How to use
- Choose your sex and enter age, height (cm) and weight (kg).
- If you know your body fat percentage, add it to also get the Katch-McArdle result.
- Read your BMR, then find the row in the table that matches how active you are — that is roughly how much you burn per day.
Options explained
- Mifflin-St Jeor
- Published in 1990 and rated the most accurate for most people by the Academy of Nutrition and Dietetics, so it is the main result. Men = 10 × weight + 6.25 × height − 5 × age + 5; for women the last term is −161.
- Harris-Benedict (revised)
- The classic 1919 formula with the 1984 coefficients by Roza and Shizgal. It usually comes out a few dozen kcal higher than Mifflin-St Jeor.
- Katch-McArdle
- 370 + 21.6 × lean body mass (kg), the same for men and women. Better for people with very high or low body fat or a lot of muscle, but it needs a reasonably accurate body fat figure.
- Activity factor
- TDEE = BMR × activity factor, from 1.2 for sedentary to 1.9 for a physical job.
Worked example
A 30-year-old man, 175 cm and 70 kg:
- Mifflin-St Jeor: 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = 1,649 kcal/day
- Harris-Benedict: about 1,696 kcal/day
- Katch-McArdle at 15% body fat: 370 + 21.6 × 59.5 = 1,655 kcal/day
- Moderate exercise 3–5 days a week (× 1.55): TDEE about 2,556 kcal/day
Frequently asked questions
Is BMR the same as the calories I burn in a day?
No. BMR is only what you burn at rest. Total daily energy expenditure (TDEE) adds daily activity, exercise and digesting food, and is typically 1.2 to 1.9 times BMR.
Can I eat less than my BMR to lose weight?
Staying below BMR for long is generally not advised. A common approach is to eat 300–500 kcal a day below TDEE. Very low intake over time can cost muscle and nutrients and should be supervised by a doctor or dietitian.
How accurate is it?
The formulas give the average for people like you; an individual can differ by 10% or more. Eat to the estimate for two or three weeks, then adjust by how your weight actually changes.
Does BMR fall with age?
Yes. In Mifflin-St Jeor each extra year lowers the result by 5 kcal, largely because of lost muscle. Strength training helps keep muscle.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.