Protein Calculator — Daily Needs
Calculate daily protein needs by weight, activity and goals. ISSN-backed formula with Boer lean-mass estimation and meal distribution. Free.
What to calculate next?
CalcVita. (2026). Protein Calculator — Daily Needs. CalcVita. Retrieved September 8, 2026, from https://calcvita.com/en/calculators/protein
Suggested article
Protein Intake Guide: How Much You Really Need
Learn how much protein you need based on your activity level, goals, and age — plus how to distribute it across meals for maximum muscle protein synthesis.
Read the full article →Quick guide to the protein calculator
This protein calculator uses ISSN-backed formulas to estimate your daily protein needs. It considers your weight, height, age, sex, activity level, and goal to deliver a personalized recommendation. Lean body mass is estimated via the Boer equation (1984) — the gold standard for non-invasive lean mass estimation — unless you provide your body fat percentage directly.
How the calculation works
The engine starts with a base protein requirement per kilogram (0.8 g/kg for sedentary up to 2.0 g/kg for competitive athletes), then applies goal-specific adjustments: +0.3 g/kg for muscle gain or recomposition, +0.4 g/kg for weight loss (to preserve lean tissue during a caloric deficit). An age factor adds 0.2-0.3 g/kg for adults over 50 to counteract age-related muscle loss. The total is capped at 2.4 g/kg as higher intakes show diminishing returns (Morton et al., 2018).
Understanding each field
Weight (kg)
Your current body weight in kilograms. This is the primary variable in protein calculations.
Height (cm)
Used in the Boer lean body mass formula when body fat percentage is not provided.
Age (years)
Adults over 50 receive a higher protein recommendation due to increased anabolic resistance and sarcopenia risk.
Biological sex
Affects lean body mass estimation: the Boer formula uses different coefficients for males and females.
Body fat percentage (optional)
If known, provides a more accurate lean body mass calculation. Typical ranges: 10-20% for men, 20-30% for women.
Activity level
Ranges from sedentary (0.8 g/kg base) to competitive athlete (2.0 g/kg base). Choose the level that best reflects your regular training volume and intensity.
Primary goal
Muscle gain and recomposition add +0.3 g/kg, weight loss adds +0.4 g/kg. Maintaining bodyweight uses the base recommendation.
Interpreting your results
The calculator provides a recommended daily intake (grams), a range (minimum-maximum), and a tier classification: Minimum (below 1.2 g/kg — adequate for sedentary lifestyles), Recommended (1.2-1.8 g/kg — optimal for most active individuals), or Athlete (above 1.8 g/kg — for high-volume training or competitive sport). The meal distribution suggests how to spread protein across the day for optimal muscle protein synthesis.
Limitations
This calculator provides estimates based on population-level research. Individual needs may vary based on genetics, training status, health conditions, and dietary factors. It does not account for specific medical conditions (e.g., kidney disease). Always consult a registered dietitian or physician for personalized medical nutrition therapy.
Practical tips
- Spread your protein across 3-6 meals to maximize muscle protein synthesis — aim for 20-40 g per meal (Schoenfeld & Aragon, 2018).
- Combine higher protein intake with resistance training for best results in muscle gain and body recomposition.
- Prioritize complete protein sources (eggs, dairy, meat, fish, soy) that provide all essential amino acids, especially leucine.
Scientific sources
- Jäger R et al. (2017) — ISSN Position Stand: Protein and Exercise. J Int Soc Sports Nutr. 14:20. PMID 28642676
- Morton RW et al. (2018) — Protein supplementation and resistance training gains in muscle mass. Br J Sports Med. 52(6):376-384. PMID 28698222
- WHO/FAO/UNU (2007) — Protein and amino acid requirements in human nutrition. Technical Report Series 935.
- Longland TM et al. (2016) — Higher vs. lower dietary protein during cutting in trained young men. Am J Clin Nutr. 103(3):738-746. PMID 26817506
- Schoenfeld BJ & Aragon AA (2018) — How much protein can the body use per meal for muscle-building? JISSN. 15:10. PMID 29497353
Frequently asked questions
- How much protein do I need per day?
- The International Society of Sports Nutrition (ISSN, 2017) recommends 1.4-2.0 g/kg/day for active individuals. Sedentary adults need at least 0.8 g/kg/day (WHO/FAO/UNU). Your optimal intake depends on activity level, goals, and age. Older adults (50+) benefit from higher intakes (1.0-1.3 g/kg) to prevent sarcopenia.
- Can I eat too much protein?
- For healthy individuals, intakes up to 2.0-2.4 g/kg/day show no adverse effects on kidney function or bone health (Morton et al., 2018). However, those with pre-existing kidney disease should consult a physician. A systematic review in the British Journal of Sports Medicine confirmed that higher protein diets (up to 3.5 g/kg) in trained individuals showed no harmful effects on metabolic markers.
- How is the protein requirement calculated?
- Our calculator uses a base protein-per-kg value determined by your activity level (from 0.8 g/kg for sedentary to 2.0 g/kg for athletes), then adjusts for your goal (+0.3-0.4 g/kg for muscle gain or weight loss) and age (+0.2-0.3 g/kg for adults over 50). Lean body mass is estimated using the Boer formula (1984) when body fat percentage is not provided.
- Why do I need more protein when losing weight?
- During a caloric deficit, higher protein intake (1.2-1.6 g/kg) helps preserve lean muscle mass while losing fat. A 2016 study by Longland et al. in the American Journal of Clinical Nutrition showed that participants consuming 2.4 g/kg during a deficit retained more muscle and lost more fat compared to a 1.2 g/kg group. Protein also increases satiety, helping control appetite.
- When is the best time to eat protein?
- Research supports spreading protein intake evenly across 3-6 meals throughout the day, with 20-40 g per meal to maximize muscle protein synthesis (MPS). Post-exercise, consuming 20-40 g of high-quality protein within 2 hours optimizes recovery (Schoenfeld & Aragon, 2018). However, total daily intake matters more than precise timing.
- What are the best sources of protein?
- Complete proteins containing all essential amino acids include: lean meats, poultry, fish, eggs, dairy, soy, and quinoa. Animal sources typically have higher bioavailability and leucine content, which is key for MPS. Plant-based diets can meet protein needs by combining legumes, grains, nuts, and seeds. The DIAAS (Digestible Indispensable Amino Acid Score) ranks eggs, dairy, and meat highest for protein quality.
More calculators