BMR Calculator
Estimate your basal metabolic rate with three standard formulas.
What is BMR?
Basal metabolic rate (BMR) is the energy your body uses at complete rest to keep you alive: breathing, circulation and cell repair. It is usually the largest part of the calories you burn in a day. To estimate the calories you burn including activity, use the calorie calculator.
The formulas
- Mifflin-St Jeor: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then +5 for men or −161 for women.
- Revised Harris-Benedict: men 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age. Women 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age.
- Katch-McArdle: 370 + 21.6 × lean body mass (kg), where lean mass = weight × (1 − body fat %). It needs a body fat estimate.
Worked example
A 35-year-old who is 170 cm tall and weighs 70 kg:
- Man: Mifflin-St Jeor 1,593 kcal a day, Revised Harris-Benedict 1,643. With 20% body fat, Katch-McArdle gives 1,580.
- Woman: Mifflin-St Jeor 1,427 kcal a day and Revised Harris-Benedict 1,470.
Frequently asked questions
Which BMR formula is the most accurate?
Mifflin-St Jeor is widely used for healthy adults. Katch-McArdle can be better for very lean or muscular people if your body fat estimate is good. All formulas are estimates.
Is BMR the same as the calories I should eat?
No. BMR is only what you burn at rest. Your daily needs also include movement and exercise, and what is right for you depends on your health and goals.
Why does my BMR change over time?
It changes with weight, muscle mass and age. Larger bodies and more muscle use more energy at rest.
Who should not rely on this calculator?
It is designed for healthy adults aged 18 and over. For pregnancy, medical conditions or advice about weight, talk to a doctor or registered dietitian.
This calculator is for general information only and is not medical or nutrition advice.