BMR Calculator
This BMR calculator finds your basal metabolic rate, the calories your body burns at rest just to keep you running. Enter your age, sex, height, and weight, and you'll get your BMR from the Mifflin-St Jeor formula, with the Harris-Benedict and Katch-McArdle results lined up beside it. It's the foundation your daily calorie needs are built on, in metric or imperial.
- Resting calorie burn
- Three formulas compared
- Mifflin-St Jeor
- Metric or imperial
- Feeds your TDEE
Last updated June 17, 2026 Estimates only, not medical advice Reviewed by the Calcowa team
Enter your age, height, and weight above 0.
For adults. This is a screening estimate, not medical or dietary advice.
These are estimates, not medical advice. Real metabolism varies with muscle, genetics, and more.
BMR formulas side by side
Each formula estimates the same thing a little differently. Mifflin-St Jeor is the modern standard and the headline number here; the others are shown for comparison.
| Formula | BMR | Notes |
|---|
What is BMR?
Your basal metabolic rate is the energy your body uses at complete rest, just to stay alive. It keeps your heart beating, your lungs moving, and your cells working, even while you sleep. For most people it's the biggest part of the calories they burn each day, usually well over half. Everything active you do, from a walk to a workout, stacks on top of this baseline. It's your body just idling. Knowing your BMR is the first step, and it's where every calorie plan begins.
How do you calculate BMR?
The Mifflin-St Jeor equation is the standard. Here's how it goes for a 30-year-old man, 178 cm and 73 kg:
- 1
Multiply your weight10 × 73 kg = 730.
- 2
Add your height term6.25 × 178 cm = 1,112.5, so the running total is 1,842.5.
- 3
Subtract the age term5 × 30 = 150, leaving 1,692.5.
- 4
Add the sex constant+ 5 for men (or − 161 for women) gives about 1,692 calories a day.
From BMR to your daily calories
Your BMR is the resting baseline, but you're rarely at rest all day, so it isn't the number you eat to. Multiply it by an activity factor, from 1.2 if you're sedentary up to 1.9 if you train hard, and you get your total daily energy expenditure. That's the real target. The TDEE calculator does that step and lays out every activity level, while the calorie calculator turns it into targets for losing or gaining. To see where your weight sits, the BMI calculator rounds out the picture.
Frequently asked questions
Is BMR the same as calories burned?
Not quite. BMR is only the resting share, the calories you'd burn doing nothing. Your full daily burn, TDEE, adds movement and exercise on top, so it's always higher than your BMR.
BMR, or basal metabolic rate, is the number of calories your body burns at complete rest just to keep you alive. It powers your heart, lungs, brain, and the rest of your organs around the clock. For most adults it's the largest slice of daily calorie burn, often 60 to 70% of the total. Everything you do on top, from walking to working out, adds to it.
The common way is the Mifflin-St Jeor equation: 10 × weight in kg + 6.25 × height in cm − 5 × age, then + 5 for men or − 161 for women. This calculator runs that, and also shows the Harris-Benedict and Katch-McArdle results so you'll see all three. You just enter your age, sex, height, and weight, and it does the arithmetic in either unit.
They're close cousins. BMR is measured under strict rest, fasted and lying still, while RMR, resting metabolic rate, is measured under slightly looser conditions and usually reads a little higher. In everyday use the two are often treated as the same, and the formulas here estimate your BMR. For planning calories, the small gap rarely matters.
Mifflin-St Jeor is the current go-to and is usually the most accurate for the general population, which is why it's the headline number here. Harris-Benedict is the older standard and reads a touch higher. Katch-McArdle wins for some people, but only when you know your body fat percentage, since it works from lean mass. Use Mifflin-St Jeor if you aren't sure.
Multiply your BMR by an activity factor, from 1.2 if you're sedentary up to 1.9 if you train hard daily. That gives your total daily energy expenditure, and you'll burn that many calories in a day. The TDEE calculator does this step and shows every activity level, and the calorie calculator turns it into weight-loss and gain targets.
A little, slowly. Building muscle nudges BMR up, since muscle burns more at rest than fat does, and crash dieting can push it down as your body conserves energy. Age, sex, and genetics set most of it, so that's where to focus, on your activity and intake, not on trying to hack your metabolism.
Related calculators
More tools for energy and diet.
BMR times your activity level.
Calorie calculatorMaintenance, loss, and gain.
BMI calculatorBody mass index and weight range.
Know your baseline?
Find your BMR above, or browse the full health hub.