Basal Metabolic Rate Calculator

Calculate how many calories your body burns at rest

Harris-Benedict

Original formula (1919)

Mifflin-St Jeor

Modern standard (1990)

Katch-McArdle

Uses body fat percentage

Harris-Benedict Formula: The original BMR formula, developed in 1919. Good for most people but may overestimate BMR by 5-15%.

Gender

Male Female

Age

Weight

Height

Body Fat %

Activity Level

How to Use This BMR Calculator

What is BMR?

Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions while at rest. These functions include breathing, circulation, cell production, nutrient processing, and protein synthesis. BMR represents 60-70% of your total daily energy expenditure for most people.

Understanding the Formulas

Original formula (1919)

For Men: BMR = 66.5 + (13.75 × weight in kg) + (5.003 × height in cm) - (6.75 × age)

For Women: BMR = 655.1 + (9.563 × weight in kg) + (1.850 × height in cm) - (4.676 × age)

Best for: Most people seeking a general estimate. May overestimate by 5-15%.

Modern standard (1990)

For Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5

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

Best for: Most accurate general equation for the average person. Currently considered the gold standard for non-athletes.

Uses body fat percentage

BMR = 370 + (21.6 × Lean Body Mass in kg)

Where Lean Body Mass = Weight in kg × (100 - Body Fat %) / 100

Best for: Athletes and those who know their body fat percentage. Most accurate when body composition is known.

How to Calculate Your BMR

Select the calculation formula that best fits your needs.
Enter your personal details (age, gender, weight and height).
If using the Katch-McArdle formula, also enter your body fat percentage.
Choose your activity level from the dropdown menu.
Click "Calculate BMR" to see your results.

Understanding Your Results

After calculation, you'll see several results:

BMR (Basal Metabolic Rate): Calories your body needs at complete rest.
TDEE (Total Daily Energy Expenditure): Calories needed based on your activity level.
Daily Caloric Needs: Based on your goals (weight loss, maintenance, or gain).

Activity Level Guide

Activity Level	Multiplier	Description
Sedentary	1.2	Little or no exercise, desk job
Light Activity	1.375	Light exercise 1-3 days/week
Moderate Activity	1.55	Moderate exercise 3-5 days/week
Very Active	1.725	Hard exercise 6-7 days/week
Extremely Active	1.9	Physical job & hard exercise daily

Using BMR for Weight Management

For Weight Loss: Consume fewer calories than your TDEE. A safe deficit is 500-1000 calories per day, which should result in 1-2 pounds of weight loss per week.

For Maintenance: Consume approximately the same number of calories as your TDEE.

For Weight Gain: Consume more calories than your TDEE. A surplus of 500 calories per day should result in approximately 1 pound of weight gain per week.

Note: Never consume fewer calories than your BMR for extended periods as this can slow metabolism and lead to nutritional deficiencies.

Tips for Accuracy

Enter your information accurately, especially weight and height.
Be honest about your activity level to avoid overestimating or underestimating.
If you know your body fat percentage, use the Katch-McArdle formula for more accuracy.
Recalculate your BMR after significant weight changes or as you age.
Remember that BMR calculations are estimates and may vary by up to 10% from your actual metabolism.

Limitations of BMR Calculators

While BMR calculators provide valuable estimates, they have limitations:

They don't account for medical conditions that affect metabolism
Genetic factors that influence metabolism aren't considered
Accuracy decreases for individuals with very high muscle mass or obesity
The formulae are based on population averages and may not reflect individual variations