Use the Mifflin-St Jeor equation
For men: BMR = 10 × weight in kg + 6.25 × height in cm – 5 × age in years + 5
For women: BMR = 10 × weight in kg + 6.25 × height in cm – 5 × age in years – 161
Measure weight in kilograms
Measure height in centimeters
Use age in years
Calculate the result in calories per day
Use a BMR calculator if you want a quick estimate
Recalculate after major changes in weight, age, or body composition