How to Calculate BMR: Find Your Resting Metabolic Rate Step by Step
By WellnessVigor · Updated October 15, 2026 · 8 min read
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Your basal metabolic rate (BMR) is the number of calories your body burns at complete rest, just to keep you alive: breathing, pumping blood, keeping you warm and repairing cells. It is usually the biggest part of the calories you burn each day.
Knowing your BMR is the first step to working out how much to eat to lose, maintain or gain weight. Here is how to calculate it by hand, with worked examples, and how to use the number.
Quick answer
Use the Mifflin-St Jeor equation. Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. Women: same, but −161 instead of +5. Multiply BMR by your activity factor (1.2–1.9) to get your daily calorie needs. Or use our free {{/bmr-calculator/|BMR Calculator}}.
BMR is measured under strict lab conditions: after a full night’s sleep, fasting, lying still in a warm room. Resting metabolic rate (RMR) is measured under looser conditions and is usually slightly higher, by up to about 10%. In everyday use, the two terms are treated as the same thing, and the formulas below estimate both.
The only way to measure your RMR directly is indirect calorimetry, a test that measures the oxygen you breathe in and carbon dioxide you breathe out. Some clinics and gyms offer it. For most people, a formula is accurate enough.
The best formula: Mifflin-St Jeor
A systematic review comparing BMR equations found the Mifflin-St Jeor equation was the most reliable for most adults, predicting resting metabolic rate within 10% of the measured value more often than the alternatives.
| Metric (kg, cm) | US units (lb, in) | |
|---|---|---|
| Men | 10W + 6.25H − 5A + 5 | 4.536W + 15.88H − 5A + 5 |
| Women | 10W + 6.25H − 5A − 161 | 4.536W + 15.88H − 5A − 161 |
W = weight, H = height, A = age in years.
Worked example 1: a woman
A 35-year-old woman, 165 cm tall, weighing 70 kg:
- 10 × 70 = 700
- 6.25 × 165 = 1,031
- 5 × 35 = 175
- BMR = 700 + 1,031 − 175 − 161 = about 1,395 calories a day
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Worked example 2: a man (US units)
A 40-year-old man, 5 ft 11 in (71 inches), weighing 187 lb:
- 4.536 × 187 = 848
- 15.88 × 71 = 1,127
- 5 × 40 = 200
- BMR = 848 + 1,127 − 200 + 5 = about 1,780 calories a day
Other BMR formulas
- Harris-Benedict (revised 1984): the older classic. Men: 88.36 + 13.40W + 4.80H − 5.68A. Women: 447.59 + 9.25W + 3.10H − 4.33A (kg, cm). It tends to slightly overestimate.
- Katch-McArdle: 370 + 21.6 × lean body mass (kg). Useful if you know your body fat percentage, especially for lean, muscular people.
Our BMR Calculator shows all three side by side.
From BMR to daily calories (TDEE)
BMR is only what you burn at rest. To find your total daily energy expenditure (TDEE), multiply by your activity level:
| Activity | Multiply BMR by |
|---|---|
| Sedentary (desk job, little exercise) | 1.2 |
| Light exercise 1–3 days/week | 1.375 |
| Moderate exercise 3–5 days/week | 1.55 |
| Hard exercise 6–7 days/week | 1.725 |
| Physical job plus training | 1.9 |
The woman above, with a desk job and light exercise, burns about 1,395 × 1.375 = 1,920 calories a day. Eating about 300–500 fewer leads to gradual weight loss. Get your exact numbers with the TDEE Calculator.
What affects your BMR?
- Muscle mass: more muscle means a higher BMR. Strength training helps.
- Body size: bigger bodies burn more.
- Age: BMR falls slowly with age, mostly because of muscle loss.
- Sex: men usually have more muscle and a higher BMR.
- Thyroid hormones, genetics and some medicines.
- Dieting: BMR drops a little as you lose weight. See weight loss plateau.
For ways to raise your daily burn, read how to boost your metabolism when you sit all day.
Tools that help
These are common, inexpensive options that some people find helpful. We have not personally tested these products. Links go to Amazon so you can check current prices and reviews.
BEST FOR TRACKING WEIGHT
Smart scale
Track your weight trend while you test your calorie target. See our smart scale guide.
Pros
- Automatic logging
- Trend charts
Cons
- Body fat is estimated
- App needed
BEST FOR COUNTING CALORIES ACCURATELY
Digital kitchen scale
Weighing food for a few weeks shows you what your calorie target really looks like on a plate.
Pros
- Accurate portions
- Inexpensive
Cons
- Takes a little extra time
- Needs batteries
Keep reading
Frequently asked questions
How do I find my resting metabolic rate?
Use the Mifflin-St Jeor formula or our BMR calculator for a good estimate. For an exact number, ask a clinic about an indirect calorimetry test.
What is a normal BMR?
It depends on your size, age and sex. Many adult women fall roughly between 1,200 and 1,500 calories a day and many adult men between 1,500 and 1,900, but larger or more muscular people can be higher.
Is it OK to eat below my BMR?
For most people, eating below BMR for long periods is not recommended without medical supervision. A modest deficit from your TDEE works better and is easier to keep up.
How accurate are BMR calculators?
For most adults, the Mifflin-St Jeor formula is within about 10% of measured values. Very muscular or very overweight people may see larger differences.
Sources
- Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990.
- Frankenfield D, et al. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr. 1984.
This article is for general information only and is not medical advice. See our Medical Disclaimer.