BMR Calculator
The Calories You'd Burn Doing Nothing At All
Basal Metabolic Rate is the energy your body spends just staying alive — keeping your heart beating, your lungs breathing, your cells repairing themselves — if you did nothing but lie still for 24 hours. For most people it accounts for 60–75% of total daily calorie burn, which makes it the anchor figure that every calorie or macro plan is built from.
The Formula
Men: BMR = 10 × Weight(kg) + 6.25 × Height(cm) − 5 × Age + 5
Women: BMR = 10 × Weight(kg) + 6.25 × Height(cm) − 5 × Age − 161
The Mifflin-St Jeor equation, published in 1990, replaced the older Harris-Benedict formula as the more accurate predictor of resting energy expenditure in modern populations, and it's the version used by most dietitians and clinical nutrition software today.
Why BMR Matters
- Building a calorie budget — BMR is the base that gets multiplied by an activity factor to estimate total daily burn (TDEE).
- Spotting an unrealistic diet — eating below your BMR for extended periods can trigger metabolic slowdown and muscle loss rather than healthy fat loss.
- Comparing interventions over time — since BMR shifts with body composition, tracking it (alongside weight) can show whether a training program is preserving or building lean mass.
- Medical and clinical nutrition planning — dietitians use BMR-based equations as the starting point for feeding plans in both weight management and clinical care.
What Moves Your BMR
| Factor | Effect on BMR |
|---|---|
| More lean muscle mass | Increases |
| Increasing age | Decreases |
| Larger body size (taller/heavier) | Increases |
| Prolonged severe calorie restriction | Decreases |
| Male sex (vs. female, same weight/height/age) | Increases |
How to Use This Calculator
- Choose Metric (kg/cm) or Imperial (lb/in) units.
- Select Male or Female.
- Enter your age in years.
- Enter your weight and height.
- Select Calculate to see your estimated BMR in calories per day.
Related Calculations
Turn this resting number into a full daily estimate with the TDEE Calculator, or go straight to a calorie target for your goal with the Calorie Calculator.