Which BMR formula is most accurate?

The Mifflin-St Jeor equation (1990) is considered the most accurate for most non-obese adults, with a margin of error around ±10%. It outperforms the older Harris-Benedict equation in clinical validations.

Does BMR change with age?

Yes. BMR typically decreases by 1–2% per decade after age 20, primarily due to loss of muscle mass. Regular strength training can slow this decline significantly.

Is BMR the same as RMR?

Nearly, but not exactly. RMR (Resting Metabolic Rate) is measured under less strict conditions than BMR. In practice, RMR is about 10–20% higher than true BMR, and most calculators labeled 'BMR' actually compute RMR.

Can I eat only my BMR calories?

No. BMR is the bare minimum for survival at rest. Any physical activity requires additional calories. Eating only your BMR would create a large deficit that risks muscle loss and nutrient deficiencies.

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BMR Calculator

Calculate your Basal Metabolic Rate (BMR) — the number of calories your body burns at complete rest. Uses the Mifflin-St Jeor equation, the most accurate formula for most adults.

Last updated: April 13, 2026

How to Use This Calculator

Enter your sex, age, height, and weight.
Choose your preferred unit system (imperial or metric).
Click Calculate to see your BMR in calories per day.
Use your BMR as the foundation for your TDEE calculation.

Real-World Examples

Male BMR Example

30-year-old male, 180 cm, 80 kg.

Result: BMR = (10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal/day.

Female BMR Example

25-year-old female, 165 cm, 60 kg.

Result: BMR = (10 × 60) + (6.25 × 165) − (5 × 25) − 161 = 600 + 1,031 − 125 − 161 = 1,345 kcal/day.

Common Mistakes to Avoid

Confusing BMR with TDEE — BMR doesn't include any activity, so you cannot use it as your daily calorie target without adjustment.
Using the older Harris-Benedict formula, which is less accurate than Mifflin-St Jeor for most people.
Forgetting that BMR decreases as you lose weight — recalculate every 10–15 lbs of change.
Not accounting for muscle mass — highly muscular individuals may have a higher BMR than the formula predicts.

The Formula

Mifflin-St Jeor Equation — Male: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. Female: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Learn More

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TDEE vs BMR: What's the Difference and Which Should You Use?

BMR is calories at rest. TDEE is calories in a day. Here's when each matters.

April 13, 2026 Health

What Is TDEE and How Do You Calculate It?

TDEE is the total calories you burn per day. Here's how to calculate yours.

April 13, 2026

Frequently Asked Questions

BMR (Basal Metabolic Rate) is the number of calories your body needs to perform basic life-sustaining functions — breathing, circulation, cell production — while at complete rest. It represents your minimum calorie requirement.