BMR Calculator
Calculate your Basal Metabolic Rate using the Mifflin-St Jeor equation — the calories your body burns at rest per day — plus estimated TDEE across all activity levels.
Uses the Mifflin-St Jeor equation — considered the most accurate BMR formula for most adults.
Basal Metabolic Rate
Fill in all fields above to see your BMR.
About BMR Calculator
The BMR Calculator estimates your Basal Metabolic Rate — the calories your body burns at complete rest just to keep your heart, lungs, brain and organs running. It uses the Mifflin-St Jeor equation, which most dietitians consider the most accurate formula for the general population.
BMR is the foundation for any calorie target: everything you burn through movement and digestion is added on top of this baseline number. The formula combines age, height, weight and biological sex to estimate a population-average resting requirement.
Because it is an estimate rather than indirect calorimetry, the number is best used as a planning baseline. Changes in lean mass, illness, medication, hormones and prolonged dieting may make an individual result differ.
How BMR Calculator works in practice
- 1Choose your unit system: metric (cm/kg) or imperial (ft-in/lb).
- 2Enter your age, biological sex, height and weight.
- 3Read your estimated BMR in calories per day.
- 4Use the result as a starting point for the Calorie Calculator to find your full daily energy needs.
Jobs this tool is built for
- Establish a resting-calorie baseline before estimating total daily energy expenditure.
- Compare how a change in body weight affects an estimated calorie requirement.
- Provide a transparent starting estimate for a nutrition discussion with a dietitian.
- Avoid confusing resting needs with the higher calorie burn of an active day.
What you can do here
- Mifflin-St Jeor equation (the current clinical standard)
- Metric and imperial input
- Instant recalculation on every change
- Pairs directly with the Calorie/TDEE Calculator
Limits and honest caveats
- BMR assumes a person lying still all day — it is not the number of calories you should eat. Add activity level to get a realistic target.
- The formula is a population average; individual metabolism varies with muscle mass, genetics, thyroid function and other factors a calculator cannot measure.
- For most healthy adults, BMR accounts for roughly 60–75% of total daily energy expenditure — the rest comes from movement and digestion.
Common questions about BMR Calculator
How is BMR calculated?
Mifflin-St Jeor: for men, (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women, subtract 161 instead of adding 5.
Why does the formula ask for biological sex?
Men typically carry more lean muscle mass than women at the same height and weight, and muscle burns more calories at rest than fat — the formula adjusts for that average difference.
Is this the same as TDEE?
No — BMR is the resting baseline. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to estimate real daily burn.
Can I eat below my estimated BMR?
BMR is not a personal minimum prescription, but sustained aggressive restriction can carry health risks. Use a moderate TDEE-based plan and seek professional advice for significant weight loss.
This page was written by the ToolSink team to explain how BMR Calculator works on this site — it is not syndicated, scraped, or spun from another publisher. How we write tool guides · Site updates · About ToolSink.
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