BMR Calculator
Calculate your Basal Metabolic Rate to know how many calories your body burns at rest
What is BMR and why does it matter?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain vital functions like breathing and circulation. It accounts for 60-75% of your total daily calorie burn. Knowing your BMR helps you calculate accurate calorie targets for weight loss, maintenance, or muscle gain.
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Create Free AccountWhat is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform its most basic life-sustaining functions while at complete rest. These functions include breathing, blood circulation, cell production, nutrient processing, and temperature regulation. BMR typically accounts for 60-75% of your total daily calorie expenditure, making it the foundation for calculating your overall energy needs.
BMR Formulas Explained
The most commonly used BMR formulas are the Mifflin-St Jeor equation and the Harris-Benedict equation. The Mifflin-St Jeor equation (developed in 1990) is considered more accurate for modern populations: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5 (men) or -161 (women). The older Harris-Benedict equation (1918) tends to overestimate calorie needs but is still widely used in clinical settings.
Factors Affecting BMR
Several factors influence your BMR beyond age, weight, height, and sex. Muscle mass significantly increases BMR since muscle tissue burns more calories than fat tissue. Hormones (especially thyroid hormones), body temperature, climate, stress levels, and genetics also play important roles. Crash dieting can lower BMR as your body adapts to conserve energy, which is why sustainable approaches to weight management are recommended.
BMR vs TDEE: Understanding the Difference
BMR is your resting calorie burn — what your body needs just to survive. TDEE adds your daily activity on top of BMR. Think of BMR as your body's idle fuel consumption and TDEE as total fuel including driving. Never eat below your BMR; use TDEE to set your daily calorie target.
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest just to maintain basic functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) includes your BMR plus calories burned through physical activity, digestion, and daily movement. TDEE is always higher than BMR.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation is considered the most accurate BMR formula for most people, as confirmed by the American Dietetic Association. It was developed in 1990 using modern population data and tends to be more reliable than the older Harris-Benedict equation.
Can I eat below my BMR to lose weight faster?
Eating below your BMR is generally not recommended. Your BMR represents the minimum energy your body needs for basic functions. Consuming fewer calories can slow your metabolism, cause muscle loss, and lead to nutritional deficiencies. Aim to eat between your BMR and TDEE for healthy weight loss.
How can I increase my BMR?
The most effective way to increase your BMR is by building muscle mass through strength training, as muscle tissue burns more calories at rest than fat tissue. Staying hydrated, getting adequate sleep, eating enough protein, and avoiding crash diets also help maintain a healthy metabolic rate.
Does BMR change with age?
Yes, BMR typically decreases by about 1-2% per decade after age 20, primarily due to loss of muscle mass and hormonal changes. Regular strength training and maintaining muscle mass can help counteract this age-related decline in metabolic rate.