BMR Calculator

BMR is the number of calories your body burns at complete rest to maintain basic life-sustaining functions — breathing, circulation, cell production, and organ function. It represents the minimum energy your body needs to stay alive if you did absolutely nothing all day. For most people, BMR accounts for 60–75% of total daily calorie burn.

TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor to account for the calories burned through movement and exercise. Eating at your TDEE maintains your current weight. Eating below TDEE creates a calorie deficit for weight loss; eating above TDEE for weight gain. BMR is just the resting component; TDEE is your complete daily energy need.

This calculator uses the Mifflin-St Jeor equation (1990), widely considered the most accurate for most people: Men: (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5. Women: (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161. Research shows it predicts actual measured BMR within 10% for most individuals, outperforming the older Harris-Benedict equation.

To lose weight, eat fewer calories than your TDEE. A deficit of 500 calories/day results in approximately 0.5kg (1 lb) of fat loss per week. A deficit of 1,000 cal/day yields ~1kg/week. Never eat below your BMR for extended periods — it slows metabolism, causes muscle loss, and is nutritionally difficult to sustain. A 20% deficit below TDEE is a safe, sustainable starting point.

TDEE activity multipliers add a significant number of calories on top of BMR. Even "sedentary" includes incidental daily movement. Lightly active (1–3 days/week exercise) gives a multiplier of 1.375× BMR. Moderately active (3–5 days) is 1.55×. Very active (6–7 days) is 1.725×. Many people underestimate their activity level, which is why tracking actual food intake alongside these estimates is valuable.