BMR Calculator
Your basal metabolic rate (BMR) is the calories your body burns at complete rest.
Example and how to use it
By the Mifflin–St Jeor equation it's 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women — about 1,320 calories a day for a 30-year-old, 165 cm, 60 kg woman. Enter your details to get your BMR (in calories and kJ) and the calories you burn at each activity level; add your body fat % for a Katch–McArdle estimate too.
BMR calculator
| BMR, Mifflin–St Jeor | 1,417 calories/day (5,929 kJ) |
Calories burned per day by activity level
| Sedentary (×1.2) | 1,700 calories |
| Lightly active (×1.375) | 1,950 calories |
| Moderately active (×1.55) | 2,200 calories |
| Very active (×1.725) | 2,440 calories |
| Extra active (×1.9) | 2,690 calories |
BMR by the Mifflin–St Jeor equation. Know your body fat %? Add it to see the Katch–McArdle estimate too. Real needs can be about 10% higher or lower; it's an estimate, not a measurement.
Formula and source: the Mifflin–St Jeor equation
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
US units: 4.536 × weight (lb) + 15.88 × height (in) − 5 × age, then +5 (men) or −161 (women)
The result is in kilocalories per day. The equation comes from Mifflin, St Jeor, Hill, Scott, Daugherty and Koh, “A new predictive equation for resting energy expenditure in healthy individuals”, American Journal of Clinical Nutrition, 1990, 51(2): 241–247. They measured resting energy expenditure by indirect calorimetry in 498 healthy adults aged 19–78 (247 women and 251 men; 264 of normal weight and 234 with obesity) and fitted it to weight, height, age and sex. The US-unit version is the same equation with the conversions built in (1 lb = 0.4536 kg, 1 in = 2.54 cm).
Worked example
A 30-year-old woman, 165 cm, 60 kg: 10 × 60 = 600; 6.25 × 165 = 1,031.25; 5 × 30 = 150. Then 600 + 1,031.25 − 150 − 161 = 1,320.25, so her BMR is about 1,320 calories a day. A man of the same age, height and weight gets +5 instead of −161: 1,486 calories, 166 more.
How accurate it is, and where it stops working
- In a 2005 systematic review for the American Dietetic Association, Mifflin–St Jeor predicted resting metabolic rate within 10% of the measured value in more people — with and without obesity — than Harris–Benedict, Owen or the FAO/WHO/UNU equations. The same review warns that errors for an individual can still be noteworthy.
- It was derived in adults. It isn't meant for children and teenagers, or for pregnancy and breastfeeding.
- Older adults and some ethnic groups were under-represented in the studies behind it, so treat the result with more caution there.
- It works from total weight, not muscle: for very lean, muscular people the lean-mass equation below can fit better. Strictly, the paper measured resting energy expenditure, which runs slightly above true basal rate; calculators use the two terms interchangeably.
- The activity factors further down (1.2–1.9) are conventional multipliers, not part of the 1990 paper. They overlap with, but start lower than, the physical activity levels in the FAO/WHO/UNU report on human energy requirements: 1.40–1.69 for a sedentary or light lifestyle, 1.70–1.99 for an active one and 2.00–2.40 for a vigorous one.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). A new predictive equation for resting energy expenditure in healthy individuals. doi: 10.1093/ajcn/51.2.241.The equation itself, derived from measured resting energy use in 498 healthy adults aged 19–78 (American Journal of Clinical Nutrition, 51(2): 241–247).
- Frankenfield D, Roth-Yousey L, Compher C (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. doi: 10.1016/j.jada.2005.02.005.Systematic review for the American Dietetic Association: Mifflin–St Jeor predicted resting metabolic rate within 10% of measured in more people than any other equation tested.
- Cunningham JJ (1991). Body composition as a determinant of energy expenditure: a synthetic review and a proposed general prediction equation. doi: 10.1093/ajcn/54.6.963.The lean-mass equation, 370 + 21.6 × fat-free mass (kg) — the one calculators call Katch–McArdle.
- FAO / WHO / UNU (2004). Human energy requirements: report of a Joint FAO/WHO/UNU Expert Consultation (Rome, 2001).Physical activity levels (PAL): 1.40–1.69 sedentary or light, 1.70–1.99 active, 2.00–2.40 vigorous (Table 5.3).
Sources last checked on September 30, 2026.
BMR by weight, age and sex
Quick reference by Mifflin–St Jeor for a woman of 5′4″ (163 cm) and a man of 5′9″ (175 cm). Each inch of height adds about 16 calories; each extra decade of age takes away 50.
| Weight | Woman, 30 | Woman, 60 | Man, 30 | Man, 60 |
|---|---|---|---|---|
| 120 lb (54 kg) | 1,249 | 1,099 | 1,495 | 1,345 |
| 140 lb (64 kg) | 1,340 | 1,190 | 1,585 | 1,435 |
| 160 lb (73 kg) | 1,431 | 1,281 | 1,676 | 1,526 |
| 180 lb (82 kg) | 1,521 | 1,371 | 1,767 | 1,617 |
| 200 lb (91 kg) | 1,612 | 1,462 | 1,858 | 1,708 |
| 220 lb (100 kg) | 1,703 | 1,553 | 1,948 | 1,798 |
| 240 lb (109 kg) | 1,794 | 1,644 | 2,039 | 1,889 |
Katch–McArdle: if you know your body fat
Mifflin–St Jeor works from weight, so two people of the same size get the same BMR even if one carries much more muscle. The Katch–McArdle equation uses lean body mass instead: BMR = 370 + 21.6 × lean mass (kg), where lean mass = weight × (1 − body fat %). The equation was proposed by Cunningham in 1991 from a review of studies relating resting energy expenditure to fat-free mass; calculators usually call it Katch–McArdle. It can suit lean, muscular people better — but only if your body fat figure is reliable: a DEXA scan or a careful measurement, not a guess. Enter it in the calculator and you'll see both results side by side; the activity table then uses Katch–McArdle. In energy terms, 1 calorie (kcal) = 4.184 kJ.
From BMR to calories per day
To estimate how many calories you burn in a day (TDEE), multiply BMR by an activity factor:
| Activity level | Factor | Example: BMR 1,320 |
|---|---|---|
| Sedentary — desk job, little or no exercise | ×1.2 | 1,580 calories |
| Lightly active — light exercise or walking 1–3 days a week | ×1.375 | 1,820 calories |
| Moderately active — exercise 3–5 days a week | ×1.55 | 2,050 calories |
| Very active — hard exercise 6–7 days a week | ×1.725 | 2,280 calories |
| Extra active — physical job plus training, or twice-a-day training | ×1.9 | 2,510 calories |
What changes your BMR
More weight and more height mean a higher BMR; each year of age lowers it a little, and at the same size men burn more than women, mostly because of more muscle. Muscle is the part you can change: strength training helps keep BMR from dropping as you age or diet. The formula is an estimate: for most people it lands within about 10% of measured BMR, and for some the error is larger.
To turn BMR into a daily target for weight loss or maintenance, use the maintenance calorie calculator; to split calories into protein, carbs and fat, use the macro calculator.
FAQ
What is BMR?
Basal metabolic rate (BMR) is the number of calories your body burns at complete rest in a day — to keep your heart beating, lungs breathing, brain working and body warm. It's usually the largest part of daily energy use.
What is a normal BMR?
It depends on sex, age, height and weight. By the Mifflin–St Jeor equation, a 30-year-old woman who is 165 cm (5′5″) and 60 kg (132 lb) has a BMR of about 1,320 calories a day; a 30-year-old man who is 180 cm (5′11″) and 80 kg (176 lb), about 1,780.
How do I calculate BMR?
With the Mifflin–St Jeor equation: 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then +5 for men or −161 for women. In pounds and inches: 4.536 × weight (lb) + 15.88 × height (in) − 5 × age, then +5 or −161. Multiply the result by an activity factor from 1.2 to 1.9 to estimate the calories you burn per day.
Where does the Mifflin–St Jeor equation come from?
From a 1990 paper in the American Journal of Clinical Nutrition by Mifflin, St Jeor and colleagues (volume 51, issue 2, pages 241–247), based on resting energy expenditure measured in 498 healthy adults aged 19–78. A 2005 systematic review found it predicted resting metabolic rate within 10% of the measured value in more people than the Harris–Benedict, Owen or FAO/WHO/UNU equations.
What's the difference between BMR and TDEE?
BMR is what you burn at rest. TDEE (total daily energy expenditure) adds everything else — digesting food, daily movement and exercise — and is the number of calories that keeps your weight stable. The calculator shows both.
What is the Katch–McArdle formula?
It estimates BMR from lean body mass: 370 + 21.6 × lean mass in kg, where lean mass is your weight minus your body fat. It doesn't use age or sex, so it only helps if you know your body fat percentage reasonably well. For an 80 kg (176 lb) man with 20% body fat it gives about 1,752 calories, close to the 1,780 from Mifflin–St Jeor.
Should I eat less than my BMR to lose weight?
Generally no. Eating below your BMR for long makes it hard to get enough protein and nutrients and is difficult to sustain. A moderate deficit from your maintenance calories works better; our diary never sets a target below BMR.