BMR Calculator
Basal metabolic rate by Mifflin-St Jeor, revised Harris-Benedict and Katch-McArdle.
What it does
Basal metabolic rate is the energy your body uses at complete rest. It is shown by Mifflin-St Jeor, revised Harris-Benedict and, if you know your body fat, Katch-McArdle.
Where it's used
The starting point for working out daily calorie needs.
How to use it
- Choose sex and enter age.
- Enter weight and height.
- Optional: enter body-fat % for the Katch-McArdle equation.
The formula explained
- Mifflin-St Jeor
- 10W + 6.25H − 5A + 5 (men) or − 161 (women)
- Katch-McArdle
- 370 + 21.6 × lean mass (kg)
- W, H, A
- weight (kg), height (cm), age (years)
Worked example
Inputs:
- Sex: Female
- Age: 35 years
- Units: Metric (kg, cm)
- Weight: 62 kg
- Height: 165 cm
The calculator gives:
- BMR (Mifflin-St Jeor): 1,315 kcal/day
- BMR (Harris-Benedict rev.): 1,381 kcal/day
- Per hour: 54.8 kcal/h
Tips and common mistakes
- BMR is at rest — multiply by an activity factor for daily needs (see Calorie Calculator).
- Mifflin-St Jeor is generally the most accurate for most people.
- Results are estimates; individuals vary.
Questions people ask
What is the Mifflin-St Jeor formula?
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years), then + 5 for men or − 161 for women. For a 35-year-old woman of 62 kg and 165 cm that is 1315 kcal per day.
How do I get from BMR to the calories I need each day?
Multiply BMR by an activity factor: about 1.2 if you sit most of the day, up to about 1.9 for very hard daily exercise. The Calorie Calculator does this for you and shows targets for losing or gaining weight.
Why does BMR go down with age?
People usually lose some muscle as they get older, and muscle burns more energy at rest than fat. The formulas reflect this by taking off about 5 kcal per day for each year of age.
Related Health & Body calculators
Enter your values to get the result with the formula, substituted values and an explanation of each step.