What Is BMR? Basal Metabolic Rate Explained
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to keep you alive — powering your heart, lungs, brain, and cells. It accounts for the majority of your daily calorie burn and forms the base of your total daily energy expenditure.
See how many calories you burn at complete rest.
BMR vs Resting Metabolic Rate
BMR is measured under strict conditions: fully rested, fasted, and at a comfortable temperature. Resting Metabolic Rate (RMR) is a slightly looser, more practical version measured under normal resting conditions. The two are close enough that the terms are often used interchangeably in everyday fitness contexts.
How BMR Is Calculated
The most accurate widely used formula is the Mifflin-St Jeor equation:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Our BMR calculator applies this instantly. For a deeper dive, see our Mifflin-St Jeor guide.
See how many calories you burn at complete rest.
What Affects Your BMR
- Muscle mass — more muscle means a higher BMR.
- Body size — larger bodies burn more at rest.
- Age — BMR declines gradually with age, largely due to muscle loss.
- Sex — men usually have higher BMR due to more lean mass.
- Genetics and hormones — thyroid function plays a meaningful role.
How to Use Your BMR
BMR alone isn't your calorie target — you'd never want to eat at it. Instead, multiply it by an activity factor to get your TDEE, then set your intake relative to that. Knowing your BMR also explains why crash diets fail: eat far below it for too long and your body adapts by conserving energy.
Frequently Asked Questions
+What's the difference between BMR and TDEE?
BMR is calories burned at rest; TDEE is BMR plus digestion, daily movement, and exercise. TDEE is always higher and is what you base calorie goals on.
+Should I eat at my BMR to lose weight?
No. Eating at or below BMR for long periods is unsustainable and can slow your metabolism. Base your deficit on TDEE instead.
+Can I increase my BMR?
Somewhat — building muscle through resistance training raises BMR over time. The effect is modest but real and compounds with daily activity.
Conclusion
BMR is the calorie cost of simply being alive and the foundation of every nutrition plan. Calculate it, build your TDEE on top of it, and use it to set realistic, sustainable calorie goals.
See how many calories you burn at complete rest.