BMR Calculator

What Is a BMR Calculator?

A Basal Metabolic Rate (BMR) calculator estimates the number of calories your body needs to maintain basic physiological functions at rest, such as breathing, circulation, and cell production. BMR represents the minimum energy your body requires just to stay alive without any physical activity.

How to Use This BMR Calculator

1. Enter your weight in kilograms and height in centimeters.
2. Enter your age and select your gender.
3. Click Calculate to see your BMR from two well-known formulas, plus estimated daily calorie needs at different activity levels.

BMR Formulas Explained

This tool uses two widely recognized equations to estimate BMR. The Mifflin-St Jeor equation, developed in 1990, is considered the most accurate for the general population. The revised Harris-Benedict equation, originally from 1919 and updated in 1984, remains a popular alternative.

Mifflin-St Jeor:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Harris-Benedict (revised):
Men: BMR = 13.397 × weight(kg) + 4.799 × height(cm) − 5.677 × age + 88.362
Women: BMR = 9.247 × weight(kg) + 3.098 × height(cm) − 4.330 × age + 447.593

BMR vs. TDEE

BMR measures only resting energy expenditure, while Total Daily Energy Expenditure (TDEE) adds calories burned through physical activity and digestion. Your TDEE is always higher than your BMR. To estimate TDEE, multiply your BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active). The activity level table below shows these estimates using your Mifflin-St Jeor BMR.

Frequently Asked Questions

Which BMR formula is more accurate?

The Mifflin-St Jeor equation is generally considered more accurate for modern populations. A 2005 study by the American Dietetic Association found it predicted resting metabolic rate within 10% for most healthy adults, outperforming the Harris-Benedict equation.

Why does my BMR decrease with age?

As you age, muscle mass naturally declines and is replaced by fat tissue. Since muscle burns more calories at rest than fat, losing muscle mass lowers your BMR. Regular strength training can help slow this decline.

Can I increase my BMR?

Yes. Building lean muscle through resistance training is the most effective way to raise your BMR. Staying well-hydrated and getting adequate sleep also support a healthy metabolic rate.