Basal Metabolic Rate (BMR) is the number of calories your body requires to maintain basic physiological functions — breathing, circulation, cell production and temperature regulation — while at complete rest. It represents the minimum energy needed to keep you alive. BMR accounts for roughly 60–75% of total daily calorie expenditure for most people.

1. Enter your age, sex, height (cm) and weight (kg).
2. Click Calculate.
3. The result shows your BMR from two widely used equations.

Male, 35 years, 178 cm, 80 kg.
Mifflin-St Jeor: 10×80 + 6.25×178 − 5×35 + 5 = 1,743 kcal/day
Harris-Benedict (revised): 88.362 + 13.397×80 + 4.799×178 − 5.677×35 ≈ 1,816 kcal/day

BMR is not your total daily calorie need — it is the baseline before activity is factored in. To estimate total daily needs, multiply BMR by an activity factor (see the TDEE Calculator). The two equations typically produce similar results; Mifflin-St Jeor is generally considered more accurate for modern populations.

• Confusing BMR with TDEE — BMR is at-rest calories only.
• Treating the result as exact — it is a statistical estimate with individual variation.

Which equation should I use?

The Mifflin-St Jeor equation is generally recommended as the more accurate of the two for most people. The Harris-Benedict equation (revised) is also widely used and shown here for comparison.

Does BMR change over time?

Yes. BMR decreases with age, partly due to loss of muscle mass. It also changes with significant weight changes. Recalculate periodically if your weight or age changes significantly.

How is BMR different from RMR?

Resting Metabolic Rate (RMR) is measured under less strict conditions than BMR and is typically 10–20% higher. Most online calculators, including this one, calculate BMR using the standard equations.