Example 1 — Man, age 30
- Weight: 80 kg
- Height: 180 cm
BMR ≈ 1780 kcal/day
A typical result for an active man of average weight and height.
BMR calculator — basal metabolic rate
Enter sex, age, weight, and height — see how many calories you burn at complete rest (Mifflin–St Jeor).
This is a table-based estimate, not a lab measurement or a meal plan. Real metabolism also depends on muscle, genetics, and health — ask a doctor or dietitian if you're unsure.
Result
Fill in the fields and click Calculate.
How results are calculated
Mifflin–St Jeor: 10×weight(kg) + 6.25×height(cm) − 5×age, then +5 for men or −161 for women.
Mifflin–St Jeor uses kg and cm internally. Enter weight (lb) and height (in) from the header — we convert, then: 10×kg + 6.25×cm − 5×age (+5 / −161).
Result in kcal/day — energy for vital functions at rest, not including activity.
For total daily needs (TDEE), multiply BMR by an activity factor in the TDEE calculator.
How to use the calculator
- Choose your sex.
- Enter your age in years.
- Enter your weight in the header unit (kg or lb).
- Enter your height (cm or inches).
- Click Calculate to see your BMR in kcal/day.
Usage examples
Example 2 — Woman, age 28
- Weight: 65 kg
- Height: 165 cm
BMR ≈ 1380 kcal/day
The difference versus the man's result comes from the −161 constant.
Example 3 — Man, age 45
- Weight: 95 kg
- Height: 175 cm
BMR ≈ 1824 kcal/day
Higher weight raises BMR even though the older age lowers it.
FAQ
Why bother knowing my BMR?
BMR is the calories you burn at complete rest — breathing, circulation, basics. It's the floor for figuring out full-day needs (TDEE).
Why Mifflin–St Jeor specifically?
It's one of the most recommended BMR formulas: sex, age, weight, height. For most adults it lands closer than older Harris–Benedict.
Is BMR the same as what I should eat daily?
No. BMR is rest with no movement. For real daily needs you multiply by activity — that's the TDEE calculator.
Why do men and women get different results?
At the same weight and height, men usually carry more muscle and women more fat, so metabolism runs lower — hence −161 for women and +5 for men.
Does age really lower BMR?
Yes — the formula subtracts 5 kcal per year. Metabolism usually drifts down with age, mostly from muscle loss.
How much can I trust this number?
It's a solid population estimate, but your metabolism also depends on muscle, genetics, and health. Use it as a start, not a verdict.
What do I do with the result?
Most people treat it as a calorie floor (staying under BMR for long usually isn't wise) and as the base for TDEE.
Kids or pregnancy?
Mifflin–St Jeor is for adults. Pregnancy, breastfeeding, and children need different rules — ask a doctor or dietitian.