BMR Calculator
Calculate your Basal Metabolic Rate and daily energy needs.
All calculations happen locally in your browser — nothing is uploaded, stored or tracked.
Enter your details
Sex, age, height and weight.
Read the BMR estimates
From three well-known equations.
Check daily needs
BMR × activity factor for maintenance calories.
What Is BMR?
Your Basal Metabolic Rate is the number of calories your body burns at complete rest — keeping your heart beating, lungs breathing, brain working and body warm. It typically makes up 60–75% of total daily energy use.
The calculator applies three established equations — Mifflin-St Jeor, Harris-Benedict and the revised Harris-Benedict — so you can compare estimates. It then scales your BMR by an activity factor to estimate daily maintenance calories.
The Formulas
Where w is weight in kg, h height in cm, a age in years. All are population estimates — individual variation is normal and can be 10% or more.
Your data never leaves your device.
Every calculation on this site runs in your browser using vanilla JavaScript. Nothing is uploaded, stored or tracked.
- 100% local, client-side calculations
- No data stored on any server
- No tracking, no analytics, no ads scripts
- Works offline once loaded
Frequently Asked Questions
What is BMR vs TDEE?
BMR is energy burned at complete rest. TDEE adds activity and is what you need to maintain weight.
Which BMR formula is most accurate?
Mifflin-St Jeor is generally considered the best for most adults; the others are shown for comparison.
How many calories do I burn at rest?
Most adults burn roughly 1,200–1,900 kcal per day at rest depending on age, sex, height and weight — the calculator gives your specific estimate.
Can I lose weight by eating below BMR?
Eating below BMR is generally too aggressive and unsustainable. Use the calorie calculator for sensible targets.
Does muscle increase BMR?
Yes — muscle tissue burns more calories at rest than fat, which is one reason strength training supports a higher metabolism.