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BMR Calculator

Calculate your Basal Metabolic Rate (BMR) to understand how many calories your body needs at rest. Uses Mifflin-St Jeor and Harris-Benedict equations.

A BMR calculator estimates the number of calories your body burns at complete rest, which is essential for setting accurate calorie targets for weight management.

Select your unit system (imperial or metric), gender, and enter your age, weight, and height. Click Calculate to see your Basal Metabolic Rate - the number of calories your body burns at complete rest. The results also show estimated daily calorie needs for different activity levels.

Examples

30-Year-Old Male

A 30-year-old male, 154 lbs (70 kg), 5'7" (170 cm) has a Mifflin-St Jeor BMR of approximately 1,597 kcal/day. With moderate activity (3-5 days/week), daily needs rise to about 2,475 kcal.

25-Year-Old Female

A 25-year-old female, 130 lbs (59 kg), 5'4" (163 cm) has a Mifflin-St Jeor BMR of approximately 1,348 kcal/day. With light activity (1-3 days/week), daily needs rise to about 1,853 kcal.

Frequently Asked Questions

What is Basal Metabolic Rate (BMR)?
BMR is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, cell production, and nutrient processing while at complete rest. It represents the minimum energy your body requires to function.
What is the difference between BMR and TDEE?
BMR measures calories burned at complete rest, while TDEE (Total Daily Energy Expenditure) includes BMR plus all calories burned through daily activities and exercise. TDEE is your BMR multiplied by an activity factor.
Which BMR formula is more accurate?
The Mifflin-St Jeor equation, published in 1990, is generally considered the most accurate for most people. The Harris-Benedict equation (revised in 1984) tends to overestimate calorie needs slightly. Both are shown here for comparison.
How can I increase my BMR?
Building lean muscle mass through strength training is the most effective way to increase BMR, since muscle tissue burns more calories at rest than fat tissue. Staying well-hydrated, getting adequate sleep, and eating enough protein also support a healthy metabolism.
Why does BMR decrease with age?
BMR decreases with age primarily due to the gradual loss of muscle mass (sarcopenia) and hormonal changes. After age 20, BMR decreases by approximately 1-2% per decade. Regular exercise and strength training can help slow this decline.

Related Information

Your BMR accounts for roughly 60-75% of your total daily calorie expenditure. The remaining calories are burned through physical activity (15-30%) and the thermic effect of food (about 10%). Understanding your BMR is the foundation for any weight management plan, whether your goal is to lose, maintain, or gain weight.

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Quick Tips

  • •Use your BMR as a starting point and adjust based on real-world weight changes over 2-3 weeks.
  • •Building lean muscle through strength training is the most effective way to raise your BMR over time.
  • •Never eat below your BMR for extended periods without medical supervision.

A BMR calculator estimates the number of calories your body burns at complete rest, which is essential for setting accurate calorie targets for weight management.

How to Use This Calculator

Select your unit system (imperial or metric), gender, and enter your age, weight, and height. Click Calculate to see your Basal Metabolic Rate - the number of calories your body burns at complete rest. The results also show estimated daily calorie needs for different activity levels.

Understanding the Formula

This calculator uses the Mifflin-St Jeor equation, widely considered the most accurate BMR formula. For men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5. For women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161. The Harris-Benedict equation is also shown for comparison.

Examples

30-Year-Old Male

A 30-year-old male, 154 lbs (70 kg), 5'7" (170 cm) has a Mifflin-St Jeor BMR of approximately 1,597 kcal/day. With moderate activity (3-5 days/week), daily needs rise to about 2,475 kcal.

25-Year-Old Female

A 25-year-old female, 130 lbs (59 kg), 5'4" (163 cm) has a Mifflin-St Jeor BMR of approximately 1,348 kcal/day. With light activity (1-3 days/week), daily needs rise to about 1,853 kcal.

Frequently Asked Questions

What is Basal Metabolic Rate (BMR)?

BMR is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, cell production, and nutrient processing while at complete rest. It represents the minimum energy your body requires to function.

What is the difference between BMR and TDEE?

BMR measures calories burned at complete rest, while TDEE (Total Daily Energy Expenditure) includes BMR plus all calories burned through daily activities and exercise. TDEE is your BMR multiplied by an activity factor.

Which BMR formula is more accurate?

The Mifflin-St Jeor equation, published in 1990, is generally considered the most accurate for most people. The Harris-Benedict equation (revised in 1984) tends to overestimate calorie needs slightly. Both are shown here for comparison.

How can I increase my BMR?

Building lean muscle mass through strength training is the most effective way to increase BMR, since muscle tissue burns more calories at rest than fat tissue. Staying well-hydrated, getting adequate sleep, and eating enough protein also support a healthy metabolism.

Why does BMR decrease with age?

BMR decreases with age primarily due to the gradual loss of muscle mass (sarcopenia) and hormonal changes. After age 20, BMR decreases by approximately 1-2% per decade. Regular exercise and strength training can help slow this decline.

Assumptions & Limitations

  • The Mifflin-St Jeor equation is based on population averages and may not reflect individual metabolic variation.
  • Does not account for body composition — two people at the same weight can have very different BMRs depending on muscle mass.
  • Activity multipliers are broad categories and may not precisely match your actual daily energy expenditure.

Related Information

Your BMR accounts for roughly 60-75% of your total daily calorie expenditure. The remaining calories are burned through physical activity (15-30%) and the thermic effect of food (about 10%). Understanding your BMR is the foundation for any weight management plan, whether your goal is to lose, maintain, or gain weight.