Protein Calculator
Protein is the most studied macronutrient in sports science, and the research is unusually consistent: most people are eating less than they need for their goals. The official recommended dietary allowance of 0.8 grams per kilogram of body weight was set as a minimum to prevent deficiency in sedentary adults. It was never intended as an optimal target.
Research consistently shows that 0.8 g/kg/day is a floor, not a ceiling. For active individuals, older adults, and anyone trying to change their body composition, the evidence points to significantly higher intakes. This calculator uses verified ranges derived from peer-reviewed guidelines and clinical trials to give you a target that actually matches what you’re trying to accomplish.
How Protein Intake Is Calculated
Your protein target is calculated as a function of body weight and adjusted for activity level and goal. The base unit is grams per kilogram of body weight per day (g/kg/day). If you enter your weight in pounds, it is converted to kilograms by dividing by 2.205.
The International Society of Sports Nutrition recommends 1.4 to 2.0 g/kg/day for exercising individuals to build and maintain muscle mass (Jager et al., 2017, PMID: 28642676). The upper end of that range applies during intense training blocks or when training volume is high. The calculator scales within that range based on your activity level and shifts higher or lower depending on your stated goal.
For weight loss, targets are set toward the upper range of 1.6 to 2.4 g/kg/day. During a caloric deficit, muscle tissue is at risk of breakdown for energy. Higher protein intake counteracts this. For sedentary individuals not pursuing specific performance or physique goals, the target stays near the WHO minimum of 0.83 g/kg/day, with an adjustment upward for older adults.
Understanding Your Results
Your result is a daily gram target. Here is how to interpret it based on the research.
Sedentary adults (0.8-1.0 g/kg/day). This range covers the WHO/FAO minimum of 0.83 g/kg/day for healthy, inactive adults. It prevents protein deficiency and supports basic tissue repair. If you are over 65, even without formal exercise, research supports moving to at least 1.0-1.2 g/kg/day to offset age-related muscle loss.
Lightly to moderately active (1.0-1.4 g/kg/day). Regular movement above baseline increases protein turnover in muscle tissue. Intakes of 1.2 to 1.6 g/kg/day represent a more ideal target than the RDA for optimal health and healthy aging (Phillips et al., 2016, PMID: 26960445).
Muscle gain (1.6-2.2 g/kg/day). This is where the research is particularly clear. A meta-analysis of 49 studies covering 1,863 participants found that protein intakes above 1.6 g/kg/day did not further contribute to gains in fat-free mass beyond that threshold (Morton et al., 2018, PMID: 28698222). Eating at 1.6 g/kg/day gets you most of the benefit. Going to 2.2 g/kg/day provides a safety buffer, especially for advanced trainees.
Weight loss (1.6-2.4 g/kg/day). Protein above the RDA attenuates lean mass loss during energy restriction and increases lean mass during resistance training (Hudson et al., 2020, PMID: 31794597). Athletes in a caloric deficit should aim for 1.8 to 2.0 g/kg/day to preserve muscle while losing fat (Phillips and Van Loon, 2011, PMID: 22150425).
When to Use This Calculator
Starting a resistance training program. When you begin lifting, your muscle protein synthesis rate increases substantially. Knowing your protein target early prevents the common mistake of training hard but eating too little protein to support adaptation.
Cutting weight for a specific goal. Dieting without adequate protein is one of the most reliable ways to lose muscle alongside fat. This calculator sets your protein floor for the deficit phase, so the weight you lose is predominantly fat.
Eating for healthy aging. Adults over 65 face accelerated muscle loss (sarcopenia) even with adequate calorie intake. A minimum of 1.0 to 1.2 g/kg/day is the research-supported target for this group, compared to the 0.83 g/kg/day minimum set for younger sedentary adults.
Returning after a layoff. After illness, injury, or extended time away from training, protein needs are elevated as the body rebuilds lost muscle mass. Using a calculated target rather than estimating makes the recovery phase more effective.
Limitations
This calculator estimates your needs based on body weight, not fat-free mass. Two people at the same weight can have very different amounts of muscle tissue, which drives protein requirements. A 90 kg person with 25% body fat needs less protein than a 90 kg person with 12% body fat, but the calculator will give them the same number.
The calculator does not account for distribution. Total daily protein matters, but so does how you spread it. The ACSM, AND, and DC joint position statement recommends 0.25 to 0.3 grams per kilogram per meal across 3 to 4 meals to optimize muscle protein synthesis throughout the day. Eating all your protein in one sitting is less effective than spreading it out.
Individual protein metabolism varies. Factors like gut health, dietary protein source, and training status all affect how efficiently your body uses the protein you eat. The ranges provided are population averages. Your actual optimal intake may fall slightly above or below.
Tips for Accuracy
Use your body weight in kilograms for the math. Even small errors in weight entry compound into meaningful differences in your daily target. Weigh yourself in the morning, after using the bathroom, for the most consistent baseline.
Select your activity level honestly. Office workers who exercise for 45 minutes three times a week are lightly active, not highly active. The activity multiplier has a larger effect on your target than most people realize.
Track protein source as well as grams. Animal proteins (meat, eggs, dairy) are complete proteins with high bioavailability. Plant proteins often require combining sources to cover the full amino acid spectrum. If your diet is primarily plant-based, aim toward the higher end of your calculated range.
Distribute across meals. Hit your daily gram target across 3 to 4 meals rather than concentrating it in one or two. This maximizes muscle protein synthesis throughout the day and tends to reduce hunger compared to low-protein eating.
Adjust based on results over 4-6 weeks. If you are gaining weight too fast, pull calories first before reducing protein. If muscle gain is stalled despite training, check that protein is consistently at the 1.6 g/kg minimum before adding more volume to your program.
Frequently Asked Questions
Does eating more protein than 1.6 g/kg/day build more muscle? Probably not significantly. A large meta-analysis of 49 studies found that gains in fat-free mass plateau at approximately 1.6 g/kg/day during resistance training (Morton et al., 2018, PMID: 28698222). Eating more than this provides a buffer against daily variation but is unlikely to produce meaningfully greater muscle growth.
Is high protein intake bad for your kidneys? Current evidence does not support the claim that higher protein harms kidneys in healthy individuals. This concern originates from research on people with pre-existing kidney disease, for whom dietary protein restriction is clinically appropriate. For healthy adults, protein intakes up to 2.5 g/kg/day show no adverse kidney effects in the available literature.
How much protein do older adults need? More than the standard RDA. The 0.83 g/kg/day minimum is set for young adults and underestimates the needs of people over 65. Research supports a minimum of 1.0 to 1.2 g/kg/day for sarcopenia prevention, with intakes of 1.2 to 1.6 g/kg/day providing additional benefit for active older adults (Phillips et al., 2016, PMID: 26960445).
Do endurance athletes need as much protein as strength athletes? They need more than the RDA but generally less than heavy strength athletes. Endurance athletes should target 1.2 to 1.6 g/kg/day. Protein intake supports muscle repair from repeated endurance sessions and helps spare glycogen, but the demands are lower than those of heavy resistance training (Jager et al., 2017, PMID: 28642676).
Should I eat more protein on rest days? The evidence supports maintaining your protein intake on rest days rather than dropping it. Muscle protein synthesis remains elevated for 24 to 48 hours after a training session, and protein is still required to complete that repair process. Reducing protein on rest days undermines the adaptation you trained for.
References
- Hudson, J.L. et al. (2020). Protein Intake Greater than the RDA Differentially Influences Whole-Body Lean Mass Responses to Purposeful Catabolic and Anabolic Stressors. Advances in Nutrition, 11(3), 548-558. PMID: 31794597.
- Jager, R. et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14, 20. PMID: 28642676.
- Morton, R.W. et al. (2018). 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, 52(6), 376-384. PMID: 28698222.
- Phillips, S.M., Chevalier, S. & Leidy, H.J. (2016). Protein “requirements” beyond the RDA: implications for optimizing health. Applied Physiology, Nutrition, and Metabolism, 41(5), 565-572. PMID: 26960445.
- Phillips, S.M. & Van Loon, L.J.C. (2011). Dietary protein for athletes: from requirements to optimum adaptation. Journal of Sports Sciences, 29(S1), S29-S38. PMID: 22150425.
- WHO/FAO/UNU (2007). Protein and Amino Acid Requirements in Human Nutrition. WHO Technical Report Series, 935. Geneva: World Health Organization.