BMR Calculator
Calories your body burns at rest, from your weight in lb or kg. Mifflin-St Jeor, compared with the revised Harris-Benedict equation and, if you know your body fat, Katch-McArdle.
Your BMR
1,783 kcal/day
Mifflin-St Jeor equation, at complete rest- Harris-Benedict (revised) 1,865 kcal
- Katch-McArdle add body fat %
- Cunningham add body fat %
- Lean body mass add body fat %
What your BMR means
Your BMR is the energy your body uses at complete rest over 24 hours. It is not how much to eat: it leaves out everything you do while awake. Multiply it by an activity factor to get your daily calories, which is what our TDEE calculator does.
The three equations rarely agree to the calorie. For the default profile, Mifflin-St Jeor gives 1,783 kcal and revised Harris-Benedict gives 1,865 kcal, a gap of 82 kcal. Mifflin-St Jeor is the main number because a 2005 systematic review found it the most often within 10% of measured resting energy. The revisers of Harris-Benedict reported a precision of about ±14%.
- Mifflin-St Jeor: the default for most adults.
- Harris-Benedict (revised 1984): the older standard, shown for comparison.
- Katch-McArdle and Cunningham: use lean body mass, so they fit very muscular people better, if your body fat number is measured, not guessed.
The formulas
Mifflin-St Jeor (1990)
Men: 10W + 6.25H − 5A + 5
Women: 10W + 6.25H − 5A − 161
Harris-Benedict, revised (1984)
Men: 88.362 + 13.397W
+ 4.799H − 5.677A
Women: 447.593 + 9.247W
+ 3.098H − 4.330A
Katch-McArdle: 370 + 21.6 × LBM
Cunningham: 500 + 22 × LBM
LBM = W × (1 − body fat % / 100)
W = weight (kg), H = height (cm),
A = age (years), LBM in kgThe revised Harris-Benedict coefficients are those published by Roza and Shizgal in 1984, as reproduced in secondary sources; we did not have access to the full paper, so treat the last decimal as approximate. Katch-McArdle is a textbook equation (McArdle, Katch and Katch, Exercise Physiology); the source linked below reproduces it. Cunningham's 1980 reanalysis is the peer-reviewed paper behind the lean-mass approach.
Worked example in pounds
A 30-year-old man, 180 lb (81.6 kg), 5 ft 10 in (177.8 cm), 20% body fat:
- Mifflin-St Jeor = 10 × 81.6 + 6.25 × 177.8 − 5 × 30 + 5 = 1,783 kcal
- Harris-Benedict = 1,865 kcal
- LBM = 81.6 × 0.80 = 65.3 kg; Katch-McArdle = 370 + 21.6 × 65.3 = 1,781 kcal
Worked example in kilograms
A 45-year-old woman, 70 kg, 163 cm, body fat unknown:
- Mifflin-St Jeor = 10 × 70 + 6.25 × 163 − 5 × 45 − 161 = 1,333 kcal
- Harris-Benedict = 1,405 kcal
- Katch-McArdle and Cunningham: not computed without a body fat percentage.
BMR by age
Same sex, weight and height as the calculator above, at each age. BMR falls by 5 kcal a day per year of age in Mifflin-St Jeor.
| Age | Mifflin-St Jeor | Harris-Benedict |
|---|---|---|
| 20 | 1,833 | 1,922 |
| 30 | 1,783 | 1,865 |
| 40 | 1,733 | 1,808 |
| 50 | 1,683 | 1,752 |
| 60 | 1,633 | 1,695 |
| 70 | 1,583 | 1,638 |
The Mifflin-St Jeor sample was aged 19 to 78; the calculator accepts 18 to 80.
Frequently asked questions
What is BMR?
BMR stands for basal metabolic rate: the calories your body would burn in a day lying completely at rest, just to keep breathing, circulating blood and holding body temperature. For most people it is the largest part of daily energy use. The equations on this page predict it from weight, height, age and sex, or from lean body mass.
Which BMR formula is the most accurate?
In a 2005 systematic review of healthy adults, the Mifflin-St Jeor equation predicted resting energy within 10% of the measured value for more people than the other common equations, including Harris-Benedict. That is why it is the main number here. Katch-McArdle and Cunningham use lean body mass, so they are only as good as your body fat measurement.
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest; TDEE adds everything you do in a day, so it is always higher. TDEE is BMR times an activity factor from 1.2 to 1.9. For the default profile on this page, BMR is 1,783 kcal and TDEE at a moderate activity level is 2,763 kcal.
How do I calculate lean body mass?
Lean body mass is your weight minus your fat mass: weight × (1 − body fat % / 100). At 80 kg and 20% body fat, that is 80 × 0.8 = 64 kg. Enter a body fat percentage in the calculator and it shows your lean mass along with the Katch-McArdle and Cunningham estimates. Your body fat has to come from a measurement such as a DEXA scan, calipers or a bioimpedance scale; this page does not estimate it.
Should I eat my BMR to lose weight?
Your BMR is not a target. It only covers what you burn at rest, so eating at your BMR already means a deficit for anyone who moves during the day. To set a weight-loss target, start from your TDEE instead; our calorie deficit calculator does that and keeps a minimum intake. Talk to your doctor or a registered dietitian before eating far below your TDEE.
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Medical disclaimer
This calculator gives an estimate, not medical advice. Equations predict the average of a group; your own needs can sit 10% or more above or below. It is built for healthy adults. If you are pregnant or breastfeeding, under 18, living with a medical condition such as diabetes, kidney disease or an eating disorder, or taking medication that affects appetite or weight, ask your doctor or a registered dietitian before acting on these numbers.
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. DOI: 10.1093/ajcn/51.2.241
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775-789. DOI: 10.1016/j.jada.2005.02.005
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168-182. DOI: 10.1093/ajcn/40.1.168
- Physiology Labs at Home (Irvine Valley College, LibreTexts), 4.2: Calculating RMR based off of lean body mass. Reproduces the Katch-McArdle equation BMR = 370 + 21.6 x LBM (kg) from McArdle, Katch and Katch, Exercise Physiology.
- Cunningham JJ. A reanalysis of the factors influencing basal metabolic rate in normal adults. Am J Clin Nutr. 1980;33(11):2372-2374. DOI: 10.1093/ajcn/33.11.2372