What is bmr calculator?
Basal metabolic rate is the number of calories your body uses at complete rest to keep you alive, including breathing, circulation and cell repair. It is usually the largest part of daily energy use.
Multiplying the rate by an activity factor gives an estimate of the calories you burn in a normal day.
How to use the bmr calculator
- Choose your sex and units.
- Enter your age, height and weight.
- Read your BMR and the daily calories for each activity level.
How the bmr calculator works
The Mifflin St Jeor equation is used. BMR = 10 times weight in kg plus 6.25 times height in cm minus 5 times age, then plus 5 for men or minus 161 for women. Activity factors are 1.2, 1.375, 1.55, 1.725 and 1.9.
Worked example
Common uses of the bmr calculator
- Starting a nutrition plan.
- Understanding daily energy needs.
- Setting a calorie target for weight changes.
- Comparing activity levels.
- Fitness coaching.
Tips and common mistakes
Treat the result as a starting point and adjust after a few weeks of tracking.
Very low calorie plans can be unsafe. Speak to a doctor or dietitian first.
Background: what to know before you rely on it
Metabolic rate depends mainly on lean body mass, which is why larger and more muscular people burn more at rest. It falls slowly with age. The Mifflin St Jeor equation was published in 1990 and replaced the older Harris Benedict formula in many clinics because it matched measured results better. Equations like this are averages for groups and can be off by a few hundred calories for an individual, so a calculator is a place to start and not a prescription.
Private, free and fast
This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all calculators, or browse the full list of tools.
Frequently asked questions
What is a good BMR?
It varies by body size, age and sex. There is no single good number.
Which formula is best?
Mifflin St Jeor is widely used and tends to be accurate for most adults.
Is BMR the same as TDEE?
No. TDEE includes activity, BMR does not.
Is this medical advice?
No. It is an estimate for general information.
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