BMR Calculator
Find out how many calories your body burns at rest using the Mifflin-St Jeor formula.
This is an estimate only and not medical advice.
What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic life functions — breathing, circulation, cell production, and organ function — while completely at rest. It does not include the calories burned through movement, digestion, or exercise. Because BMR typically makes up 60-75% of total daily calorie burn for most adults, it's the foundation for building an accurate nutrition or weight-management plan.
How this calculator works
This calculator uses the Mifflin-St Jeor equation, which is widely regarded by dietitians and researchers as the most accurate BMR formula for modern populations (replacing the older Harris-Benedict equation). It factors in your sex, age, height, and weight: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. The breakdown below also estimates your calorie needs with light activity (BMR × 1.375) and moderate activity (BMR × 1.55), giving you a more realistic daily calorie target than resting metabolism alone.
Using your BMR
Your BMR is a starting point, not a finish line. Combine it with your actual activity level to estimate your Total Daily Energy Expenditure (TDEE), which is what most people should use when planning calorie intake for weight loss, maintenance, or muscle gain. This tool provides an estimate only and is not medical advice — consult a healthcare provider for personalized guidance.
Frequently Asked Questions
What is BMR and why does it matter?
BMR (Basal Metabolic Rate) is the number of calories your body burns just to keep you alive at complete rest — breathing, circulating blood, and running your organs. It matters because it's typically the largest component of your total daily calorie burn, making it the foundation for any calorie or weight-management plan.
What formula does this BMR calculator use?
This calculator uses the Mifflin-St Jeor equation, which research has shown to be more accurate for most modern adults than the older Harris-Benedict formula. It calculates BMR from your sex, age, height, and weight.
What's the difference between BMR and TDEE?
BMR is calories burned at complete rest. TDEE (Total Daily Energy Expenditure) adds in calories burned through daily movement, exercise, and digestion. TDEE is the number you should actually use when planning your calorie intake for weight loss, maintenance, or muscle gain.
Why is my BMR different from a friend's even at the same weight?
BMR depends on more than just weight — sex, age, height, and body composition (muscle vs. fat) all play a role. Muscle tissue burns more calories at rest than fat tissue, so two people with the same weight but different muscle mass can have noticeably different BMRs.
Does BMR decrease with age?
Yes. BMR generally declines with age, partly due to natural loss of muscle mass over time. Staying active and maintaining muscle through resistance training can help offset some of this age-related metabolic slowdown.
Should I eat exactly my BMR in calories to lose weight?
No — eating at or below your BMR isn't recommended, since that number doesn't include the energy you need for daily activity. Instead, use your BMR to estimate your TDEE, then create a moderate calorie deficit from that higher number for sustainable weight loss.
How can I increase my BMR?
Building lean muscle mass through resistance training is one of the most effective ways to raise your resting metabolism, since muscle tissue burns more calories at rest than fat tissue. Adequate sleep, sufficient protein intake, and avoiding extreme calorie restriction also help support a healthy metabolic rate.
Is this BMR calculator accurate?
The Mifflin-St Jeor formula used here is considered one of the most reliable equations for estimating BMR in the general population, but individual metabolism can still vary due to genetics, medical conditions, and body composition. This is an estimate only and not medical advice.