BMR Calculator
Calculate your Basal Metabolic Rate to understand how many calories your body needs at rest and at different activity levels.
How to Use
- Enter your age, gender, weight, and height.
- Click "Calculate BMR" to see your basal metabolic rate.
- Review your daily calorie needs at each activity level.
- Use these numbers to plan your nutrition and fitness goals.
How It Works
BMR is the number of calories your body burns at complete rest to maintain basic life functions like breathing and circulation. This calculator uses 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. Your BMR is then multiplied by activity factors ranging from 1.2 (sedentary) to 1.9 (extra active) to estimate your Total Daily Energy Expenditure (TDEE).
What Is Basal Metabolic Rate?
Basal Metabolic Rate (BMR) is the number of calories your body burns each day just to keep you alive. Even when you're lying in bed doing absolutely nothing, your body is using energy to power your heart, lungs, brain, liver, kidneys, and every other organ. For most people, BMR accounts for 60 to 75 percent of total daily calorie expenditure, making it by far the largest component of your energy budget.
BMR is influenced by several factors. Larger bodies burn more calories at rest than smaller ones. Men generally have higher BMRs than women because they tend to carry more muscle mass. Younger people burn more at rest than older adults because metabolism naturally slows with age. Understanding your BMR is the first step toward building an effective nutrition plan. Once you know how many calories your body needs at rest, you can layer on your activity level to determine your Total Daily Energy Expenditure (TDEE), which is the actual number of calories you should be eating each day to meet your goals.
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR is the calories your body burns at complete rest, while TDEE includes all calories burned throughout the day including physical activity, digestion, and daily movement. Your TDEE is always higher than your BMR. To estimate TDEE, your BMR is multiplied by an activity factor that ranges from 1.2 (sedentary) to 1.9 (extremely active).
Can I increase my BMR?
The most effective way to raise your BMR is to build muscle through resistance training. Muscle tissue burns more calories at rest than fat tissue, so the more lean mass you carry, the higher your baseline metabolism will be. Staying well-hydrated, getting enough sleep, and eating adequate protein also support a healthy metabolic rate.
Why does BMR decrease with age?
As you age, you naturally lose muscle mass in a process called sarcopenia, which typically begins in your 30s. Since muscle is metabolically active tissue, less of it means fewer calories burned at rest. Regular strength training can significantly slow this decline and help maintain a higher BMR well into older age.
Should I eat below my BMR to lose weight?
Eating below your BMR for extended periods is generally not recommended. Your body needs that baseline energy to function properly, and chronically undereating can lead to muscle loss, nutrient deficiencies, and metabolic slowdown. Instead, create a moderate deficit below your TDEE while keeping intake above or near your BMR.
Is the Mifflin-St Jeor equation the best BMR formula?
The Mifflin-St Jeor equation is considered the most accurate BMR formula for the general population, according to the American Dietetic Association. It was developed in 1990 using modern data and tends to give more accurate results than older formulas like Harris-Benedict. However, individual variation means any formula is an estimate rather than an exact measurement.
Example Calculation
Consider a 25-year-old woman who weighs 140 lbs (63.5 kg) and is 5'6" tall (167.6 cm). Using the Mifflin-St Jeor equation for women: BMR = 10 × 63.5 + 6.25 × 167.6 - 5 × 25 - 161 = 635 + 1,048 - 125 - 161 = 1,397 calories/day. If she exercises 3 to 5 days per week (moderately active, factor 1.55), her TDEE would be 1,397 × 1.55 = approximately 2,165 calories/day. That's her maintenance level. For gradual weight loss, she would aim for about 1,665 calories per day.