BMR Calculator

Your Basal Metabolic Rate (BMR) is the energy your body would use if you did nothing but rest all day — the calories that keep your heart beating, your lungs working, and your cells repairing. For most people it's the biggest single chunk of daily calorie use, before any movement is added.

BMR is a useful starting point for managing weight, but it isn't your daily calorie need on its own. To get that, you multiply BMR by an activity factor — which is exactly what the TDEE calculator does. Think of BMR as the floor and TDEE as the whole room.

As with any equation, it's a well-informed estimate. Real resting metabolism varies from person to person by roughly ±10–15% for reasons the formula can't see, such as body composition, genetics, and hormones.

Formula. We use the Mifflin-St Jeor equation: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women, the same with − 161 instead of + 5. Imperial input is converted first, and the result is rounded to a whole calorie.

Why this formula. Mifflin-St Jeor is the general-population resting-energy equation recommended by the Academy of Nutrition and Dietetics, validated against measured resting energy expenditure across a wide range of body sizes.

Confidence. We label BMR moderate confidence: the equation is well validated, but individual metabolism varies, so treat the number as a reliable estimate to plan around rather than an exact measurement.