BMR Calculator

What is BMR?

Basal Metabolic Rate is the energy your body uses at complete rest to keep your heart beating, your lungs working and your organs running. For most people it makes up 60–70% of the calories they burn in a day, which is why it is the starting point for every nutrition plan.

Three formulas, side by side

• Mifflin-St Jeor: the most accurate for most adults and the one most dietitians use today.
• Harris-Benedict: the classic formula (revised in 1984). It usually comes out slightly higher.
• Katch-McArdle: uses your lean body mass instead of total weight. Enter your body fat percentage to unlock it; it is the best choice for lean, muscular people.

Small differences between the formulas are normal. Each one was built from a different group of people.

What to do with your BMR

Don't eat at your BMR. It doesn't include any movement, so eating that little for long periods slows you down and makes it hard to keep muscle. Use it to work out your daily needs instead: the activity table shows your BMR multiplied by your activity level, or you can go straight to the TDEE Calculator.

Your BMR drops a little as you lose weight and rises as you build muscle, so recalculate every 4–6 kg of change.