Protein Calculator

How much protein do you actually need each day?

The protein calculator gives you a personalised daily protein target based on your weight, activity level, and goal — whether that's maintaining muscle, gaining size, or losing fat without sacrificing lean mass. Enter your weight, pick your goal, and get a recommended range in grams per day, with the science-backed reason behind the number. Everything runs locally in your browser — no upload, no account, no server.

The short answer: most active people need significantly more protein than the standard 0.8g/kg/day WHO recommendation, which was designed to prevent deficiency in sedentary adults — not to support training, recovery, or body recomposition. The International Society of Sports Nutrition's 2017 position stand pegged the optimal range at 1.4–2.0g/kg for exercising adults, rising to 2.0–2.4g/kg for athletes in a caloric deficit. This calculator uses those ranges as its floor and ceiling.

Goal-specific protein targets — maintenance, muscle gain, fat loss

For maintenance (keeping your current body composition while eating at maintenance calories), 1.2–1.6g/kg/day is usually sufficient. You're not building new tissue aggressively, just replacing what normal cellular turnover breaks down. For muscle gain (eating at a caloric surplus with progressive resistance training), 1.6–2.2g/kg/day is the effective range. Studies show that intakes above 2.2g/kg provide no additional hypertrophy benefit — you're in diminishing returns territory, spending money on protein you'll just excrete.

For fat loss (eating at a caloric deficit), protein needs jump to 2.0–2.4g/kg/day because the body is more likely to burn muscle for fuel when calories are restricted. Higher protein during a cut preserves lean mass, which matters because losing muscle lowers your metabolic rate and makes the deficit harder to sustain. Research also shows that higher protein diets reduce appetite during caloric restriction — making the cut more bearable without willpower battles.

Meal timing — does it matter when you eat your protein?

Total daily protein is the most important variable — getting enough over the course of the day matters more than hitting specific meal timings. That said, distributing protein across 3–5 meals does produce modestly better muscle protein synthesis (MPS) than eating the same total in 1–2 sittings. The reason: MPS is stimulated in a dose-dependent way up to roughly 30–40g of high-quality protein per meal, then plateaus. Eating 160g across four meals of 40g each produces more total MPS than eating 160g in two meals of 80g each — even though the total is the same.

The "anabolic window" (the idea that you must eat protein within 30 minutes of training) is much less important than once thought. A 2013 meta-analysis in the Journal of the International Society of Sports Nutrition found that total daily protein intake matters far more than peri-workout timing for most people. That said, a protein-rich meal within 2 hours of training (either before or after) is sensible and practical.

Best protein sources — animal, plant, and supplements compared

Animal proteins (chicken, eggs, beef, fish, dairy) are "complete" — they contain all nine essential amino acids in adequate amounts and have high biological value. Leucine, which is particularly important for triggering MPS, is abundant in whey, eggs, and meat. Plant proteins (legumes, tofu, tempeh, seitan, edamame) tend to be lower in one or more essential amino acids — most notably lysine (in grains) and methionine (in legumes) — but eating a variety across the day fills those gaps. Rice + beans together provide a complete profile, for example.

Whey protein powder is the most studied supplement for muscle gain, with hundreds of randomised trials confirming its efficacy. It's fast-digesting, high in leucine (around 11% by weight), and convenient. Casein protein (slow-digesting dairy protein) is often used before bed. Plant-based protein powders (pea, rice, hemp blends) are improving and can produce comparable gains to whey when leucine content is matched. Supplements should complement food, not replace it — whole foods bring fibre, micronutrients, and satiety that powders don't.

How this compares to Healthline, Examine, and MyFitnessPal protein tools

Healthline's protein calculator provides a quick estimate using fixed multipliers but doesn't adjust for cutting vs. bulking phases or distinguish sedentary from highly active users precisely. Examine.com has excellent research summaries on protein but no interactive calculator. MyFitnessPal defaults to 20% of calories as protein — a percentage-based approach that underestimates needs for lean, active users in a deficit. Cronometer tracks intake accurately but requires logging meals to give a target, adding friction.

This calculator gives a personalised range in grams per day with the scientific justification, a list of foods to hit that target, and a meal-distribution guide — all without signing up, logging meals, or installing an app. It runs entirely in your browser, so your data stays on your device. For people who want a quick, accurate answer to "how much protein do I need" without committing to a tracking app, this is the fastest path to that answer.

How protein synthesis works at the cellular level

Every gram of dietary protein you eat is broken down into its constituent amino acids — the molecular building blocks of all protein structures in the body. There are 20 standard amino acids, of which 9 are essential: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. "Essential" means the body cannot synthesise them from other compounds — they must come from food. The remaining 11 are non-essential (conditionally essential during illness or extreme stress), meaning the liver can manufacture them given adequate raw materials. When you eat a chicken breast, digestive enzymes hydrolyse the protein into free amino acids and short peptides that are absorbed through the gut wall and delivered to tissues via the bloodstream.

Inside muscle cells, protein synthesis is orchestrated at the ribosome. Ribosomes read messenger RNA (mRNA) — a transcribed copy of the DNA blueprint for a particular protein — and link amino acids together in precise sequence to build a polypeptide chain. That chain then folds into a three-dimensional structure determined by the sequence itself and the chemical environment of the cell. This is why protein denaturation matters: heat, acid, or mechanical force can unfold a protein's 3D shape without breaking its amino acid sequence — the reason egg whites solidify when cooked and milk curdles when acidified. The amino acids are unchanged and still fully digestible; only the architecture collapses.

Muscle protein synthesis (MPS) — the specific process of building new contractile muscle fibers — is regulated in part by the mTOR pathway (mechanistic Target of Rapamycin). mTOR is the master switch for cell growth and protein production: it integrates signals from resistance exercise, the amino acid leucine, and insulin, then activates the ribosomal machinery responsible for translating mRNA into new muscle proteins. Leucine is uniquely potent at activating mTOR compared to other amino acids — which is why leucine content is such a key variable when comparing protein sources. Without the leucine stimulus crossing a threshold of roughly 2–3g per meal, mTOR activation is blunted and the anabolic response is submaximal even if total protein intake is adequate.

The science behind protein recommendations — RDA, research, and real optimal intakes

The widely cited RDA of 0.8g of protein per kilogram of body weight is frequently misunderstood. It represents the minimum required to prevent deficiency in 97.5% of sedentary adults — not the amount that optimises muscle maintenance, recovery, or health in active people. The RDA was set using nitrogen balance studies, a methodology that tends to underestimate true requirements and that does not account for the higher turnover rates seen in people who exercise. Treating 0.8g/kg as a target rather than a floor is a systematic error that affects millions of people who use nutrition apps with factory-default protein settings.

The research picture for active individuals is substantially clearer. A landmark 2011 review by Phillips and Van Loon established the 1.6–2.2g/kg range for muscle hypertrophy. A 2018 systematic review and meta-analysis by Morton et al. — pooling data from 49 randomised controlled trials covering 1,800 participants — found that protein supplementation significantly increased muscle mass and strength, with benefits appearing to plateau around 1.62g/kg/day. The ISSN's most recent position stand (Stokes et al. 2018) endorses 1.4–2.0g/kg for exercising individuals and states that intakes as high as 3.0g/kg are safe and may further support body composition during aggressive caloric restriction.

One nuance that single-number targets obscure is the concept of the anabolic ceiling per meal. Research from Witard et al. (2014) and Moore et al. (2009) found that roughly 20–40g of high-quality protein per meal maximally stimulates MPS in young adults; consuming more in one sitting does not produce a proportionally greater response because mTOR signalling saturates. Older adults experience anabolic resistance — a blunted MPS response per gram of protein — meaning they may need closer to 40g per meal to achieve the same stimulus that 20–25g produces in a 25-year-old. This is one reason the ISSN recommends that people over 65 target the upper end of the protein range and prioritise high-leucine protein sources at each meal.

Protein quality scoring systems — BV, PDCAAS, and DIAAS explained

Not all protein grams are equal, which is why nutrition scientists developed scoring systems to compare sources. Biological Value (BV) measures the proportion of absorbed protein that is actually retained and used by the body — a reflection of how well the amino acid profile matches human requirements. Whey scores 104 (it can exceed 100 because BV is measured relative to egg protein, which was originally set at 100), whole egg scores 100, milk 91, beef 80, soy 74, and wheat 54. BV has largely been replaced by more rigorous metrics but remains useful as a rough quality hierarchy.

The PDCAAS (Protein Digestibility Corrected Amino Acid Score) was the FDA's gold standard from 1993 to 2013. It accounts for both digestibility and essential amino acid completeness, with scores capped at 1.0. Whey, egg, casein, and soy all score 1.0 under PDCAAS — but the cap masks meaningful differences between them. The DIAAS (Digestible Indispensable Amino Acid Score), adopted by the FAO in 2013, is more accurate: it uses ileal digestibility (measured at the end of the small intestine, where absorption actually occurs) rather than fecal digestibility, and it removes the 1.0 ceiling. Under DIAAS, whey protein isolate scores approximately 1.25, reflecting its outstanding amino acid profile; egg scores around 1.13; soy scores 0.9–1.0 depending on processing; and most grain proteins score 0.4–0.7. The DIAAS is now the preferred standard in nutrition research.

The practical implication of protein quality scoring is the distinction between complete and incomplete proteins. Animal proteins (meat, fish, dairy, eggs) provide all nine essential amino acids in proportions that closely match human needs — their DIAAS scores reflect this. Most plant proteins are limiting in at least one essential amino acid: rice is low in lysine, most legumes are low in methionine, and corn is deficient in both lysine and tryptophan. This doesn't make plant protein inferior in practice — eating a variety of plant foods across the day provides all essential amino acids — but it does mean that comparing "30g of protein from lentils" to "30g of protein from chicken" is not an apples-to-apples comparison at the cellular level.

Plant-based protein sources — densities, bioavailability gaps, and how vegans meet their targets

The best plant protein sources by density (dry or as-eaten) are worth knowing precisely. Seitan (wheat gluten) is the most concentrated at roughly 75g protein per 100g dry — but it is not suitable for people with celiac disease or gluten sensitivity, and its DIAAS is low due to lysine deficiency. Nutritional yeast provides around 50g protein per 100g and is one of the few plant foods with a reasonably complete amino acid profile. Hemp seeds deliver 31g/100g with a naturally balanced omega-3:6 ratio. Pumpkin seeds provide 30g/100g. Cooked whole foods rank lower by weight due to water content: tempeh 19g/100g, tofu (firm) 17g/100g, edamame 11g/100g, lentils (cooked) 9g/100g, black beans (cooked) 8.9g/100g, and quinoa (cooked) 4.4g/100g. Quinoa is nutritionally notable because it is one of the few plant sources with a near-complete amino acid profile, but its protein density is modest — you need to eat a lot of it to accumulate meaningful grams.

When comparing protein sources on a per-calorie basis, the picture shifts: chicken breast yields about 9g of protein per 100 calories; eggs provide 6g per 100 calories; firm tofu 11g per 100 calories (due to its low fat content); cooked lentils 7g per 100 calories; and quinoa only 3.5g per 100 calories. This matters for anyone managing total calorie intake alongside protein targets. A vegan eating to gain muscle at 1.8g/kg must plan carefully to hit protein targets without excessive calorie surplus, since many calorie-dense plant foods (nuts, seeds, avocado) are low in protein per calorie.

There is a real bioavailability gap between plant and animal proteins. Plant proteins are generally 70–80% digestible compared to 90–95% for animal proteins, because plant cell walls, fibre, and antinutrients (phytates, tannins, lectins) reduce amino acid absorption. Pea protein concentrate is among the best-performing plant proteins, with a PDCAAS approaching 0.9 and digestibility of around 87% — which is why it appears in most premium plant-based protein powders. Fermentation (as in tempeh) and processing (as in protein isolates) can meaningfully improve digestibility. The practical upshot is that vegans and vegetarians likely benefit from targeting 10–20% higher total protein than omnivores to account for the bioavailability gap — for a 70kg vegan targeting 1.8g/kg, the effective dietary target becomes closer to 2.0–2.1g/kg to deliver the same absorbed amino acids.