BMR Calculator
Estimate Basal Metabolic Rate (kcal/day).
What your BMR actually measures
Basal metabolic rate is the energy your body burns doing nothing at all — keeping your heart beating, your lungs working and your temperature steady while you lie completely still. It is the floor under every calorie target you will ever set, because everything you do during the day is added on top of it. This BMR calculator uses the Mifflin-St Jeor equation, the one most dietitians now prefer.
How to use the BMR Calculator
- Choose your Sex — the equation differs by roughly 166 kcal.
- Enter your Age (years).
- Enter your Weight (kg) and Height (cm).
- Read your BMR in kilocalories per day.
Formula and a worked example
Men: BMR = 10w + 6.25h − 5a + 5
Women: BMR = 10w + 6.25h − 5a − 161
w is weight in kilograms, h height in centimetres and a age in years. To get the calories you actually need in a day, multiply BMR by an activity factor: about 1.2 if sedentary, 1.55 if moderately active, 1.9 if very active.
Worked example
A 30-year-old man, 80 kg and 180 cm: 800 + 1,125 − 150 + 5 = 1,780 kcal at complete rest. Working a desk job (×1.2) he needs about 2,136 kcal a day to hold that weight; training hard (×1.725) closer to 3,070.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is what you burn at rest. TDEE — total daily energy expenditure — is BMR multiplied by an activity factor, and it is the number to use for weight planning.
Why is my BMR falling as I get older?
Muscle mass tends to decline with age and the equation subtracts five calories per year. Resistance training slows both effects.
Can I eat below my BMR to lose weight faster?
It is not advised. Sustained intake below BMR risks muscle loss and nutrient shortfalls. A moderate deficit below TDEE is the safer route.
Which BMR formula is most accurate?
Mifflin-St Jeor, used here, is generally more accurate for modern populations than the older Harris-Benedict equation.
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