (0.8 g/kg) is the long-standing minimum for healthy adults. A 2025 joint advisory from four nutrition and obesity societies notes that it is being reviewed by the National Academies.
- The 2025-2030 Dietary Guidelines for Americans promote 1.2 to 1.6 g/kg a day for the public. Some nutrition scientists have questioned how broadly that applies, noting the evidence focused mainly on weight management, so it is reasonable to see it as a range rather than a rule (checked on 2026-10-06).
- Strength training: a meta-analysis of 49 trials found that gains in lean mass from adding protein leveled off at around 1.6 g/kg a day.
- Adults over 65: the PROT-AGE expert group recommends at least 1.0 to 1.2 g/kg, 1.2 g/kg or more for those who exercise, and 1.2 to 1.5 g/kg for many older adults with acute or chronic illness.
- Upper limit: the 2025 advisory says protein should not fall below 0.4 to 0.5 g/kg and that staying at or above 2 g/kg for long periods should be avoided.
| Item | Low | High |
|---|---|---|
| Lowest floor, 2025 advisory | 0.4 g/kg | 0.5 g/kg |
| Adults over 65, PROT-AGE | 1 g/kg | 1.2 g/kg |
| During weight loss, advisory and DGA 2025-2030 | 1.2 g/kg | 1.6 g/kg |
| Over 65 with acute or chronic illness, PROT-AGE | 1.2 g/kg | 1.5 g/kg |
The RDA, 0.8 g/kg, is the minimum for healthy adults; staying at or above 2 g/kg for long periods should be avoided. Kidney disease is an exception: ask your clinician.
Source: 2025 joint advisory (Am J Clin Nutr), realfood.gov and PROT-AGE (JAMDA 2013) (checked on October 6, 2026)
If you take a GLP-1 medicine
GLP-1 medicines such as semaglutide and tirzepatide lower appetite, so many people eat much less. The 2025 advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society lists muscle and bone loss and nutrient shortfalls among the challenges, and stresses resistance training and an appropriate diet to protect muscle. It also notes that for people with obesity, basing protein on full body weight can overestimate needs, which is why this calculator uses a lower reference weight when BMI is 30 or more. Our guides on muscle loss on weight-loss injections and eating on a GLP-1 go further. Your prescriber or a dietitian can set a target that fits your medicine and health.
Kidney disease and other cautions
People with reduced kidney function may need to limit protein. The PROT-AGE group, for example, makes an exception to its higher targets for older adults with severe kidney disease who are not on dialysis. If you have kidney disease, diabetes with kidney involvement, or are pregnant or breastfeeding, do not raise protein without talking to your clinician.
Foods that make it easier
A target of 100 grams sounds like a lot until you see it across a day. Approximate amounts from USDA FoodData Central:
- Animal foods: 3 oz roasted chicken breast, about 26 g; 3 oz canned light tuna, about 22 g; 3 oz cooked salmon, about 19 g; 1 cup 2% cottage cheese, about 23 g; 1 large egg, about 6 g.
- Plant foods: ½ cup firm tofu, about 22 g; 1 cup cooked lentils, about 18 g; 1 cup cooked black beans, about 15 g; 2 tablespoons peanut butter, about 7 g.
A practical approach is to include a protein food at every meal and in one snack. Shakes can help on busy days; our guide to protein shakes compares types and what to look for. For a full plan, start with the calorie calculator; the macro calculator fits your protein into your daily calories, and our high-protein diet guide and recipes make it practical. For the bigger picture, see how a calorie deficit works.
Protein works best with strength training
In the meta-analysis of 49 trials, extra protein boosted gains in muscle size and strength during resistance training. Two or more days a week of muscle-strengthening activity is part of the U.S. Physical Activity Guidelines for adults, and it is the other half of protecting muscle while you lose weight. Our strength training guide has a beginner plan with or without equipment.
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- How much protein a day is right for me, given my kidney function and health?
- Should my protein target be based on my current weight or another reference weight?
- If I take a GLP-1 medicine, how can I get enough protein when my appetite is low?
- Would seeing a registered dietitian help me plan meals around my target?
- What strength training is safe for me to protect muscle while I lose weight?
Frequently asked questions
How much protein do I need per day to lose weight?
Many studies of weight loss use about 1.2 to 1.6 grams per kilogram of body weight a day, and the 2025-2030 Dietary Guidelines promote the same range. For a 180-pound (82 kg) adult with a BMI under 30, that is roughly 98 to 131 grams. Your clinician or a dietitian can adjust it for your health.
Should I use my current weight or my goal weight?
For people with a BMI under 30, current weight works. For higher BMIs, experts note that full body weight can overestimate needs, so the calculator uses the weight at a BMI of 25 for your height.
Can you eat too much protein?
Yes. A 2025 society advisory says prolonged intakes at or above 2 g/kg a day should be avoided, and people with kidney disease may need less protein. More is not always better.
Do I need protein shakes?
No. Food can cover most targets. Shakes are a convenient option when appetite is low or on busy days.
How much protein do older adults need?
Expert groups suggest at least 1.0 to 1.2 g/kg a day for adults over 65, and more for those who are active or ill, unless kidney function is severely reduced.
References
- Mozaffarian D, Agarwal M, Aggarwal M, et al.. Nutritional priorities to support GLP-1 therapy for obesity: a joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. American Journal of Clinical Nutrition, 2025. doi:10.1016/j.ajcnut.2025.04.023 · PMID 40450457 (accessed October 6, 2026) Society statement
- Dietary Guidelines for Americans, 2025-2030. U.S. Department of Health and Human Services and U.S. Department of Agriculture, 2026. (accessed October 6, 2026) Guideline
- Pasiakos SM, Davis TA, Klurfeld DM, Neuhouser ML, Rodriguez NR, Tomé D. Perspectives on the Protein Recommendations in the 2025-2030 Dietary Guidelines for Americans. Journal of Nutrition, 2026. doi:10.1016/j.tjnut.2026.101754 · PMID 42498030 (accessed October 6, 2026) Review
- Wycherley TP, Moran LJ, Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. American Journal of Clinical Nutrition, 2012. doi:10.3945/ajcn.112.044321 · PMID 23097268 (accessed October 7, 2026) Meta-analysis
- Morton RW, Murphy KT, McKellar SR, et al.. 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. British Journal of Sports Medicine, 2018. doi:10.1136/bjsports-2017-097608 · PMID 28698222 (accessed October 7, 2026) Meta-analysis
- Bauer J, Biolo G, Cederholm T, et al.. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. Journal of the American Medical Directors Association, 2013. doi:10.1016/j.jamda.2013.05.021 · PMID 23867520 (accessed October 6, 2026) Society statement
- Westerterp KR. Diet induced thermogenesis. Nutrition & Metabolism, 2004. doi:10.1186/1743-7075-1-5 · PMID 15507147 (accessed October 7, 2026) Review
- Physical Activity Guidelines for Americans, 2nd edition: top 10 things to know. U.S. Department of Health and Human Services (ODPHP). (accessed October 7, 2026) Guideline
- FoodData Central (SR Legacy, April 2018 release). U.S. Department of Agriculture, Agricultural Research Service, 2018. (accessed October 7, 2026) Government page
Facts checked on October 6, 2026
Educational information, not medical advice. Talk with a qualified healthcare professional about your own situation. In an emergency call 911.