Most protein advice falls into one of two camps. Either it parrots the 0.8 g/kg Recommended Dietary Allowance, which was set decades ago to prevent deficiency in sedentary adults, or it copies the latest bro-science fad and tells you to eat 1 gram per pound regardless of context.
Both miss the point. The right number depends on what you're trying to do, how often you train, and how old you are. This calculator picks the right multiplier from the peer-reviewed literature, plugs in your weight, and gives you a defensible target.
How this calculator works
Every multiplier in the calculator comes from a primary source. There are no made-up numbers, and there's no padding to sell you supplements.
- Build muscle: 1.6 to 2.2 g/kg/day. The lower bound is the plateau identified by Morton et al. 2018, a meta-analysis of 49 randomized controlled trials with 1,863 participants in the British Journal of Sports Medicine. The upper bound matches the ISSN position stand on protein and exercise (Jager et al. 2017).
- Lose fat (preserve muscle): 1.8 to 2.4 g/kg/day, or 2.3 to 3.1 g/kg of fat-free mass when body fat is provided. The total-weight range comes from the Longland et al. 2016 RCT in the American Journal of Clinical Nutrition, which showed that 2.4 g/kg/day during a deficit allowed lean mass gains. The FFM-based range comes from Helms et al. 2014 on natural bodybuilding contest preparation.
- Endurance performance: 1.2 to 1.6 g/kg/day, from the seminal Phillips and Van Loon 2011 review on dietary protein for athletes.
- General health: 0.8 to 1.2 g/kg/day, scaling up with training frequency. Adults 65+ get a floor bump to 1.0 g/kg/day per the PROT-AGE consensus paper (Bauer et al. 2013).
Per-meal distribution uses the rule from Schoenfeld and Aragon 2018: about 0.4 grams of protein per kilogram of body weight at each of four meals across the day, with a floor of 25 grams (35 grams for adults 65+) to clear the leucine threshold. We unpacked the meal-level science in our companion piece on the leucine threshold.
How much protein you actually need by goal
If you're trying to build muscle
The 2018 Morton meta-analysis is the closest thing the field has to a definitive answer. Pooling 49 RCTs and 1,863 participants, the authors found that protein supplementation significantly increased gains in muscle mass and strength when combined with resistance training. The dose-response curve flattened at 1.62 g/kg/day, with a 95% confidence interval of 1.03 to 2.20 g/kg/day.
Translation: if you eat less than about 1.6 g/kg/day, you're probably leaving muscle on the table. If you eat more than 2.2 g/kg/day, you're probably not gaining anything extra, but you're not hurting yourself either. The Antonio et al. 2014 high-protein trial pushed resistance-trained adults to 4.4 g/kg/day for eight weeks and saw no adverse effects on body composition, kidney function, or any other measured outcome. The ceiling, if there is one, is well above what most people will ever eat voluntarily.
If you're cutting
Protein needs go up in a deficit. The Longland 2016 trial randomized 40 young men to either 1.2 or 2.4 g/kg/day during a six-week energy deficit with intense exercise. Both groups lost fat. Only the high-protein group also gained lean mass. The 2.4 g/kg/day arm built about 1.2 kg of muscle while losing 4.8 kg of fat. The lower-protein arm just lost weight.
If you can measure your body fat, the more accurate approach is the Helms 2014 method: 2.3 to 3.1 grams per kilogram of fat-free mass. The leaner you get, the higher the multiplier needs to climb to protect what's left of your muscle.
If you're an endurance athlete
Endurance training increases protein needs less than resistance training does, but more than sedentary life does. Phillips and Van Loon's 2011 review settled on 1.2 to 1.6 g/kg/day for endurance athletes. The lower end is fine for casual runners. The upper end fits competitive cyclists, runners, and triathletes putting in serious volume.
If you just want to be healthy
If you don't train, the RDA of 0.8 g/kg/day prevents deficiency. But sedentary is rarely the goal, and even modest training pushes optimal intake up to 1.0 to 1.4 g/kg/day. For older adults, the PROT-AGE paper recommends a minimum of 1.0 to 1.2 g/kg/day to protect against sarcopenia, and 1.2 to 1.5 g/kg/day if any acute or chronic illness is in play. Both numbers assume the protein is paired with at least some resistance training. Protein without training won't reverse age-related muscle loss.
Worked examples (for quick reference)
Here are five common scenarios with the calculator output, so you can sanity-check the tool against your own numbers.
| Person | Goal | Daily protein | Per meal |
|---|---|---|---|
| 70 kg (154 lb) adult, trains seriously, under 40 | Build muscle | 112 to 154 g (target 133 g) | 28 g × 4 |
| 80 kg (176 lb) adult, trains seriously, 40-64 | Lose fat | 144 to 192 g (target 168 g) | 32 g × 4 |
| 65 kg (143 lb) adult, sedentary, 40-64 | General health | 52 to 78 g (target 65 g) | 26 g × 4 |
| 70 kg (154 lb) endurance athlete, under 40 | Endurance | 84 to 112 g (target 98 g) | 28 g × 4 |
| 75 kg (165 lb) adult 65+, trains seriously | Build muscle | 135 to 165 g (target 150 g) | 38 g × 4 |
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Take the Free Assessment Free • 2 minutes • No credit cardPer-meal distribution: the leucine threshold
Total daily protein is the dominant variable. Distribution matters at the margins. The reason is biological: each meal triggers a discrete pulse of muscle protein synthesis (MPS), and that pulse only fires fully when the meal contains enough leucine, the amino acid that switches MPS on.
Schoenfeld and Aragon's 2018 paper in the Journal of the International Society of Sports Nutrition recommends 0.4 g/kg of high-quality protein per meal across roughly four meals, totaling about 1.6 g/kg/day. For a 75 kg adult, that works out to 30 grams per meal. Each meal of that size contains roughly 2.5 grams of leucine, which is the threshold dose for a full MPS response in adults under 65.
Adults over 65 face anabolic resistance: a dulled MPS response that requires a bigger leucine spike to fully activate. The practical fix is a higher per-meal dose, around 35 to 40 grams, which corresponds to roughly 3 grams of leucine. We unpack the underlying biology in our piece on the leucine threshold and per-meal protein.
Three myths the calculator deliberately ignores
Myth 1: high protein damages your kidneys
This claim has persisted for decades despite consistent evidence against it. The most rigorous test came from Devries et al. 2018, a systematic review and meta-analysis published in the Journal of Nutrition that pooled 28 randomized trials. The authors found no clinically meaningful difference in glomerular filtration rate (the standard kidney function metric) between people on higher-protein and lower-protein diets. Antonio's 2014 trial pushed protein to 4.4 g/kg/day for eight weeks with no kidney issues. Healthy kidneys handle high protein loads without trouble.
The exception is people with pre-existing chronic kidney disease, who should follow medical guidance from a nephrologist. The calculator is built for healthy adults.
Myth 2: you can only absorb 30 grams of protein per meal
This one comes from a misreading of the same MPS dose-response research. The 30-gram figure refers to the point at which a single meal maximally stimulates MPS, not the point where extra protein gets flushed unused. Anything above the MPS-saturating dose is still digested and absorbed. It's used for other purposes (gluconeogenesis, amino acid pool replenishment, immune function), and any excess can become substrate for fat tissue, but only if your total calories also exceed maintenance.
Schoenfeld and Aragon (2018) directly addressed this in a paper titled "How much protein can the body use in a single meal for muscle-building?" Their answer: from a pure muscle-building standpoint, the per-meal cap is approximately 0.4 g/kg, which is about 30 grams for a typical adult. From a total nutrition standpoint, there is no cap.
Myth 3: protein timing makes or breaks your gains
The "anabolic window" is the most-marketed and least-supported timing claim in fitness. We covered it in detail in our piece on why the anabolic window is a myth. Total daily intake matters far more than whether you drink your shake within 30 minutes of your last set. The calculator gives you a daily total. How you split it across the day matters at the margins. When exactly you eat each portion almost never matters.
When to ignore this calculator
The calculator is built for healthy adults using common goal categories. A few situations require professional input rather than a generic tool.
- Chronic kidney disease. Protein recommendations for CKD are different and depend on stage. Talk to a nephrologist or registered dietitian.
- Pregnancy and lactation. Protein needs rise during the second and third trimesters and during lactation. Defer to your obstetric care team for individualized targets.
- Eating disorders or recent recovery. A registered dietitian who specializes in eating disorders is a better fit than any generic calculator.
- Diagnosed metabolic conditions. Diabetes, gout, and PKU all interact with dietary protein in ways that need a clinician's input.
For everyone else, the numbers above are a defensible starting point. Hit the daily target consistently for three to four weeks and adjust based on the scale, the mirror, and your training performance.
Related reading
References
- 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." Br J Sports Med. 2018;52(6):376-384. doi:10.1136/bjsports-2017-097608
- Jager R, Kerksick CM, Campbell BI, et al. "International Society of Sports Nutrition Position Stand: protein and exercise." J Int Soc Sports Nutr. 2017;14:20. doi:10.1186/s12970-017-0177-8
- Helms ER, Aragon AA, Fitschen PJ. "Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation." J Int Soc Sports Nutr. 2014;11:20. doi:10.1186/1550-2783-11-20
- Longland TM, Oikawa SY, Mitchell CJ, Phillips SM, et al. "Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial." Am J Clin Nutr. 2016;103(3):738-746. doi:10.3945/ajcn.115.119339
- 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." J Am Med Dir Assoc. 2013;14(8):542-559. doi:10.1016/j.jamda.2013.05.021
- Schoenfeld BJ, Aragon AA. "How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution." J Int Soc Sports Nutr. 2018;15:10. doi:10.1186/s12970-018-0215-1
- Phillips SM, Van Loon LJ. "Dietary protein for athletes: from requirements to optimum adaptation." J Sports Sci. 2011;29 Suppl 1:S29-S38. doi:10.1080/02640414.2011.619204
- Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T. "The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals." J Int Soc Sports Nutr. 2014;11:19. doi:10.1186/1550-2783-11-19
- Devries MC, Sithamparapillai A, Brimble KS, Banfield L, Morton RW, Phillips SM. "Changes in kidney function do not differ between healthy adults consuming higher- compared with lower- or normal-protein diets: a systematic review and meta-analysis." J Nutr. 2018;148(11):1760-1775. doi:10.1093/jn/nxy197
Frequently Asked Questions
How much protein do I need per day?
For a healthy adult who trains regularly, the evidence-based range is 1.6 to 2.2 grams of protein per kilogram of body weight per day. That is roughly 0.73 to 1.0 grams per pound. The 2018 meta-analysis by Morton and colleagues in the British Journal of Sports Medicine, which pooled 49 randomized controlled trials and 1,863 participants, found that gains in muscle mass and strength plateaued around 1.62 g/kg/day. The ISSN position stand on protein and exercise recommends 1.4 to 2.0 g/kg/day for active adults.
What is the protein RDA, and is it enough?
The Recommended Dietary Allowance (RDA) for protein is 0.8 g/kg of body weight per day. The RDA is a deficiency floor designed to prevent nitrogen imbalance in sedentary adults. It is not a target for muscle gain, fat loss, or athletic performance. Active people, older adults, people in a calorie deficit, and anyone trying to build muscle need substantially more, typically 1.4 to 2.4 g/kg/day depending on goal.
How much protein per meal is enough?
Schoenfeld and Aragon (2018) recommend roughly 0.4 grams of protein per kilogram of body weight at each of four meals across the day. For a 75 kg adult, that is about 30 grams per meal. Each meal should clear the leucine threshold (about 2.5 g of leucine, or roughly 25 to 35 grams of high-quality protein) to fully activate muscle protein synthesis. Adults over 65 typically need a slightly higher per-meal dose of 35 to 40 grams because of anabolic resistance.
Does high protein damage your kidneys?
No, not in healthy adults. A 2018 systematic review and meta-analysis by Devries and colleagues, published in the Journal of Nutrition, pooled 28 randomized trials and found no clinically meaningful difference in kidney function (measured by glomerular filtration rate) between people on higher-protein and lower-protein diets. People with pre-existing chronic kidney disease are a different case and should follow medical guidance from a clinician.
How much protein when cutting or losing fat?
When you are in a calorie deficit and trying to preserve or build muscle, protein needs go up. The Longland et al. 2016 trial in the American Journal of Clinical Nutrition found that 2.4 g/kg/day during a deficit allowed participants to gain lean mass while losing fat, compared to 1.2 g/kg/day which only produced fat loss. Helms et al. 2014, focused on natural bodybuilders, recommend 2.3 to 3.1 grams per kilogram of fat-free mass during contest prep.
How much protein do older adults need?
The PROT-AGE consensus paper (Bauer et al. 2013) recommends 1.0 to 1.2 g/kg/day for healthy adults over 65, and 1.2 to 1.5 g/kg/day for those with acute or chronic disease. Older adults trying to build or preserve muscle through resistance training should aim for the upper end of this range, around 1.2 to 1.6 g/kg/day, with each meal hitting at least 35 to 40 grams of protein to overcome anabolic resistance.
Does this calculator work for plant-based diets?
Yes, with one caveat. The total daily target is the same. Plant proteins generally carry less leucine per gram than animal proteins, so per-meal portions on a fully plant-based diet often need to be slightly larger to hit the leucine threshold. A 2024 study in Current Developments in Nutrition (Smith et al.) showed that completely plant-based diets can support maximal muscular development in adult athletes when total protein and leucine intake are adequate.