BMR Calculator
BMR from Mifflin-St Jeor or the revised Harris-Benedict equation: enter sex, age, weight and height for calories at rest and at five activity levels. How it works
Use the BMR Calculator
About the BMR Calculator
BMR by the Mifflin-St Jeor equation is 10 × weight in kg + 6.25 × height in cm − 5 × age, plus 5 for men or minus 161 for women. A 25-year-old man who weighs 70 kg and is 170 cm tall burns an estimated 1643 kcal a day at rest, and a woman with the same numbers 1477. The calculator then multiplies BMR by an activity factor from 1.2 to 1.9 to estimate daily calories. Its Formula switch also offers Harris-Benedict as revised by Roza and Shizgal (1984), which gives the same man 1700.
BMR by weight at age 30
| Weight | Men, 175 cm (5 ft 9 in) | Women, 165 cm (5 ft 5 in) |
|---|---|---|
| 50 kg (110 lb) | 1449 kcal/day | 1220 kcal/day |
| 60 kg (132 lb) | 1549 kcal/day | 1320 kcal/day |
| 70 kg (154 lb) | 1649 kcal/day | 1420 kcal/day |
| 80 kg (176 lb) | 1749 kcal/day | 1520 kcal/day |
| 90 kg (198 lb) | 1849 kcal/day | 1620 kcal/day |
| 100 kg (220 lb) | 1949 kcal/day | 1720 kcal/day |
| 110 kg (243 lb) | 2049 kcal/day | 1820 kcal/day |
Mifflin-St Jeor results for the weight in kilograms, rounded to a whole calorie as the calculator shows them. Each extra kilogram adds 10 kcal a day, each extra centimeter of height adds 6.25, and each year of age takes off 5.
Daily calories by activity level for a BMR of 1643 kcal (man, 25, 70 kg, 170 cm)
| Activity level | Factor | Estimated daily calories |
|---|---|---|
| Sedentary (little or no exercise) | × 1.2 | 1971 kcal/day |
| Lightly active (exercise 1 to 3 days a week) | × 1.375 | 2258 kcal/day |
| Moderately active (exercise 3 to 5 days a week) | × 1.55 | 2546 kcal/day |
| Very active (hard exercise 6 to 7 days a week) | × 1.725 | 2833 kcal/day |
| Extra active (a physical job or training twice a day) | × 1.9 | 3121 kcal/day |
The calculator multiplies the unrounded BMR, 1642.5 kcal here, by each factor.
Methodology
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5 for men, or − 161 for women. Pounds are converted at 0.45359237 kg and inches at 2.54 cm. Estimated daily calories (TDEE) = BMR × activity factor: 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active, 1.9 extra active. The BMR is shown rounded to a whole calorie, and the unrounded figure is used for the multiplication. Harris-Benedict (Roza and Shizgal, 1984) = 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age for men, or 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age for women.
Frequently asked questions
- How many calories do I burn at rest?
- By the Mifflin-St Jeor equation, 10 kcal for each kilogram of body weight plus 6.25 for each centimeter of height, minus 5 for each year of age, then plus 5 for men or minus 161 for women. For a 30-year-old that is 1649 kcal a day for a 70 kg man of 175 cm and 1320 for a 60 kg woman of 165 cm.
- What is the difference between BMR and TDEE?
- BMR is the energy your body uses at rest. TDEE, total daily energy expenditure, adds movement: the calculator multiplies BMR by 1.2 for little or no exercise, rising to 1.9 for a physical job or training twice a day. For a BMR of 1643 that is 1971 to 3121 kcal a day.
- How accurate is the Mifflin-St Jeor equation?
- A 2005 systematic review found it the most reliable of four common equations: it came within 10% of measured resting metabolic rate in more people than the others. It still misses by more than 10% for some, and the review notes that older adults and US ethnic minorities were underrepresented in the studies. For a result of 1643 kcal, 10% is about 164 kcal either way. The Harris-Benedict option, revised by Roza and Shizgal in 1984, is quoted with a precision of 14% for normally nourished people; for the same man it gives 1700 kcal.
- Is BMR the same as RMR?
- The terms are often used for the same number. The 1990 Mifflin-St Jeor paper measured resting energy expenditure by indirect calorimetry in 498 healthy adults aged 19 to 78, so strictly the equation predicts resting metabolism. This calculator reports the result as BMR.
- Why is my BMR lower than a man’s, or lower than it was ten years ago?
- In the equation the constant is 166 kcal lower for women (−161 against +5), and each year of age subtracts 5 kcal. The same man at 35 instead of 25 gets 1593 kcal instead of 1643.
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