BMR — Quick 8‑Section Guide
Use this Basal Metabolic Rate calculator to estimate resting calories with standard formulas. Results are instant and computed in your browser.
1) Core idea
- Mifflin‑St Jeor (default): men 10W + 6.25H − 5A + 5; women 10W + 6.25H − 5A − 161
- Harris‑Benedict (revised): men 13.397W + 4.799H − 5.677A + 88.362; women 9.247W + 3.098H − 4.330A + 447.593
- Katch‑McArdle: 370 + 21.6 × LBM, where LBM = (1 − F) × W (F = body‑fat %/100)
2) Flow
- Enter age, sex, height, weight (units auto‑convert: 1 in = 2.54 cm; 1 lb = 0.45359237 kg)
- Pick a formula (use Katch‑McArdle if you know body‑fat %)
- Get BMR; multiply by activity later to estimate TDEE
3) Sanity checks
- Realistic ranges: age 10–120, height 100–250 cm, weight 30–250 kg
- Katch‑McArdle needs body‑fat between ~5–50%
4) Shortcuts
- Default to Mifflin‑St Jeor for most people
- Know BF%? Try Katch‑McArdle for lean‑mass based BMR
5) Pitfalls
- Using the wrong units (cm vs in, kg vs lb)
- Comparing BMR from different formulas without noting context
6) Micro examples
- MSJ male: 70 kg, 175 cm, 30 y → 10×70 + 6.25×175 − 5×30 + 5 = 1663.8 kcal
- MSJ female: 60 kg, 165 cm, 30 y → 10×60 + 6.25×165 − 5×30 − 161 = 1380.3 kcal
7) Mini‑FAQ
- Which is “best”? MSJ generally; KMA if BF% is known
- Privacy? All math runs locally in your browser
8) Action tip
Use BMR × activity (1.2–1.9) to get TDEE, then adjust ±300–500 kcal to lose/gain weight. Reassess every 2–3 weeks.