What is the BMR Calculator?
Estimate your basal metabolic rate (BMR) — calories burned at complete rest — using Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle formulas. Compare all equations side by side and see TDEE maintenance estimates for five activity levels. Metric or imperial units. Free, private, and instant in your browser.
How to use the BMR Calculator
- Choose metric or imperial units and enter sex, age, weight, and height.
- Optionally add body fat % for Katch-McArdle.
- Select your preferred primary BMR formula.
- Review BMR across all formulas and TDEE activity estimates.
- Copy results or use the Calorie Calculator for weight goals and macros.
Common use cases
- Finding resting calorie needs before setting a diet plan
- Comparing BMR formulas for a nutrition coaching client
- Estimating maintenance calories at different activity levels
Frequently asked questions
- What is BMR?
- Basal metabolic rate is the energy (in kcal/day) your body needs to maintain basic functions at rest — breathing, circulation, cell repair — before activity or digestion.
- Which BMR formula is most accurate?
- Mifflin-St Jeor is widely used and often more accurate than older Harris-Benedict equations. Katch-McArdle can be better when you know body fat % and lean mass.
- What is the difference between BMR and TDEE?
- BMR is rest-only calories. TDEE (total daily energy expenditure) multiplies BMR by an activity factor to estimate maintenance calories including movement and exercise.
- Do I need body fat percentage?
- Only for Katch-McArdle. Other formulas use sex, age, weight, and height only.
- Is my data uploaded?
- No. All calculations run locally in your browser.
