What is basal metabolic rate?
Basal metabolism powers functions such as breathing, circulation, and cell maintenance. Strict BMR measurement requires controlled conditions; Mifflin–St Jeor predicts resting energy expenditure, which is closely related but not identical.
The Mifflin–St Jeor equation
The equation uses kilograms, centimetres, and age in years. Its original male coefficient is +5 and female coefficient is −161. Imperial entries are converted before calculation. No activity multiplier is applied to the BMR result.
How to use this calculator
- 1Select your preferred measurement units.
- 2Enter your adult age, height, weight, and equation coefficient.
- 3Calculate, then use TDEE if you need an estimate that includes daily activity.
Understanding your result
This result estimates resting energy use only. It is not your total daily expenditure or an automatically appropriate food intake. A laboratory measurement may be useful when clinical decisions require a more individualized assessment.
Assumptions & limitations
- Muscle mass, medications, illness, and hormonal differences are not directly included.
- BMR is not a universal safe minimum calorie intake; nutrition needs require broader context.
Frequently asked questions
Is BMR the same as resting metabolic rate?+
They are related, but measured BMR uses stricter test conditions. Mifflin–St Jeor predicts resting energy expenditure even though online tools commonly call the result BMR.
Why does the formula ask for age?+
Age is a predictor in the original equation. At the same height and weight, the equation subtracts five kcal per year; that is a statistical relationship, not a personal measurement.
Does the BMR calculation include a workout?+
No. Use an activity-adjusted TDEE estimate for daily energy needs that include your usual movement and training.
Can I raise BMR by gaining muscle?+
Body composition influences resting energy use, but the change varies. This equation does not directly measure muscle and cannot predict the effect of a particular training plan.
