BMR Calculator

Calculate your Basal Metabolic Rate (BMR) to understand how many calories your body needs at complete rest.

What is BMR?

Basal Metabolic Rate (BMR) represents the minimum amount of energy (calories) your body needs to perform its basic functions while at complete rest. These functions include breathing, circulation, cell production, nutrient processing, and maintaining body temperature.

Your BMR accounts for approximately 60-70% of the total calories you burn each day, making it the largest component of your total daily energy expenditure (TDEE).

BMR Formulas

There are several formulas used to calculate BMR. The two most common are:

Mifflin-St Jeor Formula (Recommended)

This is considered the most accurate formula for most people:

For men:

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

For women:

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

Harris-Benedict Formula (Original)

This is an older formula that is still widely used:

For men:

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

For women:

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

Factors Affecting BMR

Several factors can influence your BMR:

Age: BMR typically decreases with age due to loss of muscle mass and hormonal changes.
Body Composition: Muscle tissue burns more calories than fat tissue, even at rest. People with more muscle mass have a higher BMR.
Gender: Men generally have a higher BMR than women due to greater muscle mass and less body fat.
Genetics: Some people naturally have a faster or slower metabolism due to genetic factors.
Hormones: Thyroid hormones, growth hormone, and testosterone can all affect BMR.
Physical Activity: Regular exercise can increase BMR by building muscle mass.
Environmental Temperature: Extreme cold or heat can temporarily increase BMR as your body works to maintain its core temperature.

How to Use Your BMR

Your BMR is the foundation for understanding your caloric needs:

To maintain weight, you need to consume calories equal to your TDEE (BMR × activity factor).
To lose weight, you need to create a calorie deficit by consuming fewer calories than your TDEE.
To gain weight, you need to consume more calories than your TDEE.
For weight loss, a moderate deficit of 500-1000 calories per day is generally recommended for safe, sustainable results (1-2 pounds per week).
Never consume fewer calories than your BMR for extended periods, as this can slow your metabolism and lead to nutritional deficiencies.

Limitations of BMR Calculations

While BMR calculations provide a useful estimate, they have limitations:

They are estimates and may not account for individual variations in metabolism.
They don't account for specific medical conditions that may affect metabolism.
They may be less accurate for very athletic individuals, the elderly, or those who are significantly overweight.
For the most accurate measurement of BMR, clinical tests like indirect calorimetry would be needed.