BMR Calculator – Basal Metabolic Rate
Calculate how many calories the body burns at rest (BMR) with the Mifflin–St Jeor, Harris–Benedict and Katch–McArdle formulas.
Tip: Don't eat below your BMR for long periods without medical supervision — very strict diets slow metabolism and lose muscle.
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About this digital tool
BMR (Basal Metabolic Rate) is the minimum energy your body uses every day just to maintain vital functions — breathing, blood circulation, temperature and organ work — even if you've stayed in bed all day. It usually makes up 60–70% of the calories you burn in total, so it is the starting point for any nutrition plan.
This calculator uses three well-known formulas: Mifflin–St Jeor (the most reliable for the general population), the revised Harris–Benedict, and Katch–McArdle, which takes lean mass into account when you know your body fat percentage. To find total daily calories, multiply BMR by your activity level or use the TDEE calculator.
How to use
- Choose your gender and enter your age
- Enter your weight (kg) and height (cm)
- Optional: enter your body fat percentage for the Katch–McArdle formula
- Read BMR by each formula and the average
- Multiply it by the activity level or open the TDEE calculator for daily calories
Frequently asked questions
What is BMR and why does it matter?
BMR is the number of calories the body burns at complete rest. It helps you decide how many calories to eat to lose, maintain or gain weight, because every plan starts from this base value.
Which BMR formula is the most accurate?
Mifflin–St Jeor is considered the most accurate for most adults. Katch–McArdle is the best for those who know their body fat percentage, e.g. athletes. Harris–Benedict gives similar results, usually slightly higher.
What is the difference between BMR and TDEE?
BMR is burn at rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by daily activity and exercise — that is, how many calories you actually burn through the whole day.
What changes BMR?
Age (it falls over the years), gender, weight, height and muscle mass. More muscle means a higher BMR, because muscle tissue burns more energy than fat even at rest.
Is the result medically accurate?
No — it is a statistical estimate with a typical error of ±10%. For a personalised nutrition plan, especially with chronic illness or pregnancy, consult a doctor or dietitian.