BMR Calculator
Find out your Basal Metabolic Rate - the calories your body burns at complete rest just to stay alive. This free BMR calculator uses the Mifflin-St Jeor equation, the clinical standard, based on your age, gender, height, and weight.
Your BMR is the energy your body spends just to keep you alive - powering your heart, lungs, brain, and every organ even if you stayed in bed all day. It is the largest single chunk of your daily calorie burn, typically 60-75% of the total, which is why understanding it matters far more than most people realise. Knowing your BMR tells you the absolute calorie floor you should not drop below, and it is the number every weight-loss, maintenance, or muscle-gain target is built on top of.
Enter your gender, age, height, and weight above to get your BMR. Below the calculator you will find the exact Mifflin-St Jeor formula, how to read your result, what raises or lowers your BMR, and how to turn it into a real-world calorie target using your TDEE.
Your Basal Metabolic Rate
Calories your body burns at complete rest to keep breathing, circulating blood, and keeping your organs working — before any activity.
Estimated TDEE range
1596–2527
kcal/day depending on activity
Formula used
Mifflin-St Jeor
the current clinical standard
How it works
1
Enter your stats
Add your gender, age, height, and weight. Switch between metric and imperial units anytime.
2
We run the formula
The Mifflin-St Jeor equation calculates the energy your body needs at complete rest.
3
Plan from your BMR
Use your BMR as the floor and your TDEE to set realistic weight-loss or muscle-gain targets.
How BMR is calculated
This calculator uses the Mifflin-St Jeor equation, the resting-energy formula the Academy of Nutrition and Dietetics recommends as the most accurate for the general population. It estimates the calories your body needs at complete rest from four inputs - weight, height, age, and sex - with sex handled by a small constant added for men or subtracted for women.
Mifflin-St Jeor equation
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161
Worked example: a 30-year-old man weighing 80 kg at 178 cm has a BMR of (10 × 80) + (6.25 × 178) - (5 × 30) + 5 = 800 + 1,112.5 - 150 + 5 = 1,767.5 kcal. That is the energy he would burn lying still for 24 hours. The same formula for a woman swaps the final +5 for -161, reflecting the slightly lower resting energy of the average female body. Every calorie target you build afterward starts from this number.
Understanding your result
Your BMR is not a goal to eat down to - it is a floor. It tells you the minimum calories your body needs to keep its organs running, and most adults land in a predictable range:
| Group | Typical BMR | Main drivers |
|---|---|---|
| Adult women | 1,400 - 1,600 kcal | Size, age, lean mass |
| Adult men | 1,600 - 1,800 kcal | More lean mass, taller |
| Muscular / tall | 1,800 - 2,000+ kcal | Muscle burns more at rest |
| Older adults | Lower end | Lost muscle with age |
There is no single good or bad BMR - a higher one simply means your body is bigger, younger, or more muscular. The number becomes useful when you multiply it by your activity level to get your TDEE, which is the figure you actually eat to. As a rule, never stay below your BMR for long: chronic under-eating slows your resting metabolism and strips muscle, which lowers your BMR further and makes future weight loss harder.
Frequently Asked Questions
What is BMR?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to stay alive - powering breathing, heartbeat, brain activity, and organ function. It accounts for roughly 60-75% of your total daily calorie burn.
How is BMR calculated?
This calculator uses the Mifflin-St Jeor equation, the most accurate formula recommended by dietitians. For men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5. For women: the same formula but minus 161 instead of plus 5.
Should I eat my BMR to lose weight?
No. Eating only your BMR is too low and can slow your metabolism and cause muscle loss. For weight loss, aim for 300-500 calories below your TDEE (Total Daily Energy Expenditure), not your BMR. Use our TDEE calculator to find that target.
What's a good BMR?
There is no single good BMR - it is simply the calories your particular body needs at rest, and a bigger, younger, more muscular person naturally has a higher one. Typical adult values fall around 1,400-1,600 kcal for women and 1,600-1,800 kcal for men, but a tall, muscular man can clear 2,000. A rising BMR (from adding muscle) is a healthy sign; a falling one can signal lost muscle or a slowing metabolism.
What is the difference between BMR and TDEE?
BMR is the calories you burn doing nothing at all - the energy to keep your organs running. TDEE is BMR plus everything you burn through daily movement, exercise, and digesting food. BMR is the floor you should never eat below for long; TDEE is the number you actually use to set weight-loss or gain targets.
What raises your BMR?
Building muscle is the most reliable way to raise BMR, because muscle tissue burns more calories at rest than fat. Other factors that push it up include being younger, taller, male, and having more lean mass; factors that lower it include aging, losing weight quickly, and very low-calorie dieting, which can slow your resting metabolism.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation, used by this calculator, is the one most dietitians and the Academy of Nutrition and Dietetics recommend for the general public - it is more accurate than the older Harris-Benedict formula. It is still an estimate (within about 10%), so confirm against real-world weight change over a few weeks.
Is this BMR calculator free?
Yes - completely free with no sign-up. Your inputs are saved in your browser and encoded in the URL so you can bookmark or share your result. Nothing is sent to a server.
Related tools & guides
TDEE Calculator
Multiplies your BMR by activity to find the calories you actually burn each day.
Macro Calculator
Turns your calorie target into protein, carb, and fat grams.
Protein Calculator
Daily protein target to protect muscle - the main lever for a healthy BMR.
BMI Calculator
Check whether your weight sits in the healthy range for your height.
How to Calculate Macros
Walks from your BMR and TDEE through to a full macro split, step by step.
High-Protein Diet Guide
Why protein preserves the lean mass that keeps your BMR healthy.