BMR Calculator

Estimate the calories your body uses at rest, compared across the main equations.

Sex

Age

Height

Weight

Body fat % (optional)

Adds Katch-McArdle, which works from lean mass.

Energy unit

Choose a sex, then enter your age, height and weight to see the result.

Add your activity in the Calorie Calculator for the calories you burn in a day.

Estimates the calories your body uses at rest in a day, your basal metabolic rate (BMR), from your sex, age, height and weight. It gives Mifflin-St Jeor as the main figure and sets the other main equations beside it, each with the people it was fitted on, so you see how far they agree. With a body fat percentage it adds Katch-McArdle, which works from lean mass. Every calculation runs in your browser.

Understanding the result

BMR is the energy for breathing, circulation and the other work of a body at rest, before any movement or digestion, and the larger part of what most people burn in a day. The range across the equations is the lowest and highest of the equations shown; a measured BMR can sit outside it. To turn BMR into the calories you burn in a day, multiply it by your activity, as the Calorie Calculator does.

How it works

Mifflin-St Jeor is used with the coefficients printed in the 1990 paper, 9.99, 6.25 and 4.92; the 10, 6.25 and 5 seen on most sites round them, and differ by a few kcal. Harris-Benedict is Roza and Shizgal's 1984 refit. Schofield's equations, which the FAO/WHO/UNU 2004 report uses, and Henry's Oxford equations both use weight alone, in the age bands 18–30, 30–60, 60 and over; the tables print 30 and 60 in two bands each, and here each age starts the band it opens. Henry's data leave out the Italian subjects in Schofield's and add many people from the tropics. Katch-McArdle takes lean mass, your weight less its fat.

Strictly, Mifflin-St Jeor predicts resting energy expenditure, or resting metabolic rate (RMR), measured at rest under less strict conditions than a basal measurement; calculators, this one included, treat the two as one. Results are shown to the nearest 10 kcal, and kJ are kcal × 4.184.

Mifflin-St Jeor: 9.99 × kg + 6.25 × cm − 4.92 × age + 5 (men) or − 161 (women)

Harris-Benedict (revised): men 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age; women 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age

Schofield, men: 15.057 × kg + 692.2 (18–30), 11.472 × kg + 873.1 (30–60), 11.711 × kg + 587.7 (60 and over)

Schofield, women: 14.818 × kg + 486.6 (18–30), 8.126 × kg + 845.6 (30–60), 9.082 × kg + 658.5 (60 and over)

Henry, men: 16 × kg + 545 (18–30), 14.2 × kg + 593 (30–60), 13.5 × kg + 514 (60 and over)

Henry, women: 13.1 × kg + 558 (18–30), 9.74 × kg + 694 (30–60), 10.1 × kg + 569 (60 and over)

Katch-McArdle: 370 + 21.6 × lean mass in kg

Examples

A woman of 35, 165 cm and 64 kg

Mifflin-St Jeor gives 1,340 kcal, and the equations span 1,320–1,400 kcal.

A man of 30, 180 cm and 85 kg, with 18% body fat

Mifflin-St Jeor gives 1,830 kcal and Katch-McArdle 1,880 kcal; across all the equations, 1,800–1,920 kcal.

BMR by weight

Mifflin-St Jeor BMR at age 35 for a woman of 163 cm and a man of 177 cm, in kcal a day

Weight	Woman, 163 cm	Man, 177 cm
50 kg	1,190 kcal	1,440 kcal
60 kg	1,280 kcal	1,540 kcal
70 kg	1,380 kcal	1,640 kcal
80 kg	1,480 kcal	1,740 kcal
90 kg	1,580 kcal	1,840 kcal
100 kg	1,680 kcal	1,940 kcal
110 kg	1,780 kcal	2,040 kcal

Rules and sources

Mifflin-St Jeor (1990) was fitted on 498 healthy adults aged 19 to 78: 264 of normal weight and 234 with obesity; below 19 or above 78 the calculator says so beside the result. Harris-Benedict is Roza and Shizgal's 1984 refit of the original data. Schofield's equations are from the FAO/WHO/UNU 2004 report, Table 5.2, Henry's from Table 12 of his 2005 paper, and Katch-McArdle is in the form Cunningham (1991) gives. The equations are for adults; the calculator gives no result under 18.

Sources

Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals (Am J Clin Nutr 1990;51:241–247) — American Journal of Clinical Nutrition
Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass (Am J Clin Nutr 1984;40:168–182) — American Journal of Clinical Nutrition
Human energy requirements: report of a joint FAO/WHO/UNU expert consultation (2004), chapters 5–7 — FAO
Henry CJK. Basal metabolic rate studies in humans: measurement and development of new equations (Public Health Nutr 2005;8(7A):1133–1152), Tables 12 and 17 — Public Health Nutrition
Cunningham JJ. Body composition as a determinant of energy expenditure: a synthetic review and a proposed general prediction equation (Am J Clin Nutr 1991;54:963–969) — American Journal of Clinical Nutrition
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;105:775–789) — Journal of the American Dietetic Association

Reviewed 20 October 2026

Frequently asked questions

A 2005 systematic review by Frankenfield and colleagues found Mifflin-St Jeor the most reliable of the common equations for healthy adults, both with and without obesity, which is why it is the main figure here. Any equation can be well off for one person; Katch-McArdle helps when you are leaner or more muscular than average and know your body fat.

No. BMR is the energy at rest; a day adds movement, exercise and digestion. FAO/WHO/UNU's lifestyles put a day at 1.40 to 2.40 times BMR. That total is your TDEE, which the Calorie Calculator works out from BMR and your activity.