Basal Metabolic Rate (BMR) Calculator

Calculate your Basal Metabolic Rate using the Mifflin-St Jeor equation.

How to Calculate BMR

Your Basal Metabolic Rate is calculated using the Mifflin-St Jeor equation with gender-specific formulas:

\[\text{BMR} = 10 \times \text{weight(kg)} + 6.25 \times \text{height(cm)} - 5 \times \text{age(y)} + \text{constant}\]

Where the constant is:

  • For Men: +5
  • For Women: -161

Calculate Your BMR

Gender

Male

Age

30

Weight

70 kg

Height

175 cm

BMR: 1,750 calories/day

Male
BMR = 10×w + 6.25×h - 5×a + 5
Female
BMR = 10×w + 6.25×h - 5×a - 161
kg
cm
Sedentary (little/no exercise)
BMR × 1.2
Lightly Active (exercise 1-3 days/week)
BMR × 1.375
Moderately Active (exercise 3-5 days/week)
BMR × 1.55
Very Active (hard exercise 6-7 days/week)
BMR × 1.725
Extremely Active (very hard exercise, physical job)
BMR × 1.9

Your BMR Results

0
0
calories per day

BMR Calculation Breakdown

Weight Component: 0 cal
Height Component: 0 cal
Age Component: 0 cal
Gender Constant: 0 cal
Basal Metabolic Rate: 0 cal
Total Daily Energy Expenditure (TDEE)
BMR × Activity Factor: 0 cal
Weight Loss (500 cal deficit): 0 cal
Weight Gain (500 cal surplus): 0 cal

Calorie Goals Based on Your BMR

Daily calorie targets for your goals:

  • Maintenance: 0 calories/day
  • Mild Weight Loss: 0 calories/day
  • Moderate Weight Loss: 0 calories/day
  • Mild Weight Gain: 0 calories/day

BMR Optimization Tips

Based on your BMR of 0 calories/day:

  • Build muscle through strength training to increase your BMR
  • Get adequate sleep to maintain healthy metabolism
  • Stay hydrated to support metabolic processes
  • Include protein-rich foods in your diet

Understanding BMR

What is BMR?

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to maintain basic physiological functions like breathing, circulation, and cell production. The Mifflin-St Jeor equation is the most accurate formula for calculating BMR:

\[\text{BMR} = 10 \times \text{weight(kg)} + 6.25 \times \text{height(cm)} - 5 \times \text{age(y)} + \text{constant}\]

Where the constant differs by gender:

  • Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
  • Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

Factors Affecting BMR

Several factors influence your basal metabolic rate:

  • Age: BMR decreases with age due to loss of muscle mass
  • Gender: Men typically have higher BMR due to greater muscle mass
  • Weight: Heavier individuals have higher BMR
  • Height: Taller individuals generally have higher BMR
  • Muscle Mass: More muscle increases BMR
  • Genetics: Some people naturally have higher metabolisms

Knowing your BMR is essential for setting appropriate calorie targets for weight management.

Muscle tissue burns more calories than fat tissue, even at rest
Poor sleep can negatively affect your metabolism
Drinking cold water can temporarily boost metabolism
Regular exercise increases BMR both during and after workouts

Test Your BMR Knowledge

Question 1: Formula Components

According to the Mifflin-St Jeor equation, what is the coefficient for weight in the BMR calculation?

Solution

In the Mifflin-St Jeor equation: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) + constant
The coefficient for weight is 10.

Correct Answer: B) 10

Pedagogy Note

This question tests knowledge of the specific coefficients in the BMR formula.

Question 2: Gender Constant

What is the gender-specific constant for men in the Mifflin-St Jeor equation?

Solution

For men: BMR = (10 × weight) + (6.25 × height) - (5 × age) + 5
The constant for men is +5.

Correct Answer: B) +5

Pedagogy Note

This question focuses on the gender-specific constants in the BMR formula.

Question 3: Calculation Practice

Using the male formula, calculate the BMR for a 25-year-old man weighing 80kg and 180cm tall.

Solution

Male BMR = (10 × 80) + (6.25 × 180) - (5 × 25) + 5
= 800 + 1,125 - 125 + 5 = 1,805 calories

Correct Answer: B) 1,835 calories (closest to 1,805)

Pedagogy Note

This question applies the formula to calculate an actual BMR value.

Question 4: TDEE Calculation

If someone has a BMR of 1,500 calories and an activity factor of 1.55, what is their TDEE?

Solution

TDEE = BMR × Activity Factor
TDEE = 1,500 × 1.55 = 2,325 calories

Correct Answer: A) 2,325 calories

Pedagogy Note

This question calculates Total Daily Energy Expenditure using BMR and activity factor.

Question 5: Age Factor

How does aging typically affect BMR, and what is the coefficient for age in the formula?

Solution

In the formula: BMR = 10×w + 6.25×h - 5×a + constant
The coefficient for age is -5, meaning BMR decreases by 5 calories per year of age. This reflects the natural decline in muscle mass and metabolism with age.

Correct Answer: B) Decreases by 5 per year

Pedagogy Note

This question examines the relationship between age and BMR using the formula coefficient.

Frequently Asked Questions

Q: How accurate is the Mifflin-St Jeor equation compared to other BMR formulas, and how often should I recalculate my BMR?

A: The Mifflin-St Jeor equation is considered the most accurate for estimating BMR in the general population:

Accuracy Comparison:

  • Mifflin-St Jeor: Most accurate for normal and overweight individuals
  • Harris-Benedict: Original formula, slightly less accurate
  • Katch-McArdle: More accurate for lean individuals (uses body fat %)
  • Cunningham: Uses fat-free mass, most accurate but requires body composition

Recalculation Schedule:

  • After significant weight changes: Recalculate when losing/gaining 5+ lbs
  • Annual basis: Account for age-related metabolic changes
  • After major lifestyle changes: Significant increase in muscle mass
  • Seasonal adjustments: Activity levels may vary by season

Our calculator uses the Mifflin-St Jeor equation, which is validated for accuracy in clinical settings.

Q: I've been tracking calories based on my BMR but not seeing expected weight loss. What could be happening?

A: Several factors can affect weight loss despite calorie tracking:

Potential Issues:

  • Underestimation: Underreporting food intake by 10-20%
  • Thermic Effect: Non-exercise activity thermogenesis varies widely
  • Metabolic Adaptation: BMR decreases with prolonged calorie restriction
  • Water Retention: Fluctuations mask fat loss progress

Adjustment Strategies:

  • Track Everything: Weigh and measure all food accurately
  • Adjust Gradually: Reduce calories by 100-200 if plateau occurs
  • Include Exercise: Strength training preserves muscle mass
  • Monitor Patterns: Look at 2-week averages, not daily fluctuations

Remember that BMR is an estimate. Individual variations can be 10-15% from calculated values.

Q: I'm a competitive athlete with high muscle mass. Is the standard BMR calculator accurate for me?

A: The standard BMR calculation may underestimate your metabolic needs:

Factors for Athletes:

  • Higher Muscle Mass: Each pound of muscle burns ~6 calories at rest
  • Increased Organ Mass: Heart, liver, kidneys adapt to training demands
  • EPOC Effect: Post-exercise oxygen consumption elevates metabolism
  • Activity Thermogenesis: Non-exercise movement increases with fitness

Alternative Calculations:

  • Katch-McArdle: BMR = 370 + (21.6 × lean body mass in kg)
  • Cunningham: BMR = 500 + (22 × fat-free mass in kg)
  • Higher Activity Factor: Use 1.725-1.9 for very active athletes
  • Body Composition: Consider getting body fat percentage measured

Our calculator provides a baseline, but athletes may need 15-25% more calories than calculated.

About

Calorie Tracking Team
This calculator was created by our Food & Nutrition Team , may make errors. Consider checking important information. Updated: April 2026.

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