Your basal metabolic rate is what the body burns doing nothing at all. Breathing, pumping blood, maintaining temperature, repairing tissue. For most people it is sixty to seventy percent of everything burned in a day.
Fill every field to see your result.
Everything is calculated in your browser. Nothing is sent or stored. This is a reference figure, not a diagnosis.
The formula behind the number
This calculator uses the Mifflin-St Jeor equation, which is the one most widely validated against measured resting metabolism.
- Men: 10 x weight in kg, plus 6.25 x height in cm, minus 5 x age, plus 5
- Women: the same, minus 161 instead of plus 5
A man of 72 kg and 165 cm aged 38 gets 720 plus 1,031 minus 190 plus 5, which is about 1,570 kcal at complete rest.
BMR, RMR and TDEE are not the same thing
BMR is measured after an overnight fast, lying still, in a temperature-controlled room. Resting metabolic rate is the same idea measured under looser conditions, and usually reads a little higher. Total daily energy expenditure is BMR multiplied by an activity factor, and that is the number to use when setting intake. If you want intake directly, use the daily calorie and TDEE calculator instead.
Why your real BMR can sit away from the estimate
The equation predicts an average for your height, weight, age and sex. Two people with identical measurements can differ by a few hundred calories, and muscle mass is the usual reason, since muscle costs more to maintain than fat. Thyroid function moves it too. Long periods of heavy restriction lower it, which is part of why intake that worked at the start of a diet stops working later.
How to use the number
Do not eat at your BMR. It is a floor, not a target, and eating at it over weeks tends to cost muscle. Use the activity rows above as a starting intake, hold it for two to three weeks, then adjust against what the scale and the tape actually do. The equation gives you a place to start, not an answer.
When the number does not add up
If weight will not move at an intake well below the estimate, the useful next step is measurement rather than further cutting. Thyroid function, fasting insulin and body composition explain most of these cases between them. A thyroid function test and fasting insulin with HOMA-IR cover the two most common, and a body composition test shows how much of your weight is muscle. To go through it with a doctor, book a consultation.
Every iLIV guide is written and reviewed under our editorial standards, and each one carries the name of the reviewing doctor together with their MMC registration number.
