BMR calculator

Your basal metabolic rate (BMR) is the energy your body needs just to stay alive at rest: breathing, circulation and keeping warm.

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If you know it, we'll also use the Katch-McArdle formula, which accounts for muscle mass.

Your BMR
1,780 kcal/day
Mifflin-St Jeor formula

This is what you'd burn lying still all day. Your real daily needs are higher: see your TDEE.

Mifflin-St Jeor
1,780 kcal
Harris-Benedict (revised)
1,870 kcal
Katch-McArdle
Add body fat
Estimated daily calories (BMR × activity)
Activity levelCalories per day
Sedentary2,140 kcal
Lightly active2,450 kcal
Moderately active2,760 kcal
Very active3,080 kcal
Extra active3,390 kcal

What is BMR?

Basal metabolic rate is the minimum energy your body needs to function at rest: keeping your heart beating, lungs breathing, brain working and body temperature stable. For most people it's 60–70% of the calories they burn in a day.

The formulas compared

  • Mifflin-St Jeor (1990) is the most accurate for most adults and is what dietitians use by default.
  • Harris-Benedict (revised 1984) is the older standard and tends to run slightly higher.
  • Katch-McArdle uses lean body mass, so it's best if you know your body fat, especially if you're very muscular.

What affects BMR?

Bigger bodies and more muscle mean a higher BMR. It declines slowly with age, mostly because of muscle loss, and is typically lower in women for the same weight because of differences in body composition. Strength training is the most reliable way to keep it up.

Frequently asked questions

What's the difference between BMR and RMR?
BMR is measured under strict lab conditions (fasted, fully rested); resting metabolic rate (RMR) is measured more loosely and comes out slightly higher. In practice the formulas estimate both, and the difference is small.
Should I eat my BMR to lose weight?
Not usually. Eating only your BMR ignores everything you burn by moving. A deficit from your TDEE is a safer, more sustainable approach.
Can I increase my BMR?
Building muscle raises it modestly. Crash dieting lowers it, so slower weight loss with plenty of protein and strength training helps protect it.

These results are estimates for healthy adults and are not medical advice. If you are pregnant, breastfeeding, under 18, or managing a medical condition, talk to your doctor or a registered dietitian.

Related calculators

TDEE calculator
How many calories you burn per day, including exercise.
Maintenance calories calculator
How many calories you need to keep your weight the same.
Lean body mass calculator
Estimate lean body mass from height and weight, or from body fat.