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BMR Calculator

Calculate basal metabolic rate using common equations and compare methods.

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Formula

BMR equations estimate resting calorie needs from body metrics.

The tool supports Mifflin, Harris, Katch, and comparison modes.

Worked Example

Input age, sex, weight, and height to estimate resting calories.

What is Basal Metabolic Rate (BMR)

BMR is the number of calories your body burns at complete rest to maintain basic life functions: breathing, circulation, cell production, and temperature regulation. It represents the minimum energy your body needs to survive.
  • Mifflin-St Jeor (1990) is the most commonly recommended equation for healthy adults and is considered the most accurate for most people
  • Harris-Benedict (1919, revised 1984) is the classic formula still widely used in clinical settings
  • Katch-McArdle uses body fat percentage instead of gender, making it more accurate for lean or muscular individuals
  • BMR typically accounts for 60% to 75% of total daily calories. The remainder comes from physical activity and digestion

BMR alone does not tell you how much to eat. Multiply BMR by an activity factor to get your Total Daily Energy Expenditure (TDEE), which is your actual daily calorie need.

You can also calculate changes using our TDEE Calculator, Calorie Calculator, Macro Calculator or Body Fat Calculator.

Frequently Asked Questions

What is BMR?

BMR (Basal Metabolic Rate) is the estimated number of calories your body burns per day at complete rest, just to maintain basic life functions like breathing and circulation.

Which BMR equation should I use?

Mifflin-St Jeor is the most commonly recommended for general use. If you know your body fat percentage, Katch-McArdle may be more accurate. Use the compare mode to see results from all equations.

Does muscle mass affect BMR?

Yes. Muscle tissue burns more calories at rest than fat tissue. This is why the Katch-McArdle equation, which uses body fat percentage, can be more accurate for athletic individuals.

How is BMR different from TDEE?

BMR is calories burned at complete rest. TDEE adds calories burned through daily activity and exercise. TDEE is what you use for diet planning, not BMR alone.

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