Know your body's metabolic blueprint.
A free calorie estimator built on the widely-used Mifflin-St Jeor equation for healthy adults. Your BMR, maintenance and weight targets — in one tap.
Biometric Input
Mifflin-St Jeor equation
Awaiting your metrics
Enter your details and hit Calculate to reveal your biometric summary.
More calculators from Mifflin St Jeor
TDEE Calculator
Find your Total Daily Energy Expenditure — BMR plus activity — for weight loss, maintenance, or muscle gain.
Body Fat % Calculator
Estimate your body fat percentage from a tape measure using the US Navy circumference method.
Calorie Deficit Calculator
Get a safe, sustainable daily calorie target for weight loss or gain based on your TDEE.
Macro Calculator
Split your daily calories into protein, carbs, and fat grams based on your goal.
Protein Calculator
Get your daily protein target in grams, based on your weight and goal.
Ideal Body Weight Calculator
Compare Devine, Robinson, Miller, and Hamwi formulas side by side from your height.
Lean Body Mass Calculator
Get your lean mass, fat mass, and Katch-McArdle BMR from weight and body fat %.
What Is BMR, and Why Does It Matter?
Your basal metabolic rate (BMR) is the number of calories your body burns each day just to stay alive, before you take a single step. It covers your heart beating, your lungs breathing, and your cells repairing themselves around the clock.
BMR typically makes up 60 to 75% of the calories you burn in a day, making it the single biggest piece of your energy budget. Knowing it gives you a real starting point for weight loss, muscle gain, or maintaining your current weight.
The Formula This Calculator Uses
This tool runs the Mifflin-St Jeor equation, the formula most dietitians recommend for healthy adults:
| Formula | |
|---|---|
| Men | (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5 |
| Women | (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161 |
Once you have your BMR, multiplying it by an activity level gives you your Total Daily Energy Expenditure (TDEE), the number that actually reflects how many calories you burn in a full day.
Where to Go From Here
Want the full breakdown, including how BMR differs from RMR and REE, a worked example, and what actually affects your number? Read our complete guide to BMR.
If you're deciding whether to use BMR or TDEE for your calorie target, see BMR vs. TDEE explained. For the formula's full history and how accurate it is, read what the Mifflin-St Jeor equation actually is.
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