Your Basal Metabolic Rate is the energy your body needs to keep you alive at complete rest — breathing, circulation, cell repair. It typically accounts for 60–70% of the calories you burn each day.
How to use the BMR Calculator
- 1 Select your sex and enter your age.
- 2 Enter your weight in kilograms and height in centimetres.
- 3 Compare both equations — Mifflin-St Jeor is generally considered the more accurate today.
Formula
Harris-Benedict (revised 1984) Men: 88.362 + 13.397W + 4.799H − 5.677A Women: 447.593 + 9.247W + 3.098H − 4.330A Mifflin-St Jeor (1990) 10W + 6.25H − 5A + 5 (men) / − 161 (women) W = kg, H = cm, A = years
Worked examples
Input: Male, 30 years, 70 kg, 175 cm
Result: 1,695 kcal/day
Harris-Benedict; Mifflin-St Jeor gives 1,649
Harris-Benedict vs. Mifflin-St Jeor
The Harris-Benedict equation dates from 1919 and was revised in 1984. The Mifflin-St Jeor equation, published in 1990, was found in later reviews to predict resting energy expenditure more accurately for most people, so many dietitians now prefer it. Both are estimates: individual metabolism can differ by 10% or more.
From BMR to daily calories
BMR excludes digestion and activity. To estimate how many calories you actually burn each day, multiply BMR by an activity factor — the TDEE calculator does this for you.
This calculator provides general estimates for healthy adults and is not medical advice. Consult a doctor or registered dietitian before making significant changes to your diet or exercise.
Frequently asked questions
What is the difference between BMR and RMR?
BMR is measured under stricter conditions (fasted, fully at rest). Resting Metabolic Rate is slightly higher, but the terms are often used interchangeably.
Why does BMR decrease with age?
Mostly because lean muscle mass tends to decline with age, and muscle burns more energy than fat.
Should I eat less than my BMR to lose weight?
Generally not. Eating below BMR for long periods can be counter-productive and should only be done under medical supervision.
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