By Zencalcy Editorial TeamLast reviewed About us
Basal metabolic rate is the energy your body spends on breathing, circulation, cell repair and other basic functions at rest. The Mifflin-St Jeor equation is one of the most widely used ways to estimate it from sex, age, height and weight. This calculator returns a daily calorie figure and shows each part of the arithmetic.
Daily basal metabolic rate from the Mifflin-St Jeor equation.
Men: BMR = 10w + 6.25h - 5a + 5 Women: BMR = 10w + 6.25h - 5a - 161
w is weight in kilograms, h is height in centimetres and a is age in years. The equation predicts resting energy for adults and does not include exercise, digestion or thermoregulation, so it is always lower than total daily energy expenditure.
| Symbol | Meaning |
|---|---|
| w | Body weight in kilograms. |
| h | Standing height in centimetres. |
| a | Age in years. |
| BMR | Basal metabolic rate in kilocalories per day. |
BMR = 10 x 80 + 6.25 x 180 - 5 x 30 + 5 = 800 + 1125 - 150 + 5 = 1780 kcal per day. A 60 kg woman at 165 cm and 30 years gives 600 + 1031.25 - 150 - 161 = 1320.25, which rounds to 1320.3 kcal per day.
A predicted BMR is a statistical starting point, not a measurement of your metabolism. Two people with identical inputs can differ because of body composition, thyroid status, medication, diet history and genetics. The useful move is to treat the number as a hypothesis. Eat and move consistently for two or three weeks, track your weight at the same time of day, and compare the average trend with what the estimate predicted. If your weight is stable on a planned intake, your real maintenance is close to that intake regardless of what any equation says. If it is drifting, adjust by a modest amount rather than rewriting the whole plan. This feedback loop is more informative than repeatedly recalculating a formula that cannot see your body.
Continue with the Harris-Benedict Calculator, Katch-McArdle Calculator, or the RMR Calculator (Resting Metabolic Rate) — or browse more dietary tools and all health calculators.
Also see the Calorie Calculator, TDEE Calculator and the Macro Calculator.
BMR is measured under strict resting conditions, often after an overnight fast and in a neutral thermal environment. RMR is measured under looser conditions and is usually slightly higher. In practice the two terms are often used interchangeably for daily estimates.
Energy and nutrient estimates are population guidance, not personal prescriptions. Actual needs vary with body composition, medical conditions, medication, pregnancy and activity. Values are rounded and should be discussed with a registered dietitian or clinician when used to plan treatment.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
Content updated: September 2026