Calories & Nutrition tool
BMR Calculator
Calculate your basal metabolic rate with the Mifflin-St Jeor, Harris-Benedict and Katch-McArdle formulas, in metric or imperial units. Free, nothing stored.
Nothing you enter leaves your device.
Inputs
Results
Enter values to see your results.
Simple steps
How it works
- 01
Enter your sex, age, height and weight.
- 02
Add your body fat percentage if you know it, for the Katch-McArdle formula.
- 03
Select Calculate to compare your BMR from each formula.
Good to know
Frequently asked questions
What is BMR?
Basal metabolic rate is the energy your body uses at complete rest to breathe, keep warm and keep organs working. It is usually 60 to 75% of the calories you burn in a day.
Which formula should I use?
Mifflin-St Jeor is the most accurate for most adults and is shown first. Harris-Benedict is an older, revised formula. Katch-McArdle uses lean body mass, so it suits people who know their body fat percentage, such as athletes.
Why do the formulas give different numbers?
They were built from different groups of people and use different inputs. Differences of 50 to 100 kcal a day are normal.
Is BMR the number of calories I should eat?
No. You burn more than your BMR because you move. Use the Calorie Calculator, which multiplies BMR by your activity level, to find your daily needs.
Where do I get my body fat percentage?
From a body fat scale, a DEXA scan, or an estimate such as our Body Fat Calculator. Leave the field empty to skip Katch-McArdle.
Does it work for children or pregnancy?
No. These formulas are for adults who are not pregnant.
Is anything I enter stored or sent?
No. The calculation runs in your browser. Nothing you type is saved or sent to a server.
How it is calculated
Mifflin-St Jeor: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, + 5 for men or − 161 for women. Harris-Benedict (revised by Roza and Shizgal): men 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age; women 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age. Katch-McArdle: 370 + 21.6 × lean body mass (kg).
Sources
- Mifflin MD et al. Am J Clin Nutr 1990;51:241–7
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr 1984;40:168–82
- McArdle WD, Katch FI, Katch VL. Exercise Physiology (Katch-McArdle equation)
Last reviewed: October 14, 2026