Protein Calculator

Protein is the only macronutrient your body cannot synthesize from scratch — every gram must come from food. But how much you actually need depends on a surprisingly complex interplay of body composition, training stimulus, and even your age. The numbers above are grounded in current sports science, not marketing materials.

Muscle Protein Synthesis and the Leucine Threshold
Each time you eat protein, your body triggers a process called muscle protein synthesis (MPS) — the cellular machinery that builds and repairs muscle fibres. MPS is gated by leucine, a branched-chain amino acid. Research shows you need roughly 2–3g of leucine per meal to maximally stimulate MPS. This explains why a single serving of chicken breast (about 30g protein, ~2.5g leucine) is effective, while a handful of peanuts (5g protein, ~0.4g leucine) barely moves the needle on its own.

The Anabolic Window Is Wider Than You Think
The idea that you must consume protein within 30 minutes post-workout — the so-called "anabolic window" — has been substantially revised. A 2013 meta-analysis by Aragon and Schoenfeld showed that total daily protein intake matters far more than precise timing. That said, spreading protein across 4–5 meals of roughly 25–40g each consistently outperforms concentrating it in one or two large servings, because each meal independently triggers an MPS spike that lasts approximately 3–5 hours.

Protein Sources: What the Numbers Actually Say
Not all protein is equal when scored by DIAAS (Digestibility-Corrected Amino Acid Score), which measures how well a protein meets human amino acid requirements after digestion. Chicken breast provides around 31g protein per 100g with a DIAAS near 1.0 (the maximum). Eggs deliver about 13g per 100g with excellent bioavailability. Greek yogurt contributes roughly 10g per 100g and is rich in leucine. Lentils offer about 9g per 100g but score lower on DIAAS due to limiting amino acids — though this is easily compensated by eating varied plant proteins across a day. Tofu provides around 8g per 100g with a DIAAS of 0.97, making it surprisingly competitive with animal sources when consumed in adequate quantities.

Age Changes Everything
Older adults (60+) experience anabolic resistance — the same leucine dose that fully stimulates MPS in a 25-year-old may only partially stimulate it at 65. This is why protein recommendations for older adults trend 20–30% higher than for younger populations. The current evidence-based recommendation for adults over 65 is 1.2–1.6g/kg, compared to 0.8–1.2g/kg for sedentary younger adults. If you are over 60, consider moving one activity level up from your actual level when reading these results.

Plant vs. Animal Protein
If you eat animal foods, hitting your protein target is straightforward. Plant-based athletes need to be more strategic: combine sources across the day (legumes + grains, for example), prioritize leucine-rich plants like edamame, tempeh, and pumpkin seeds, and target the higher end of the recommended range to account for slightly lower digestibility. Soy is the plant protein most comparable to whey — both score near the top of DIAAS rankings.

Does Excess Protein Harm Healthy Kidneys?
Decades of research in healthy individuals show no evidence that high-protein diets (up to 3g/kg) damage kidney function. The concern stems from misapplied research on patients with pre-existing kidney disease, where protein restriction is sometimes warranted. For healthy people, excess protein is simply converted to glucose via gluconeogenesis or stored as fat — an inefficient process, which is actually one reason high-protein diets support fat loss.