BMR Calculator
Estimate your basal metabolic rate: the energy your body burns at complete rest, just to keep you alive and warm.
How your BMR is worked out
Your size, age and sex go into a formula that estimates the energy you burn lying still all day.
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Your details
65 kg · 165 cm
30 years · woman - 2
Mifflin–St Jeor
10×65 + 6.25×165
− 5×30 − 161 - 3
Your BMR
= 1,370 kcal a day
≈ 57 kcal an hour - 4
Times activity
1,370 × 1.375
≈ 1,884 kcal a day
Read more: the formulas, a worked example and BMR vs TDEE
Your basal metabolic rate (BMR) is the energy your body uses lying completely still for a whole day: breathing, pumping blood, keeping warm, and running your brain, liver and kidneys. Scientists measure it with a mask that tracks the oxygen you breathe in; the formulas below are fitted to thousands of those measurements, so they give a good estimate from your size, age and sex. In Advanced you can switch formula, add your body fat for the lean-mass formulas and see every result side by side.
The formula
BMR (Mifflin–St Jeor) = 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then + 5 for men or − 161 for women
Daily burn (TDEE) = BMR × activity factor
| Formula | BMR in kcal a day |
|---|---|
| Mifflin–St Jeor (1990) | 10W + 6.25H − 5A + 5 (men) or − 161 (women) |
| Harris–Benedict, revised (Roza and Shizgal, 1984) | Men: 88.362 + 13.397W + 4.799H − 5.677A Women: 447.593 + 9.247W + 3.098H − 4.330A |
| Harris–Benedict, original (1919) | Men: 66.473 + 13.7516W + 5.0033H − 6.755A Women: 655.0955 + 9.5634W + 1.8496H − 4.6756A |
| Katch–McArdle | 370 + 21.6 × lean mass |
| Cunningham (1980) | 500 + 22 × lean mass |
W is weight in kg, H is height in cm, A is age in years. Lean mass is your weight × (1 − body fat %), in kg.
| WHO/FAO/UNU (1985), by age | Men | Women |
|---|---|---|
| 18 to 29 | 15.3W + 679 | 14.7W + 496 |
| 30 to 59 | 11.6W + 879 | 8.7W + 829 |
| 60 and over | 13.5W + 487 | 10.5W + 596 |
The WHO equations use only weight, age band and sex. They come from Schofield's large collection of measurements and are often used in public health and nutrition planning.
Worked example
A 30-year-old woman who is 165 cm tall and weighs 65 kg: Mifflin–St Jeor gives 10 × 65 + 6.25 × 165 − 5 × 30 − 161 = 650 + 1,031.25 − 150 − 161 = 1,370.25 kcal a day, about 1,370 kcal. That's 1,370.25 ÷ 24 = about 57 kcal an hour, or 1,370.25 × 4.184 = about 5,733 kJ a day.
The other formulas: revised Harris–Benedict 447.593 + 9.247 × 65 + 3.098 × 165 − 4.330 × 30 = 447.593 + 601.055 + 511.17 − 129.9 = 1,429.9 kcal; original Harris–Benedict 655.0955 + 621.621 + 305.184 − 140.268 = 1,441.6 kcal; WHO (age 30 to 59) 8.7 × 65 + 829 = 565.5 + 829 = 1,394.5 kcal. So the spread is 1,441.6 − 1,370.25 = about 71 kcal. If she knew her body fat was 28%, her lean mass would be 65 × 0.72 = 46.8 kg, giving Katch–McArdle 370 + 21.6 × 46.8 = 1,380.9 kcal and Cunningham 500 + 22 × 46.8 = 1,529.6 kcal.
With light exercise 1 to 3 days a week, her daily burn is about 1,370.25 × 1.375 = 1,884 kcal.
Activity factors
| Activity level | Factor |
|---|---|
| Little or no exercise | × 1.2 |
| Light exercise 1–3 days a week | × 1.375 |
| Moderate exercise 3–5 days a week | × 1.55 |
| Hard exercise 6–7 days a week | × 1.725 |
| Very hard exercise or a physical job | × 1.9 |
These are the same factors the calorie calculator uses. To see how much to eat to keep, lose or gain weight, with a goal-weight plan, use that calculator; this page stays with BMR itself.
BMR, RMR and TDEE
BMR is measured in strict lab conditions: after a night's sleep, 12 hours without food, lying still in a warm room. RMR (resting metabolic rate) is measured more loosely and usually comes out a little higher. TDEE (total daily energy expenditure) is everything you burn in a day: BMR plus movement, exercise and digesting food.
Which formula to pick
- Mifflin–St Jeor is one of the most accurate for most adults today, and the usual default.
- Harris–Benedict is the classic formula from 1919, revised in 1984. It tends to read a little higher.
- Katch–McArdle and Cunningham use lean mass, so they suit lean, muscular people who know their body fat from a reliable test. Cunningham reads higher and is popular with athletes.
- WHO uses only weight, sex and age band, so it's handy when height isn't known.
These are estimates for healthy adults. Individual BMR can differ by 10% or more because of muscle mass, genetics, hormones, illness and medicines. They're not suitable for pregnancy, breastfeeding, under-18s or for medical decisions. Talk to a doctor or registered dietitian before making big changes to how you eat.
Common questions
What is BMR?
Basal metabolic rate (BMR) is the energy your body uses in a day lying completely still: breathing, pumping blood, keeping warm and running your organs. It's usually the biggest part of the calories you burn. For a 30-year-old woman who is 165 cm tall and weighs 65 kg, Mifflin–St Jeor gives about 1,370 kcal a day.
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest. TDEE (total daily energy expenditure) adds everything else you do: walking, work, exercise and digesting food. You get an estimate of TDEE by multiplying BMR by an activity factor, from 1.2 for little or no exercise up to 1.9 for very hard exercise or a physical job.
Is BMR the same as RMR?
Nearly. BMR is measured under strict lab conditions: after a night's sleep, fasting and lying still. Resting metabolic rate (RMR) is measured more loosely, so it usually comes out a little higher. The formulas on this page estimate BMR, and in everyday use the two words are often treated as the same thing.
Which BMR formula is the most accurate?
For most adults, Mifflin–St Jeor is one of the most accurate and is the usual default. Harris–Benedict is older and tends to give slightly higher figures. Katch–McArdle and Cunningham work from lean mass, so they suit people who know their body fat well, such as from a DEXA scan. Formulas often differ by 50 to 150 kcal a day.
Why does my BMR go down with age?
Most formulas take a little off for each year of age; Mifflin–St Jeor removes 5 kcal a day per year. That reflects the loss of muscle and small changes in organ size that tend to come with age. Keeping active and strong helps hold on to lean mass, which is what burns most of the energy.
Should I eat my BMR in calories?
Your BMR is not a diet target. It's only what you'd burn lying still all day, so most people need noticeably more. Use the calorie calculator to see daily needs for your activity level and gentle targets to lose or gain weight, and speak to a doctor or dietitian before making big changes.
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