BMR Calculator
Work out the calories your body uses at complete rest, and what each activity level adds.
BMR Calculator
Calories your body burns at rest
1,618
- If you barely exercise1,941
- If you exercise 3 to 5 days a week2,507
- If you exercise hard daily3,073
Works out in your browser. Nothing you type is sent anywhere.
In short: BMR Calculator
For the details entered, the basal rate is about 1,618 calories a day by the Mifflin-St Jeor equation. With almost no exercise that becomes roughly 1,941 a day, with exercise three to five days a week about 2,507, and with hard daily training around 3,073.
What is BMR?
Basal metabolic rate is the energy your body uses at complete rest, to keep the heart, lungs, brain and the rest of it working.
How is BMR calculated?
The Mifflin-St Jeor equation multiplies weight in kilograms by ten, adds height in centimetres times six and a quarter, subtracts age times five, and then adds a constant that differs between men and women. The Harris-Benedict equation uses different constants and usually reads slightly higher.
- BMRcalories used a day at complete rest
- wweight in kilograms
- hheight in centimetres
- aage in years
- sthe constant for your sex
A worked example
| Sex | Male |
|---|---|
| Age (years) | 30 |
| Height (cm) | 170 |
| Weight (kg) | 70 |
| Formula | Mifflin-St Jeor |
| Result | |
| Calories your body burns at rest | 1,618 |
| If you barely exercise | 1,941 |
| If you exercise 3 to 5 days a week | 2,507 |
| If you exercise hard daily | 3,073 |
Every figure in this table is produced by the same calculation the tool above runs.
How to use this BMR calculator
- Enter your sex, age, height and weight.
- Leave the equation as Mifflin-St Jeor unless you need the other.
- Read the resting figure first.
- Then read the activity level that matches your week.
Questions people ask
Which equation should I use?
Mifflin-St Jeor is the more recent of the two and is generally considered the more accurate for most adults, which is why it is the default here. Harris-Benedict is older and still widely quoted, and usually reads a little higher. Both are estimates built from population averages.
How accurate is a BMR estimate?
It is an average for people of your size and age, and an individual can sit noticeably above or below it. Muscle mass, thyroid function and genetics all move it. Treat it as a starting point and adjust from what actually happens to your weight.
What is the difference between BMR and daily calories?
BMR is what you burn lying still all day; daily needs add everything else you do, which is why the activity figures here are considerably higher. The multiplier for your activity level is how that is estimated. The calorie tool takes it further and splits the result into protein, carbohydrate and fat.
Should I eat less than my BMR to lose weight?
Generally not without medical supervision, because sustained eating below the resting rate is hard to maintain and can cost you muscle. A moderate deficit against your daily needs is the usual advice. Speak to a doctor or a dietitian before anything more aggressive.
Accuracy and sources
For general information. Not medical advice.
Checked by the Daytoolz team on 16 October 2026. How we check our tools.
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