🫀 BMR Calculator
How many calories you burn at rest
Written by Albert Mateos · Founder & Editor
Last reviewed: May 2, 2026
How it works
Calculate your Basal Metabolic Rate (BMR) — the number of calories your body burns at rest. Compare results from three formulas: Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle. Understanding your BMR is the first step to calculating your total daily calorie needs.
How to Use This Calculator
- Enter your age, sex, height, and weight.
- The Mifflin-St Jeor formula calculates your BMR automatically.
- Review the number of calories your body burns at complete rest.
- Multiply BMR by an activity factor to estimate total daily needs.
- Use the result as a baseline for nutrition planning.
Example
Inputs: 35-year-old female, 168 cm, 68 kg.
Result: BMR of 1,420 kcal per day.
What it means: Her body burns 1,420 kcal simply keeping vital organs running at rest. Any movement adds to this baseline.
Tips
- BMR typically accounts for 60-70% of total daily energy expenditure. The rest comes from activity and digestion.
- Mifflin-St Jeor is accurate within about 10% for most adults. Very lean or very heavy individuals may need different equations.
- BMR drops roughly 1-2% per decade after age 20, mostly due to muscle loss. Resistance training partially offsets this decline.
- Never eat below your BMR for extended periods. Doing so triggers metabolic adaptation and often leads to rebound weight gain.
- Two people of the same height and weight can have BMRs differing by 200-300 kcal due to lean mass differences. Resistance training raises yours.
Learn More
Frequently Asked Questions
- What's the difference between BMR and TDEE?
- BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to keep organs functioning. TDEE (Total Daily Energy Expenditure) is BMR multiplied by your activity factor. TDEE is what you should base your calorie intake on.
- Which BMR formula is best?
- Mifflin-St Jeor is the most accurate for most people and is recommended by the Academy of Nutrition and Dietetics. Harris-Benedict tends to overestimate slightly. Katch-McArdle is best if you know your body fat percentage, as it accounts for lean mass.
- Can I increase my BMR?
- Yes. Building muscle is the most effective way — muscle tissue burns more calories at rest than fat. Regular exercise, adequate sleep, and avoiding crash diets also help maintain a healthy metabolic rate.
Authoritative resources
We recommend these external sources for further reading from recognized health organizations and peer-reviewed literature:
Scientific References
This calculator is based on peer-reviewed research and established health guidelines:
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 51(2): 241-247. 1990.
- Harris JA, Benedict FG. A biometric study of basal metabolism in man. Carnegie Institution of Washington, Publication 279. 1919.