🥩 Protein Calculator

What is protein and how much do you need?

Proteinis the macronutrient responsible for building and repairing tissue, manufacturing enzymes and hormones, supporting immune function, and — for active individuals — driving muscle protein synthesis (MPS). The official US RDA, set in the 1940s and last revised in 2005, is just 0.8 g per kg of body weight, a figure designed to prevent deficiency in sedentary adults rather than to optimize athletic performance or body composition. Modern evidence, summarized in the ISSN Position Stand on Protein and Exercise (Jager et al. 2017) and the comprehensive meta-analysis by Morton et al. 2018 in the British Journal of Sports Medicine, demonstrates that active individuals need substantially more — commonly 1.6– 2.2 g/kg, and up to 2.6 g/kg in specific contexts.

How protein needs are calculated

Protein requirements are typically expressed in grams per kilogram of body weight per day, with the multiplier set by activity level, age, and goal:

• Sedentary adults:0.8–1.0 g/kg
• Recreationally active:1.2–1.6 g/kg
• Resistance training / hypertrophy:1.6–2.2 g/kg
• Cutting (caloric deficit) or older adults: 2.0–2.6 g/kg

Worked example: a 70 kg recreational lifter in a modest fat-loss phase. Targeting the upper end of the cutting range (2.4 g/kg) gives 168 g of protein per day, or approximately 165 g rounded down. To optimize the muscle protein synthesis response, that total is best distributed across 4 meals of ~40 g each, spaced 3–5 hours apart, with each meal containing roughly 2.5–3 g of leucine (the amino acid that triggers MPS). At 4 kcal/g, 165 g of protein contributes 660 kcal of the daily total.

Why protein matters for your training

Protein is the only macronutrient whose intake directly determines muscle preservation. During a caloric deficit, adequate protein is what separates fat loss from weight loss that includes lean tissue. The Helms et al. 2014 review of natural bodybuilders found that protein at 2.3–3.1 g/kg of fat-free mass was needed to fully preserve muscle in lean dieters. Beyond body composition, protein is the most satiating macronutrient gram for gram, which makes adherence to any calorie target dramatically easier.

For older adults, protein also defends against sarcopenia, the age-related loss of muscle mass that underlies frailty and falls. The PROT-AGEconsensus group recommends 1.0–1.2 g/kg for healthy older adults and up to 1.5 g/kg in those with acute or chronic disease — well above the outdated 0.8 g/kg RDA.

Limitations of this calculator

Protein math is more nuanced than a single multiplier suggests:

• Using total body weight as the denominator overestimates needs in individuals with high body fat. A 100 kg person at 35% body fat has only ~65 kg of lean mass, and using lean mass as the basis yields a more accurate target.
• Distribution matters: a single 150 g protein meal is less effective for MPS than four 40 g servings, due to the leucine threshold and the 3–5 hour MPS refractory window.
• Protein quality varies. The Digestible Indispensable Amino Acid Score (DIAA) ranks animal proteins (whey, eggs, dairy, meat) above most plant sources. Plant-based eaters need slightly higher totals or strategic combining.
• The calculator does not account for training day vs rest day nuance, although evidence suggests daily totals matter more than day-to-day variation.
• Very high intakes (above ~2.5 g/kg) show diminishing returns for most people and may displace other macronutrients without added benefit.

When to consult a professional

Speak with a physician or registered dietitian before adopting a high-protein diet if any of the following apply:

• Chronic kidney disease (CKD)or reduced glomerular filtration rate — protein intake must be individualized and may need to be limited.
• A history of gout, particularly if you plan to increase intake from purine-rich animal sources.
• Pregnancy or breastfeeding, which raise protein needs but within specific clinical recommendations.
• History of an eating disorder— rigid macronutrient targets can reinforce restrictive patterns.
• You are over 65 with multiple comorbidities or taking medications affecting kidney function, where the right protein target balances sarcopenia prevention with safety.