BMR Calculator
Calculate Basal Metabolic Rate using Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas.
Your measurements
Updates as you typeBMR across ages
The dot shows your current BMR. Holding everything else constant, this is how it shifts as the selected variable changes.
BMI categories
Your row is highlighted| Category | BMI range | Weight at your height |
|---|---|---|
| Underweight | < 18.5 | — |
| Normal | 18.5 – 24.9 | — |
| Overweight | 25 – 29.9 | — |
| Obese | ≥ 30 | — |
Formula
- kg
- Body weight in kilograms
- cm
- Height in centimetres
- age
- Age in years
- s
- Sex constant: +5 for male, −161 for female
- Weight = —
- Height = —
- Age = —
- Formula = Mifflin-St Jeor
- Plugged in: —
- BMR = —
- × activity — → TDEE = —
Mifflin-St Jeor is the default for a general population. Harris-Benedict (1984 revision) tends to read slightly higher, and Katch-McArdle replaces the whole term with lean body mass derived from body-fat %. Activity multipliers convert BMR into TDEE — the total calories you burn on an average day.
How It Works
BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest to maintain vital functions like breathing and circulation.
The Mifflin-St Jeor equation (1990) is considered the most accurate for most people. The Katch-McArdle formula uses lean body mass and requires body fat percentage input.
Tips & Best Practices
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR is the calories your body burns at complete rest. TDEE (Total Daily Energy Expenditure) includes BMR plus calories burned through physical activity and the thermic effect of food. TDEE is always higher than BMR.
Why do the formulas give different results?
Each formula was developed using different study populations and methodologies. Mifflin-St Jeor uses weight, height, age, and gender. Katch-McArdle uses lean body mass, which accounts for body composition differences.