BMR Calculator — Basal Metabolic Rate Calculator
Calculate your Basal Metabolic Rate (BMR) — the calories your body burns at rest. Use the Mifflin-St Jeor or Harris-Benedict equation.
❤️ Health & Fitness
✅ Free
By SwiftCalcTools Editorial Team · Formula verified
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How to Use BMR Calculator
- 1Enter the required values in the input fields above.
- 2Click the Calculate button or results update instantly as you type.
- 3View your results in the output panel below the inputs.
- 4Adjust any values to recalculate instantly.
Frequently Asked Questions
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to sustain life — breathing, circulation, cell repair, and temperature regulation. It represents 60–75% of total calorie expenditure for most people.
The Mifflin-St Jeor equation (1990) is considered the most accurate for the general population, within 10% of measured values. The older Harris-Benedict equation (1919, revised 1984) tends to overestimate by about 5%. For obese individuals, the Katch-McArdle formula (using lean body mass) may be more accurate.
Yes. BMR decreases approximately 1–2% per decade after age 20, primarily due to loss of muscle mass (sarcopenia). This is why weight management becomes harder with age — your body needs fewer calories for the same activities. Resistance training helps preserve muscle and maintain a higher BMR.
BMR is calories burned at rest. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor (1.2 for sedentary up to 1.9 for very active) to account for exercise, daily movement, and digestion. TDEE is the actual number of calories you need to maintain your current weight.