BMR Calculator
Calculate your basal metabolic rate using the Mifflin-St Jeor equation.
Your BMR
What does this mean?
Your Basal Metabolic Rate (BMR) is the number of calories your body burns while at rest. This accounts for basic bodily functions like breathing and circulation. It does NOT include calories burned from daily movement or exercise.
About this tool
The BMR calculator uses the Mifflin-St Jeor equation to estimate your basal metabolic rate, which is the energy your body burns at complete rest. Enter your sex, age, height, and weight, and it returns calories per day. It is the foundation for any cutting or bulking calorie target.
How to use it
- 1 Enter your sex, age, height, and weight.
- 2 Select your preferred unit system if needed.
- 3 Read your estimated BMR in calories per day.
- 4 Use this as the base for TDEE or a cutting/bulking target.
Frequently asked questions
What is the Mifflin-St Jeor equation?
It is the most widely used BMR equation, published in 1990 and validated against indirect calorimetry. It estimates resting energy expenditure from sex, age, height, and weight, and is more accurate than the older Harris-Benedict formula.
How accurate is a BMR estimate?
The Mifflin-St Jeor equation is accurate within about 10% for most people. Muscle mass, thyroid function, and genetics cause real variation, so treat the number as a starting point and adjust based on real-world results.
Educational use only — not medical advice. Results are estimates based on published formulas and models.