BMR Calculator
What is BMR?
Basal Metabolic Rate (BMR) is the amount of energy your body needs at rest to run essential functions like breathing, circulation, and cell repair. Knowing your BMR helps you estimate daily calorie needs and plan nutrition more precisely.
BMR is an estimate and can vary by genetics, hormones, and body composition.
How the calculator works
- Select Male or Female.
- Choose Metric or Imperial units.
- Enter your age, height, and weight in the shown fields.
- Click Calculate to get your BMR (kcal/day) using the Mifflin–St Jeor equation.
- Use Copy or Share to keep your result for later.
Inputs & Units
- Age: in years.
- Height: Metric (cm) or Imperial (ft + in).
- Weight: Metric (kg) or Imperial (lb).
- Only the fields for your selected unit are shown to prevent mistakes.
Tip: Measure height without shoes and weigh yourself at a consistent time of day.
Formula (Mifflin–St Jeor)
Male
BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
Female
BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
Result is shown in kcal/day.
From BMR to your daily calories
BMR is your baseline. To estimate your total daily energy expenditure (TDEE), multiply BMR by an activity factor:
TDEE ≈ BMR × Activity Factor. For weight change, adjust calories relative to TDEE.
Helpful tips
- Use consistent, recent measurements for best accuracy.
- Stick to one unit system (Metric or Imperial) per calculation.
- Re-check entries if your result seems unusually high or low.
Common mistakes
- Mixing cm with pounds, or feet with kilograms.
- Forgetting inches when entering imperial height.
- Entering age in months instead of years.
Frequently asked questions
Why do different calculators give different BMR values?
Different formulas (e.g., Harris–Benedict vs Mifflin–St Jeor) and rounding rules can produce small differences. We use Mifflin–St Jeor.
Is BMR the same as calories burned in a day?
No. BMR is your resting baseline. Your daily burn (TDEE) = BMR × activity factor.
Does muscle mass affect BMR?
Yes. More lean mass generally increases BMR. Two people with the same weight/height can have different BMRs.
Should I change diet based on BMR alone?
Use BMR as a starting point. Consider TDEE, goals, and professional advice before making nutrition changes.
Important note
BMR is an estimate and doesn’t replace medical guidance. Hormones, medications, and health conditions can change energy needs.