BMR Calculator
Enter your height, weight, age, and sex to calculate the calories your body burns at complete rest.
What Is Basal Metabolic Rate?
Your Basal Metabolic Rate (BMR) is the number of calories your body burns every day just to keep you alive — heart beating, lungs breathing, kidneys filtering, and cells regenerating. It accounts for 60–75% of total daily calorie expenditure for most sedentary people, making it the largest single component of your energy budget.
BMR is influenced by body composition, age, sex, and height. People with more lean muscle mass have higher BMRs because muscle tissue is metabolically more active than fat tissue. Men typically have higher BMRs than women due to greater average muscle mass and higher testosterone levels.
The Mifflin-St Jeor Formula
This calculator uses the Mifflin-St Jeor equation, published in 1990 and validated as the most accurate predictive formula for most adults:
For example, a 35-year-old man who weighs 80 kg and is 180 cm tall: BMR = (10×80) + (6.25×180) − (5×35) + 5 = 800 + 1,125 − 175 + 5 = 1,755 kcal/day.
BMR by Age and Sex (Reference)
| Age | Male Avg BMR | Female Avg BMR |
|---|---|---|
| 20–29 | 1,800–1,900 kcal | 1,450–1,550 kcal |
| 30–39 | 1,750–1,850 kcal | 1,400–1,500 kcal |
| 40–49 | 1,700–1,800 kcal | 1,350–1,450 kcal |
| 50–59 | 1,650–1,750 kcal | 1,300–1,400 kcal |
| 60+ | 1,550–1,700 kcal | 1,250–1,350 kcal |
Averages based on 70 kg / 165 cm male and 60 kg / 163 cm female at each age bracket.
Frequently Asked Questions
What is Basal Metabolic Rate (BMR)?
BMR is the number of calories your body needs to maintain basic physiological functions — breathing, circulation, cell production, and organ function — while completely at rest. It represents the minimum energy your body requires to stay alive.
Which BMR formula does this calculator use?
This calculator uses the Mifflin-St Jeor equation, which is considered the most accurate formula for the general population. A 2005 study published in the Journal of the American Dietetic Association found it to be within 10% of measured resting metabolic rate for most people.
How is BMR different from TDEE?
BMR is your calorie burn at complete rest. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor to account for exercise and daily movement. Use our TDEE Calculator to find your full daily calorie needs.
Can I use BMR to lose weight?
Yes — but you shouldn't eat below your BMR. Your BMR is the minimum your body needs to function. Eating below it can cause muscle loss, metabolic slowdown, and nutrient deficiencies. Instead, use TDEE as your baseline and create a modest deficit of 300–500 kcal/day.
Does BMR change over time?
Yes. BMR decreases with age (roughly 1–2% per decade after 20) and increases with muscle mass. Dieting can temporarily lower BMR. Building muscle through resistance training is one of the most effective ways to raise your BMR long-term.