BMR Calculator

What is BMR?

Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic life functions — breathing, circulation, cell production, and temperature regulation. BMR accounts for 60-75% of your total daily energy expenditure, making it the largest component of your metabolism.

The Mifflin-St Jeor Equation

Developed in 1990, the Mifflin-St Jeor equation is considered the most accurate BMR formula for modern populations. It was validated against indirect calorimetry in a study of nearly 500 individuals. For men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161.

Factors That Affect BMR

Age: BMR decreases about 1-2% per decade after age 20. Muscle mass: More muscle = higher BMR because muscle burns more calories than fat at rest. Gender: Men typically have higher BMR due to greater muscle mass. Genetics: Some people naturally have faster or slower metabolisms. Climate: Living in cold environments can increase BMR.

How to Use Your BMR

Your BMR tells you the minimum calories your body needs. Eating below your BMR for extended periods can slow your metabolism and cause muscle loss. Use BMR as the foundation for calculating your TDEE (Total Daily Energy Expenditure) by multiplying by your activity factor.

BMR Calculator for Weight Loss

To lose weight sustainably, aim for a daily calorie intake between your BMR and TDEE — never below BMR. Eating below your BMR triggers metabolic adaptation where your body conserves energy, making weight loss harder. A safe deficit is 300-500 calories below TDEE. For example, if your TDEE is 2200 and BMR is 1600, aim for 1700-1900 calories per day.

How to Increase Your BMR Naturally

Build muscle mass through resistance training — each kilogram of muscle burns about 13 calories per day at rest. Eat enough protein (1.6-2.2g/kg). Stay hydrated — even mild dehydration can slow metabolism. Get adequate sleep — sleep deprivation lowers BMR by disrupting hormones. Avoid severe calorie restriction which can permanently lower BMR.

BMR Differences Between Men and Women

Men typically have 10-15% higher BMR than women of the same weight and age, primarily due to greater muscle mass and lower body fat percentage. Hormonal differences also play a role — testosterone promotes muscle growth, while estrogen favors fat storage. After menopause, women's BMR decreases as estrogen levels drop.