BMR Calculator
Estimate basal metabolic rate with the Mifflin–St Jeor equation, then see daily energy needs across five activity levels.
- Category
- Calculators
- Updated
- Cost
- Free · no sign-up
Basal metabolic rate
1,379 kcal
What your body burns at complete rest over 24 hours.
Estimated with the Mifflin–St Jeor equation. Expect a margin of roughly 10% either way.
What basal metabolic rate means
Your basal metabolic rate is the energy your body uses simply staying alive over 24 hours — breathing, circulating blood, maintaining temperature, repairing tissue. For most people it accounts for 60–75% of total daily energy use, which is why it dominates any calorie calculation.
The Mifflin–St Jeor equation
This calculator uses Mifflin–St Jeor, which is generally the most accurate estimate available without measuring body composition:
- Men:
(10 × kg) + (6.25 × cm) − (5 × age) + 5 - Women:
(10 × kg) + (6.25 × cm) − (5 × age) − 161
The older Harris–Benedict equation tends to overestimate by around 5%. Katch–McArdle is more accurate still, but requires a body-fat percentage most people don't have.
From BMR to daily needs
BMR alone isn't actionable — nobody lies still for 24 hours. Multiplying by an activity factor gives total daily energy expenditure:
| Activity level | Multiplier |
|---|---|
| Sedentary | 1.2 |
| Lightly active | 1.375 |
| Moderately active | 1.55 |
| Very active | 1.725 |
| Athlete | 1.9 |
Most people pick a level too high. A desk job with three gym sessions a week is lightly active, not very active.
How much to trust the number
Expect roughly ±10%. Genetics, body composition, thyroid function, medication and recent dieting history all move real metabolic rate around. Use the estimate as a starting point, track for a couple of weeks, then adjust based on what actually happens.
How to use the BMR Calculator
Three steps, no sign-up.
Enter your details
Age, sex, height and weight, in metric or imperial units.
Pick an activity level
Be honest — most people overestimate. Desk job with a few gym sessions is 'lightly active'.
Use the daily total, not the BMR
BMR is what you'd burn lying still all day. The total daily figure is the useful one for planning.