BMR Calculator

Calculate your Basal Metabolic Rate (BMR) to understand how many calories your body burns at rest using the Mifflin-St Jeor equation.

How it works

BMR (Mifflin-St Jeor) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 (men) or − 161 (women). TDEE = BMR × activity factor (1.2 sedentary to 1.9 athlete).

Worked example

A 30-year-old man, 80 kg and 180 cm, has a BMR of about 1,780 calories. Lightly active (×1.375) his TDEE is roughly 2,450 calories per day.

Frequently asked questions

What is the difference between BMR and TDEE?

BMR is what you burn lying still for 24 hours — usually 60–70% of your total. TDEE adds digestion, daily movement and exercise, and is the number to use for diet planning.

Why Mifflin-St Jeor over Harris-Benedict?

Mifflin-St Jeor was validated on modern populations and is typically within 10% of measured values, while the 1919 Harris-Benedict equation overestimates by around 5% for most people.

Does dieting lower BMR?

Yes, modestly. Sustained deficits reduce BMR through lost lean mass and adaptive thermogenesis — usually 5–15%. Resistance training and adequate protein blunt most of that drop.