Basal Metabolic Rate (BMR) is the amount of energy your body needs to maintain essential life functions — breathing, blood circulation, and regulating body temperature — while completely at rest. It’s essentially the “cost” of simply being alive, without any physical activity, food digestion, or mental exertion factored in.

How the BMR Calculator Works

Our BMR calculator uses the Mifflin-St Jeor equation, widely regarded as the most accurate formula for estimating basal metabolic rate in the general population. Users enter their sex, age, height, and weight, and the calculator determines daily calorie expenditure at rest.

The formula for men is:

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

For women, the calculation is nearly identical, with a small adjustment:

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

The difference between sexes exists because men typically carry more muscle mass, and muscle tissue burns more energy than fat tissue, even at rest.

What the Result Actually Means

The number you get — say, 1,550 calories — represents the minimum energy your body would burn over 24 hours if you stayed in bed all day. It is not a target for how many calories you should eat; rather, it’s a starting point for further calculations.

BMR forms the foundation for calculating Total Daily Energy Expenditure (TDEE), since activity, exercise, and food digestion are added on top of it. This is why BMR is rarely used on its own — it’s most useful when combined with an activity level.

Why This Number Matters

Knowing your basal metabolic rate helps set realistic goals for weight loss, maintenance, or muscle gain. People with a higher BMR (typically those with more muscle mass, taller stature, or younger age) can eat somewhat more without gaining weight, while those with a lower BMR need to plan their food intake more carefully.

It’s worth noting that BMR is an estimate, not a lab-measured value — actual basal metabolism also depends on genetics, hormonal status, and body composition, so real-world values can differ from the calculated figure by a few percent in either direction. CALCULATE HERE