BMR Calculator

Your basal metabolic rate is the energy your body spends doing nothing. Breathing, pumping blood, keeping cells alive while you lie still. Enter your sex, age, weight and height above and the calculator returns that number in calories per day. It is the single largest slice of what you burn, and every diet decision sits on top of it.

What BMR tells you

BMR is your floor, not your target. A 30-year-old man at 80 kg and 180 cm burns about 1780 calories a day before he so much as stands up. That figure is what keeps the lights on. The food, the walking, the training, the fidgeting all stack on top of it.

This is why two people who eat the same can drift in opposite directions. A bigger body, more muscle, or being younger all push BMR up. Knowing your own number stops you from copying a calorie target that was never built for your frame.

Mifflin-St Jeor or Harris-Benedict

The calculator gives you both. Mifflin-St Jeor is the default because it tracks real measured metabolism more closely for most people and tends to land a touch lower. Harris-Benedict is the older equation and usually reads slightly higher. Pick one and stay with it so you compare like with like over time.

Both are estimates from population averages. Your real BMR can sit a few percent either side depending on body composition, so treat the output as a starting point you refine against the scale, not a fixed truth.

Turning BMR into a daily target

BMR alone is no use for eating. You want TDEE, your total burn including movement and training. Run your number through the TDEE calculator to apply an activity factor, then split that total into food with the macro calculator.

For how to set those macros around adding muscle while holding body fat, read the guide on macros for body recomposition.