Protein calculator
The protein calculator returns a daily protein target in grams based on your body weight, activity level, and goal (lose fat, maintain, build muscle). Protein needs scale with body mass and physical demands; the formula uses grams-per-kilogram-of-body-weight ranges drawn from sports-nutrition consensus (ISSN, ACSM, Mayo Clinic).
Formula
target_g = body_weight_kg × protein_per_kg
Where protein_per_kg comes from this lookup:
| Activity level | Lose fat | Maintain | Build muscle |
|---|---|---|---|
| Sedentary | 1.2 g/kg | 0.8 g/kg | 1.2 g/kg |
| Moderate | 1.6 g/kg | 1.2 g/kg | 1.6 g/kg |
| Athlete | 2.0 g/kg | 1.6 g/kg | 2.2 g/kg |
The 0.8 g/kg maintenance floor for sedentary adults is the WHO / US RDA (Recommended Dietary Allowance) — the minimum to prevent deficiency, not an optimum. Athletes and people in caloric deficit need more.
Sources for the higher ranges:
- Helms et al., International Journal of Sport Nutrition and Exercise Metabolism, 2014 — recommends 2.3–3.1 g/kg of fat-free mass during cuts for lean athletes.
- Phillips et al., Journal of Sports Sciences, 2011 — 1.6–2.2 g/kg for muscle protein synthesis maximisation during resistance training.
- ISSN Position Stand on Protein and Exercise (2017) — 1.4–2.0 g/kg/day for general resistance training, with higher (up to 2.4 g/kg) for athletes in energy deficit.
- Bauer et al., PROT-AGE Study Group (2013) — recommends 1.0–1.2 g/kg for older adults to preserve muscle mass.
Inputs
| Field | Notes |
|---|---|
| Body weight | kg or lb |
| Activity level | Sedentary / moderate / athlete |
| Goal | Lose fat / maintain / build muscle |
Output
The page returns:
- Daily protein target in grams.
- g/kg used (the multiplier from the table).
- Approximate calories from protein (g × 4 kcal/g).
- Per-meal target if you specify a meal count.
Worked example
A 70-kg person, moderately active, trying to lose fat:
target = 70 × 1.6 = 112 g/day
calories from protein = 112 × 4 = 448 kcal
So 112 g protein / day, contributing ~448 kcal toward the daily total.
For the same person trying to build muscle as an athlete:
target = 70 × 2.2 = 154 g/day → 616 kcal
154 g protein / day. Split across 4 meals: ~39 g per meal.
Why protein matters
- Muscle protein synthesis — strength training stimulates protein synthesis; adequate dietary protein supports the response. The Phillips/Helms work cited above shows higher protein intakes (1.6–2.2 g/kg) maximize the response compared to the RDA floor.
- Satiety — protein has the highest thermic effect of food (~25% of intake is burned in digestion) and increases satiety per calorie. Higher-protein diets show better adherence during caloric deficits in published trials.
- Muscle preservation in a deficit — when you're cutting calories, higher protein intake reduces the proportion of weight lost from muscle vs fat.
- Aging — sarcopenia (age-related muscle loss) is mitigated by protein intakes above the RDA (PROT-AGE recommends 1.0–1.2 g/kg minimum for adults over 65).
Considerations
- Lean-body-mass based targets are arguably more accurate. If you know your LBM (from DEXA or similar), 1.8–2.7 g/kg of LBM is a common range across training contexts. LifeWell's calculator uses total body weight because most users don't have LBM data.
- Very obese individuals may overshoot protein needs using total body weight; targeting goal weight (or LBM) rather than current weight is a common adjustment.
- Plant-based diets can hit these targets but require more attention to protein-rich foods (legumes, tofu, tempeh, seitan, protein powders). Animal-based diets typically reach targets with less planning.
- Per-meal distribution of 0.4 g/kg per meal across 3–5 meals is suggested by the leucine-threshold literature (Schoenfeld & Aragon, JISSN, 2018) for maximising synthesis.
Renal-function caveat
For most healthy people with normal kidney function, protein intakes up to 2.0–2.5 g/kg show no adverse effect on renal markers in published studies (Devries et al., Journal of Nutrition, 2018). The "high-protein is hard on kidneys" myth comes from extrapolating findings in chronic kidney disease (where protein restriction is prescribed) to healthy individuals (where it's not warranted).
If you have CKD, diabetic nephropathy, or other clinical kidney concerns, follow your clinician's protein guidance — not this calculator's.
Limits
- No body composition input. Two people of the same weight can have very different lean mass and very different real protein needs.
- Doesn't distinguish protein quality. 100 g of chicken breast protein is not exactly equivalent to 100 g of gelatin protein. The targets assume normal-diet protein quality.
- Doesn't model age × hormonal state. Postmenopausal women and older men have different anabolic responses to protein than young trainees; the table simplifies.
Frequently asked
Is 2 g/kg too much? For healthy adults with normal kidney function, no — the literature consistently shows safety up to 2.5–3 g/kg in trained populations. For most people the issue is reaching the target, not avoiding overshoot.
Does timing of protein matter? Distribution across the day matters more than precise timing around workouts. Aim for 3–5 protein-rich meals/snacks with ~0.4 g/kg per meal. The "post-workout protein window" turns out to be much wider than the old 30-minute rule.
What counts as "athlete"? The "athlete" tier is for people training resistance and/or endurance most days of the week at meaningful intensity — competitive athletes, dedicated lifters, or training-focused recreational athletes. If you train 2–4 times a week at moderate intensity, "moderate" is the right tier.
Can I save this target? The calculator is stateless. Take a screenshot. The Nutrition and diet module can log daily protein in the meal-notes field.
My doctor told me to limit protein. Follow your doctor. Protein-restriction is prescribed for CKD and a few rarer conditions. The calculator's recommendations are for healthy adults.
Where to read next
- Macro calculator — full macro split.
- Calorie calculator — daily calorie target for goal.
- TDEE calculator — maintenance base.
- Exercise and workouts — training context for protein need.
Last updated: 2026-05-11 Author: Ahsan Mahmood
:::note Health information — not medical advice LifeWell and this documentation are provided for general wellness and educational purposes only. They are not a substitute for professional medical advice, diagnosis, or treatment, and nothing here is intended to diagnose, treat, cure, or prevent any condition. Always consult a qualified healthcare professional with questions about your health, and never disregard or delay professional advice because of something you read here. In an emergency, contact your local emergency services. :::