About the BMR Calculator
Your Basal Metabolic Rate is the energy your body burns just staying alive. This calculator computes it with the Mifflin-St Jeor equation and shows your total daily burn at all five activity levels.
Your age, weight and height are used in the browser and immediately discarded. Nothing is sent to a server or attached to any profile.
Results are estimates for general information only and are not medical advice. Talk to a healthcare professional before making significant changes to your diet or exercise.
How to use it
- Enter your age, sex, height and weight.
- Choose your activity level.
- Read your BMR and your estimated daily requirement (TDEE).
BMR versus TDEE
BMR is what your body burns at complete rest — breathing, circulation, temperature, brain function. It is typically 60–70% of total daily energy use.
TDEE is BMR multiplied by an activity factor, from about 1.2 for sedentary to 1.9 for very heavy training. TDEE is the number relevant to eating; BMR is the floor beneath it.
The calculation uses the Mifflin-St Jeor equation, which is generally accepted as the most accurate of the common formulas for the general population.
A worked example
Male, 32, 78 kg, 175 cm:
(10 × 78) + (6.25 × 175) − (5 × 32) + 5 = 1,719 kcal BMR.
Moderately active (×1.55) → 2,664 kcal TDEE.
Female, 29, 64 kg, 165 cm:
(10 × 64) + (6.25 × 165) − (5 × 29) − 161 = 1,365 kcal BMR.
Lightly active (×1.375) → 1,877 kcal TDEE.
Common mistakes
- Overstating activity level, which is the single biggest source of error. Most desk workers who exercise three times a week are 'lightly active', not 'very active'.
- Eating at BMR rather than TDEE, which produces a far steeper deficit than intended.
- Recalculating too rarely — BMR falls as weight falls, so the target moves as you progress.
Questions people ask
Which formula is most accurate?
Mifflin-St Jeor is generally preferred over the older Harris-Benedict equation for the general population. Neither accounts for body composition, so both are estimates.
Why is the male figure higher at the same weight?
On average men carry more lean mass, which is metabolically more active. The equation reflects that with a constant of +5 for men and −161 for women.
Should I eat below my BMR to lose weight faster?
Sustained intake below BMR is generally discouraged and can be unsafe. Any substantial deficit is worth discussing with a clinician or dietitian.