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Nutrition As of 2026-04-24

How Protein Intake Calculator works

Methodology for the Protein Intake Calculator: formulas, coefficients, data sources, assumptions, and known limitations.

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Education · Not medical advice. Output is deterministic math from your inputs.Editorial standardsSponsor disclosureCorrections

Scope

Reports a daily protein target in grams based on bodyweight and goal (general health, hypertrophy, fat loss, older adult).

Formula

protein_target_g = bodyweight_kg x multiplier_for_goal.

Coefficients

Parameter Value Note
General health 0.8–1.2 g/kg/day
Hypertrophy 1.6–2.2 g/kg/day
Fat loss (preserve LBM) 2.2–2.6 g/kg/day
Older adult (sarcopenia prevention) 1.2–1.6 g/kg/day

Data sources

  1. Morton RW, Murphy KT, McKellar SR, et al. 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. Br J Sports Med. 2018;52(6):376-384. — PMID 28698222. Supports the 1.6–2.2 g/kg/day hypertrophy range.
  2. Phillips SM, Chevalier S, Leidy HJ. Protein 'requirements' beyond the RDA: implications for optimizing health. Appl Physiol Nutr Metab. 2016;41(5):565-572. — PMID 26960445.
  3. Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542-559. — PMID 23867520. Source of the sarcopenia-prevention range.
  4. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. — PMID 28642676. ISSN consensus on protein intake for active adults.

Assumptions

  • Protein is distributed across 3–5 meals; total per day is the metric that matters.

Approximation range

Hypertrophy response plateaus above ~1.6 g/kg/day; diminishing returns above 2.2 g/kg/day in non-deficit conditions.

Limitations

  • Does not adjust for kidney disease — people with CKD should follow clinical guidance, not this tool.
  • High-protein intakes are safe for healthy adults per current evidence, but the tool cannot see medical history.

Reproducibility

Hypertrophy, 85 kg: 85 * 1.6 = 136 g; 85 * 2.2 = 187 g. Range 136–187 g/day.

Change log

  • 2026-04-24: methodology page first published.
  • TDEE Calculator — Estimate your daily energy expenditure with Mifflin-St Jeor + activity factors.
  • BMR Calculator — Estimate basal metabolic rate and maintenance calories using Mifflin-St Jeor assumptions.
  • Macro Calculator — Convert calorie targets into protein, carbs, and fat grams for your goal.
  • Water Intake Calculator — Calculate daily water intake based on weight, activity level, and climate.

Worked example

Computed by the same engine bundle served at /engines/protein-intake-calculator.js. Re-runnable: the values below are the literal output of compute(engineInput).

Input

tool
protein_intake_calculator
weight_kg
80
activity_level
active
goal
bulk

Output

minGrams
136
maxGrams
168
targetGrams
152
perKg
{"min":1.7000000000000002,"max":2.1,"target":1.9000000000000001}
perMeal
38
mealsPerDay
4
evidenceRanges
[{"source":"RDA Minimum","minPerKg":0.8,"maxPerKg":0.8,"citation":"Institute of Medicine, DRI 2005"},{"source":"ISSN Position Stand","minPerKg":1.4,"maxPerKg":2,"citation":"Jäger et al. (2017), J Int Soc Sports Nutr"},{"source":"Meta-analysis (cutting)","minPerKg":2.3,"maxPerKg":3.1,"citation":"Helms et al. (2014), Int J Sport Nutr Exerc Metab"},{"source":"Muscle protein synthesis ceiling","minPerKg":1.6,"maxPerKg":2.2,"citation":"Morton et al. (2018), Br J Sports Med"}]
plantBasedAdjustment
false
coachSummary
For muscle gain at 80 kg, aim for 152g protein per day (1.7–2.1g per kg). That's ~38g per meal across 4 meals — roughly a palm-sized portion of meat/fish or a scoop of protein per meal. The leucine threshold (~2.5g per meal) matters for muscle protein synthesis — whey, eggs, and meat hit it easily; plant sources may need combining.

FAQ

Which formula is used here?
Uses grams-per-kilogram evidence ranges adjusted by activity level and goal.
Can I use metric or imperial units?
Yes. This tool supports both metric and imperial units and remembers your preference.
Is this medical advice?
No. This tool provides general fitness estimates and should not replace medical guidance.
Is this tool free and private to use?
Yes. AI Fit Hub tools are free, no-signup browser tools. Inputs stay in your browser unless you choose to share a URL.
Do these tools replace medical guidance?
No. These outputs are general fitness estimates — not medical advice.
Can I switch between metric and imperial units?
Yes. Every tool supports both systems and remembers your preference in localStorage.
General fitness estimates — not medical advice. Consult a healthcare professional for medical decisions.