Estimate your basal metabolic rate (BMR), the calories your body burns at complete rest to keep you alive, using the Mifflin-St Jeor equation.
What is BMR?
Your basal metabolic rate is the energy your body uses at rest for breathing, circulation, temperature control and cell repair. It is usually the largest part of your daily calorie burn, often 60% to 70% for people who are not very active.
The Mifflin-St Jeor equation
This calculator uses the Mifflin-St Jeor equation, which research has found to be among the more accurate formulas for most adults:
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Worked example
A 35-year-old woman who is 5 ft 5 in (165.1 cm) and weighs 154 lb (69.9 kg) has a BMR of about 1,394 calories a day. With moderate exercise, her total daily energy use would be roughly 1,394 × 1.55 = 2,161 calories.
What affects BMR?
- Body size: larger bodies need more energy.
- Muscle mass: muscle burns more energy than fat at rest, so strength training can help a little.
- Age: BMR tends to decline gradually with age, partly due to muscle loss.
- Sex: men usually have a higher BMR because of greater average muscle mass.
- Genetics, hormones and health conditions also play a role, which is why any formula is only an estimate.
BMR versus TDEE
BMR is calories at rest. Your total daily energy expenditure (TDEE) adds everything else: walking, exercise and digesting food. To plan how much to eat, use TDEE. See the TDEE calculator.
Frequently asked questions
Should I eat fewer calories than my BMR?
Generally no, unless supervised by a professional. Eating well below your BMR for long periods can be hard to sustain and may not provide enough nutrition.
How accurate is the estimate?
For most people it is within about 10%, but individual results vary. Track your weight over a few weeks and adjust.
Related tools
These calculators give estimates for healthy adults based on published formulas. They are not medical advice. Talk to a doctor or registered dietitian before making major changes to your diet or exercise, especially if you are pregnant, under 18 or have a health condition.