BMR Calculator
Fill in age, biological sex, weight and height above and the BMR calculator shows your basal metabolic rate in calories per day, updating as you type. It uses the Mifflin-St Jeor equation, works in kg and cm or lb and feet and inches, and runs entirely in your browser, so nothing you enter is uploaded.
How this BMR calculator works
There is no submit button. Work down the form and the Basal metabolic rate figure changes with every keystroke:
- Units: pick Metric (kg, cm) or Imperial (lb, ft/in). Switching converts what you already typed.
- Biological sex: the equation has a different constant for men and women.
- Age: whole years, from 15 to 120.
- Weight and Height: decimals are fine. In imperial, height is two boxes, feet and inches.
Until every field holds a usable value the result shows --. The figure is in kcal / day, rounded to a whole number.
BMR = 1,649 kcal/day
Woman, 25 years, 60 kg, 165 cm
BMR = 1,345 kcal/day
The Mifflin-St Jeor formula for men and women
Mifflin-St Jeor, published in 1990, is one of the most widely used equations for estimating resting calories. With weight in kilograms, height in centimetres and age in years:
Women: BMR = (10 × weight) + (6.25 × height) − (5 × age) − 161
For the same age, weight and height the two results differ by exactly 166 kcal a day. If you enter pounds and feet, the page first converts weight by dividing by 2.20462 and height by multiplying total inches by 2.54.
BMR calculator in kg and cm or lbs and feet
Use whichever units you know. A person who weighs 154 lb and stands 5 ft 9 in gets the same answer as someone entering 69.9 kg and 175.3 cm. On a phone the number keypad opens for each box, and a decimal comma works as well as a decimal point.
BMR vs RMR vs TDEE: what this number is, and isn't
BMR is what your body burns at complete rest. RMR is the same idea measured under looser conditions, so the two are close enough that an RMR calculator and a BMR calculator give the same answer. TDEE adds your daily movement on top, usually by multiplying BMR by an activity factor between roughly 1.2 and 1.9. This tool stops at BMR and applies no activity factor.
| Term | What it counts |
|---|---|
| BMR | Rest only, in a strict test setting |
| RMR | Rest only, in a looser test setting |
| TDEE | Rest plus movement, exercise and digestion |
How accurate is a BMR calculator?
Treat the result as a well-founded estimate, not a measurement. Mifflin-St Jeor typically lands within about 10 percent of a lab-measured resting rate for most healthy adults. Muscle mass, genetics, hormones and some medications can move your true figure, and the equation is less dependable for people under 18 and for very lean or very muscular bodies. It is a general reference, not medical advice.
Frequently asked questions
What is BMR?
BMR, or basal metabolic rate, is the number of calories your body burns in a day just to stay alive at complete rest: breathing, circulating blood, keeping organs working and holding body temperature. It does not include walking, exercise or digesting food. For most adults it makes up the biggest share of the calories they burn in a day.
How do I calculate BMR?
Use the Mifflin-St Jeor equation. For men it is (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5. For women it is the same sum minus 161 instead of plus 5. A 30-year-old man at 70 kg and 175 cm gets 1,649 kcal a day. This page does the sum and the pound, foot and inch conversion for you.
What is a good BMR for women and for men?
There is no good or bad BMR; it follows from your age, sex, weight and height, so a bigger or younger body burns more at rest. As a rough guide, adult women often land around 1,200 to 1,500 kcal a day and adult men around 1,500 to 1,900. Compare your number only with your own earlier results, not with someone else.
Is BMR the same as RMR?
Nearly. BMR is measured under strict lab conditions, fasted and fully rested. RMR, or resting metabolic rate, is measured under looser conditions and usually comes out a little higher. The Mifflin-St Jeor equation was built from resting measurements, so for everyday use the two terms mean the same number, and an RMR calculator gives the same answer as this one.
What is the difference between BMR and TDEE?
BMR is what you burn at rest. TDEE, or total daily energy expenditure, is BMR plus everything else: movement, exercise and digestion. TDEE is usually found by multiplying BMR by an activity factor, from about 1.2 for a desk job with little exercise to about 1.9 for very hard daily training. This page shows BMR only, with no activity factor applied.
How accurate is a BMR calculator?
It is an estimate. Mifflin-St Jeor is among the most accurate equations for healthy adults, and it typically lands within about 10 percent of a measured resting rate for most people. Muscle mass, genetics, hormones and medications all move the real figure. Results are less reliable for people under 18 and for very muscular or very lean bodies.
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