BMR Calculator (Mifflin-St Jeor)
Your Basal Metabolic Rate (BMR) is the energy your body uses just to stay alive at complete rest — breathing, circulating blood, keeping cells working. It is the largest share of most people’s daily calorie burn, and it is the baseline for any weight-management plan.
This calculator uses the Mifflin-St Jeor equation, the most widely recommended modern formula. Enter your sex, age, height and weight to see your BMR in calories.
It is the baseline for any weight-management plan — the number your daily targets are built on top of once activity is added.
Enter your values to see the result.
How this is calculated
Basal Metabolic Rate (BMR) is the energy your body uses just to stay alive at complete rest — breathing, circulating blood, maintaining temperature, keeping cells working. It is the largest share of most people’s daily calorie burn. This calculator uses the Mifflin-St Jeor equation, the most widely recommended modern formula: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women, the same expression but − 161 instead of + 5.
The equation estimates BMR from sex, age, height and weight. It is more accurate than older formulas (such as Harris-Benedict) for modern populations, but it is still an estimate — real BMR varies with muscle mass, genetics, hormones and health status.
The model gives rest-only energy; it does not include the thermic effect of food, any activity, or the extra burn from illness or recovery. It does not account for body composition (muscle raises BMR, fat lowers it relative to weight), pregnancy, or metabolic conditions. To estimate your full daily burn including activity, use the TDEE calculator, which multiplies this BMR by an activity factor.
Worked example
A 30-year-old man, 175 cm tall, weighing 70 kg.
- 110 × weight = 10 × 70 = 700.
- 26.25 × height = 6.25 × 175 = 1,093.75.
- 3BMR = 700 + 1,093.75 − (5 × 30) + 5 = 1,648.75 ≈ 1,649 kcal/day.
Frequently asked questions
- What is the Mifflin-St Jeor equation?
- For men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5. For women: the same, but − 161 instead of + 5. It is more accurate than older formulas for modern populations.
- Why is my BMR lower than I expected?
- BMR falls with age and with lower body weight. Muscle also raises BMR, so strength training can modestly increase the calories you burn at rest.
- How is BMR different from TDEE?
- BMR is rest-only energy. TDEE multiplies BMR by an activity factor to estimate total daily burn. Use the TDEE calculator to include activity.
- What is the Mifflin-St Jeor equation?
- For men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5. For women: the same, but − 161 instead of + 5. It is more accurate than older formulas for modern populations.
- How is BMR different from TDEE?
- BMR is rest-only energy. TDEE multiplies BMR by an activity factor to estimate total daily burn. Use the TDEE calculator to include activity and set maintenance or loss targets.
Related calculators
Method: Mifflin-St Jeor equation. No external data source. Last updated: September 2026.
These results are general estimates from established formulas and are not medical advice. They depend on the accuracy of the values you enter and on individual factors the formulas cannot capture. Consult a qualified healthcare professional before making decisions about your diet, training or treatment.