Health

BMR Calculator

Estimate how many calories your body burns at complete rest using the Mifflin-St Jeor equation.

Enter your details above to calculate your BMR.

Advertisement

BMR Formula (Mifflin-St Jeor)

Male

BMR = 10×kg + 6.25×cm − 5×age + 5

Female

BMR = 10×kg + 6.25×cm − 5×age − 161

What is BMR?

Basal Metabolic Rate (BMR) is the amount of energy your body expends to maintain vital functions while you are awake but completely at rest — things like keeping your heart beating, lungs breathing, and body temperature regulated. It typically accounts for 60–75% of total daily calorie expenditure.

Knowing your BMR is the starting point for any nutrition or weight management plan. Multiply it by an activity factor to get your TDEE, then adjust your intake above or below that number to gain or lose weight at a controlled pace.

Frequently asked questions

What is Basal Metabolic Rate (BMR)?
BMR is the number of calories your body needs to sustain essential functions — breathing, circulation, and cell production — while you are completely at rest. It represents the minimum energy your body requires to stay alive without any physical activity.
Which formula does this calculator use?
This calculator uses the Mifflin-St Jeor equation, which is widely regarded as the most accurate method for estimating BMR in the general population. For men: BMR = 10×kg + 6.25×cm − 5×age + 5. For women: BMR = 10×kg + 6.25×cm − 5×age − 161.
What is the difference between BMR and TDEE?
BMR is your calorie need at complete rest, while Total Daily Energy Expenditure (TDEE) multiplies BMR by an activity factor to account for movement throughout the day. TDEE is the actual number of calories you need to maintain your current weight.
Can I use BMR to plan a diet?
BMR alone is not sufficient for diet planning because it assumes zero activity. To set a calorie goal, first calculate your TDEE (BMR × activity multiplier) and then create a deficit below that number — typically 250–500 kcal/day for gradual, sustainable weight loss.
Does BMR change over time?
Yes. BMR decreases with age due to muscle loss, drops significantly during prolonged calorie restriction, and changes with shifts in body composition. Strength training helps preserve muscle mass, which keeps BMR higher as you age.
How accurate is the Mifflin-St Jeor equation?
Studies show the Mifflin-St Jeor formula predicts resting energy expenditure within about 10% for most adults, making it the preferred formula in clinical nutrition settings. Individual results can vary based on genetics and body composition.

Related calculators