BMR calculator.
Find your basal metabolic rate, the calories your body burns at rest, using the Mifflin-St Jeor equation. Then see roughly how many calories you burn a day at different activity levels.
Your details
LiveBMR is your at-rest burn. The rows show total daily calories once activity is added. Switch units any time.
Basal metabolic rate
1,780
calories per day at rest
Estimates from a population formula; individual metabolism varies. For medical or weight advice, see a professional. Calculations run in your browser; nothing is stored.
How it works
Calories at complete rest
Your BMR is the energy your body uses just to keep going: breathing, circulation, brain function and keeping warm. The Mifflin-St Jeor equation estimates it from your sex, age, height and weight, and is one of the most accurate simple formulas in use.
A 30-year-old man who is 180 cm and 80 kg has a BMR of about 1,780 calories. Multiply that by an activity factor and you get your total daily burn, shown in the rows on the right.
The full guide
The complete BMR guide.
What basal metabolic rate is, how it is calculated, and how to turn it into a daily calorie target.
What is BMR?
Basal metabolic rate is the number of calories your body would burn in a day if you did nothing but rest. It is the largest part of most people’s daily energy use, typically 60 to 70 percent, with activity and digestion making up the rest.
Knowing your BMR is the starting point for any calorie plan, because everything else is added on top of it.
The Mifflin-St Jeor equation
This calculator uses Mifflin-St Jeor, which research has found more accurate than older formulas for most people. For men it is ten times weight in kilograms, plus 6.25 times height in centimetres, minus five times age, plus five. For women the final term is minus 161 instead of plus five.
From BMR to daily calories
To estimate total daily calories, multiply your BMR by an activity factor: about 1.2 if you are sedentary, 1.375 for light activity, 1.55 for moderate, 1.725 for very active, and 1.9 for extremely active. The rows on the right show three of these levels for you.
That total is roughly the calories needed to maintain your current weight.
What affects your BMR
Muscle burns more at rest than fat, so more lean mass raises BMR. It also tends to fall with age and is affected by sex, body size, genetics and some medical conditions. Crash dieting can lower it, which is one reason very low-calorie diets often stall.
Using your BMR
Use BMR as the foundation of a plan, not a daily target on its own, since eating only your BMR while active would leave you in a large deficit. For a calorie goal that includes your activity, use the calorie calculator, which builds on the same equation.
The formula
The engine
at idle.
Mifflin-St Jeor estimates resting calories from sex, age, height and weight. Activity is added on top to get your daily total.
Try the calorie calculator ›# Mifflin-St Jeor (men)
BMR = 10·kg + 6.25·cm − 5·age + 5
# women
BMR = 10·kg + 6.25·cm − 5·age − 161
# daily calories
total = BMR × activity factorQuestions
BMR questions.
What is BMR?
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Basal metabolic rate is the calories your body burns at complete rest to keep its basic functions going. It is usually the biggest part of your daily energy use.
How is BMR calculated?
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This calculator uses the Mifflin-St Jeor equation, which takes your sex, age, height and weight. For men it is 10 times weight in kg plus 6.25 times height in cm minus 5 times age plus 5; for women the last term is minus 161.
How do I turn BMR into daily calories?
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Multiply your BMR by an activity factor, from about 1.2 for sedentary to 1.9 for extremely active. The result is roughly the calories needed to maintain your weight, shown in the rows.
Why is my BMR different from someone the same weight?
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BMR depends on more than weight. Age, sex, height and especially muscle mass all change it, so two people of the same weight can have different resting burns.
Is this BMR calculator free and private?
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Yes. It is completely free with no sign-up, and every calculation runs locally in your browser, so nothing you enter is stored or sent anywhere.
About the developer
Jean Borg
Jean builds and maintains every calculator on freecalculators.pro from Malta. The BMR calculator uses the Mifflin-St Jeor equation and is provided for general information, not medical advice.