BMR Calculator
Basal metabolic rate by Mifflin-St Jeor, revised Harris-Benedict and, with a body-fat figure, Katch-McArdle.
At rest
- Harris-Benedict (revised)
- 1,402 kcal
- What your body burns lying still for a day. What you eat to keep your weight is higher: the Calorie Calculator adds your activity.
You
How is this calculated?
Mifflin-St Jeor: 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women)
Harris-Benedict (Roza & Shizgal 1984): 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 mass (kg)Runs in your browser — nothing you enter leaves this device.
A general estimate. BMI and calorie formulas don't account for body composition, pregnancy, or medical conditions. Talk to a doctor before changing diet or exercise.
About this tool
What it does
Your basal metabolic rate (BMR) is the energy your body uses in a day at complete rest: breathing, circulation, keeping warm and repairing tissue. It is most of what you burn, often 60 to 70% for people who are not very active. This calculator gives it by the Mifflin-St Jeor equation, which dietitians’ own review found the most accurate for most adults, alongside the older Harris-Benedict equation and, if you know your body-fat percentage, the Katch-McArdle equation.
How to use it
- Choose your units, then set your sex, age, height and weight.
- If you know your body-fat percentage, switch on the body-fat option and set it.
- Read your BMR by Mifflin-St Jeor, and compare the other equations under it.
- For what to eat in a day, which adds your activity, open the Calorie Calculator.
Limits and your data
- These are equations fitted to groups of people. Individuals vary, typically by up to about 10% either way, and more for very lean, very muscular or very heavy people.
- They are for adults. Children, pregnancy, illness and some medicines change metabolism in ways the equations do not include.
- Katch-McArdle is only as good as the body-fat figure you give it; bathroom scales that estimate body fat can be well off.
- BMR is not what you should eat. Eating only your BMR while active is a large deficit.
- Everything you enter stays in this page. It is not saved, not sent anywhere and not put in the page address: body measurements are personal, so a reload starts from the example values again.
Questions
Which equation should I trust?
Mifflin-St Jeor, for most adults. A review by the Academy of Nutrition and Dietetics found it predicted measured BMR within 10% for more people than the others. Harris-Benedict tends to read slightly higher. If you have an accurate body-fat measurement, Katch-McArdle can be closer, especially for lean, muscular people.
What is the difference between BMR and RMR?
Strictly, BMR is measured after a night’s sleep and a 12-hour fast in a warm, quiet room; resting metabolic rate (RMR) is measured with fewer rules and comes out a little higher. The equations here estimate BMR, and in everyday use the two words mean the same thing.
Why does BMR fall with age?
Mostly because people lose muscle as they age, and muscle uses more energy at rest than fat does. Strength training slows that loss.
Why do men and women get different numbers?
At the same height and weight, men carry more muscle on average. The equations include a different constant for each sex for that reason; it is an average, not a rule for any one person.