BMR and TDEE Calculator

What is BMR?

Basal Metabolic Rate (BMR) is the number of calories your body needs to perform essential functions at rest, such as breathing, blood circulation, cell production, and maintaining body temperature. It represents the minimum energy required to keep your body alive and functioning.

BMR accounts for approximately 60-75% of your total daily calorie expenditure and is influenced by several factors:

• Age: BMR decreases with age
• Gender: Men typically have higher BMR than women
• Weight: Higher body weight increases BMR
• Height: Taller individuals have higher BMR
• Body composition: More muscle mass increases BMR

BMR Formulas

This calculator uses two widely-accepted formulas to estimate BMR:

Mifflin-St Jeor Equation (Recommended)

The Mifflin-St Jeor equation is generally considered more accurate for modern lifestyles and is the recommended formula.

For Men:

For Women:

Harris-Benedict Equation

The Harris-Benedict equation is a classic formula developed in 1918 and revised in 1984. It tends to overestimate BMR by about 5% compared to Mifflin-St Jeor.

For Men:

For Women:

What is TDEE?

Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period, including all physical activity. TDEE is calculated by multiplying your BMR by an activity factor.

Activity Multipliers

• Sedentary (×1.2): Little to no exercise, desk job
• Lightly Active (×1.375): Light exercise 1-3 days/week
• Moderately Active (×1.55): Moderate exercise 3-5 days/week
• Very Active (×1.725): Hard exercise 6-7 days/week
• Extra Active (×1.9): Very hard exercise, physical job, or training 2x/day

How to Use This Calculator

1. Select your gender: Male or female
2. Enter your age: In years
3. Enter your weight: In kilograms
4. Enter your height: In centimeters
5. Select your activity level: Choose the option that best describes your typical week

The calculator will display:

• BMR from both formulas (Mifflin-St Jeor recommended)
• TDEE based on your activity level
• Calorie goals for weight loss, maintenance, and weight gain

Calorie Goals Explained

Weight Loss (-500 kcal/day)

Eating 500 calories below your TDEE typically results in approximately 0.5 kg (1 lb) of weight loss per week. This is considered a safe and sustainable rate.

Maintenance (TDEE)

Eating at your TDEE maintains your current weight, assuming your activity level remains consistent.

Weight Gain (+500 kcal/day)

Eating 500 calories above your TDEE typically results in approximately 0.5 kg (1 lb) of weight gain per week, ideal for muscle building when combined with strength training.

Practical Example

Scenario: 30-year-old male, 75 kg, 175 cm, moderately active

Mifflin-St Jeor BMR:

• BMR = (10 × 75) + (6.25 × 175) - (5 × 30) + 5
• BMR = 750 + 1093.75 - 150 + 5
• BMR ≈ 1,699 kcal/day

TDEE:

• TDEE = BMR × 1.55 (moderately active)
• TDEE = 1,699 × 1.55
• TDEE ≈ 2,633 kcal/day

Calorie Goals:

• Weight loss: 2,133 kcal/day
• Maintenance: 2,633 kcal/day
• Weight gain: 3,133 kcal/day

Important Considerations

Limitations

• Estimates only: BMR formulas provide estimates and may not be perfectly accurate for everyone
• Individual variation: Genetics, hormones, and medical conditions can affect actual BMR
• Body composition: The formulas don't account for muscle vs. fat ratio
• Metabolic adaptation: Long-term calorie restriction can lower BMR

Tips for Accuracy

1. Be honest about activity level: Overestimating leads to consuming too many calories
2. Track your results: Monitor weight changes over 2-4 weeks and adjust calories accordingly
3. Consider body composition: If you have high muscle mass, your actual BMR may be higher
4. Consult professionals: For personalized advice, consult a registered dietitian or nutritionist

When to Recalculate

Recalculate your BMR and TDEE when:

• You lose or gain significant weight (5+ kg)
• Your activity level changes substantially
• Every 6-12 months as you age

Additional Resources

For more accurate measurements, consider:

• Indirect calorimetry: Professional metabolic testing
• DEXA scan: Measures body composition for more accurate estimates
• Fitness tracker data: Long-term activity tracking can refine TDEE estimates

Remember that these calculations are starting points. Individual responses vary, so adjust based on your actual results and how you feel.