BMR Calculator

Your BMR Results

0 Calories/Day

Calculated using the Mifflin-St Jeor formula.

What This Means

Your body uses about 0 calories a day just to stay alive — even if you stayed in bed all day. That energy goes into things like breathing, pumping blood, and keeping your cells running.

Total Daily Energy Expenditure (TDEE)

To estimate your total daily calorie needs based on activity level, use the table below:

Activity Level	Description	Calories/Day

What is BMR?

Your Basal Metabolic Rate (BMR) represents the minimum number of calories your body requires to perform essential life-sustaining functions while at complete rest. Think of it as the energy needed to keep your body functioning if you were to lie in bed all day without moving.

Did you know? For most people, BMR constitutes about 60-75% of total daily energy expenditure. This makes it the largest component of your metabolism.

Factors That Influence Your BMR

Several key factors determine your individual metabolic rate:

Lean body mass: Muscle tissue is more metabolically active than fat tissue, so those with higher muscle mass typically have higher BMRs
Age: Metabolism generally slows with age due to decreased muscle mass and hormonal changes
Biological sex: Men typically have higher BMRs than women due to generally greater muscle mass
Body size: Larger bodies have higher BMRs as they have more cells requiring energy
Genetics: Some people naturally have faster or slower metabolisms
Hormonal factors: Thyroid function and other hormonal balances significantly impact metabolic rate

Mifflin-St Jeor vs. Harris-Benedict Formulas

Mifflin-St Jeor Formula

Developed in 1990, the Mifflin-St Jeor equation is currently considered the most accurate BMR formula for healthy individuals. It tends to be within 10% of real metabolic rate measurements for most people.

Equation for men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5

Equation for women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

Harris-Benedict Formula

Originally developed in 1919 and revised in 1984, the Harris-Benedict equation was the standard for many decades. While still widely used, research suggests it may overestimate BMR by approximately 5% on average.

Equation for men: 66.47 + (13.75 × weight in kg) + (5.003 × height in cm) - (6.755 × age in years)

Equation for women: 655.1 + (9.563 × weight in kg) + (1.850 × height in cm) - (4.676 × age in years)

Practical Applications of Knowing Your BMR

Understanding your Basal Metabolic Rate provides a scientific foundation for:

Weight management: Create precise calorie deficits for weight loss or surpluses for muscle gain
Nutrition planning: Develop meal plans that match your energy needs
Fitness programming: Adjust nutrition around workout schedules
Metabolic health monitoring: Track changes in metabolism over time

Frequently Asked Questions

Can I change my BMR?

Yes, you can influence your BMR through various strategies. Building lean muscle mass through resistance training is one of the most effective ways to increase your metabolic rate. Other factors include proper nutrition, adequate sleep, and managing stress levels.

How often should I recalculate my BMR?

You should recalculate your BMR whenever your body weight changes significantly (5% or more). Additionally, as you age, your metabolic rate naturally changes, so recalculating annually can help maintain accuracy.

Why does my BMR change depending on the formula?

Good question. Each formula was created from different research studies. The Mifflin-St Jeor equation usually lines up better with today’s lifestyles, while Harris-Benedict can come out a little high for some people.

How does BMR relate to TDEE?

While BMR represents calories burned at complete rest, Total Daily Energy Expenditure (TDEE) includes all activities. TDEE is calculated by multiplying your BMR by an activity factor that accounts for your daily movement and exercise.