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BMR Calculator

Calculate your Basal Metabolic Rate (BMR) and daily energy expenditure (TDEE) by activity level using the Mifflin-St Jeor equation.

Input Information

Result

Calculate the energy your body burns in a day!

Basal Metabolic Rate (BMR) is the minimum energy your body needs to sustain life. It is the energy used by all unconscious bodily functions—heartbeat, breathing, temperature regulation, cell renewal— and knowing it lets you scientifically plan an appropriate daily calorie intake.

Multiplying BMR by an activity factor that reflects your daily activity gives Total Daily Energy Expenditure (TDEE). Based on TDEE you can plan diets for weight maintenance, loss, or gain, making it useful for dieting or building muscle.

This calculator uses the Mifflin-St Jeor equation, widely regarded as the most accurate today. Enter your sex, age, height, and weight, and it calculates TDEE by activity level all at once. It is an essential health tool for anyone—office workers, students, those starting to exercise.

Term Glossary

BMR (Basal Metabolic Rate)
The minimum energy spent on heartbeat, breathing, cell renewal, etc. to sustain life. It is the calories burned at rest and the baseline for diet planning.
TDEE (Total Daily Energy Expenditure)
Your total daily calorie expenditure, found by multiplying BMR by an activity factor reflecting daily activity and exercise. Used for weight maintenance/loss goals.
Mifflin-St Jeor Equation
A formula estimating BMR using sex, age, height, and weight as variables. Widely used in modern nutrition as the most accurate BMR calculation method.

📋 How to Use

  1. 1
    Select sex → choose Male or Female
  2. 2
    Enter body info → input height (cm), weight (kg), and age (years)
  3. 3
    Select activity level → choose your daily activity level (sedentary to extra active)
  4. 4
    View results → check your Basal Metabolic Rate (BMR) and daily calorie expenditure (TDEE)

📝 Worked Examples

Example 1: 30-year-old male, 175cm, 70kg, moderate activity

BMR = 10×70 + 6.25×175 - 5×30 + 5 = 1683 kcalTDEE = 1683 × 1.55 = 2609 kcal

Example 2: 25-year-old female, 160cm, 55kg, light activity

BMR = 10×55 + 6.25×160 - 5×25 - 161 = 1304 kcalTDEE = 1304 × 1.375 = 1793 kcal

Mifflin-St Jeor equation and TDEE

Step 1: Calculate BMR

The Mifflin-St Jeor equation is widely used as the most accurate BMR estimation formula in modern nutrition.

Male: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(yr) + 5Female: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(yr) - 161

Step 2: Calculate TDEE

TDEE = BMR × activity factor

  • 1.2: Sedentary (almost no exercise)
  • 1.375: Light activity (1~3 times/week)
  • 1.55: Moderate activity (3~5 times/week)
  • 1.725: Active (6~7 times/week)
  • 1.9: Very active (2+ times/day)

💡 Key tips for using BMR

1. Raise your BMR with strength training

More muscle means a higher BMR. Increasing skeletal muscle through regular strength training burns more calories even at rest, helping with weight management.

2. Don't eat below your BMR

Eating below BMR can lower your metabolism and make weight loss harder. For healthy loss, reducing TDEE by 300~500kcal is appropriate.

3. Choose a realistic activity factor

Picking a high activity factor without actually exercising overstates TDEE, leading to unintended overeating—choose based on your real activity level.

4. Be aware of age-related metabolic changes

After your 30s, BMR tends to drop about 3~5% every 10 years. Age-appropriate exercise and diet adjustment are essential for long-term health.

5. Use it to break diet plateaus

A diet plateau occurs as your body adapts to a new metabolic rate. Recalculating BMR and TDEE and adjusting your diet accordingly helps break through it.

6. Get enough protein

To maintain muscle while dieting, aim for 1.2~1.6g of protein per kg of body weight. Protein has a high energy cost to digest and increases satiety.

7. Recalculate regularly

Whenever your weight or activity level changes, recalculating BMR and TDEE and updating your diet plan is effective.

❓ Frequently Asked Questions

QWhat is the difference between BMR and TDEE?

BMR is calories burned at complete rest; TDEE includes all daily activities (exercise, walking, digestion etc.).

QWhy is the Mifflin-St Jeor equation more accurate?

Research shows Mifflin-St Jeor most closely matches measured resting metabolic rate in ~70% of people.

QHow do I determine my activity level?

Sedentary: desk job no exercise; Light: exercise 1-3 days/week; Moderate: 3-5 days; Very active: 6-7 days hard exercise; Extra active: athlete-level.

QShould I eat below my BMR to lose weight?

No. Eating below BMR can slow metabolism, cause muscle loss, and trigger nutritional deficiencies. Sustainable deficit is 300-500 kcal below TDEE.

QDoes metabolic rate decrease with age?

BMR decreases ~1-2% per decade after 20, mainly due to muscle mass loss. Resistance training can counteract this decline.

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