What is BMR (Basal Metabolic Rate)?

Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain essential life functions — breathing, blood circulation, cell production, body temperature regulation, and organ function. It represents the minimum caloric intake your body needs just to survive if you stayed in bed all day. BMR accounts for approximately 60-70% of total daily calorie expenditure.

How is BMR calculated?

BMR is calculated using validated scientific formulas. The Mifflin-St Jeor Equation (most accurate for most people) is: 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. Our calculator applies this formula automatically based on your input.

What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the calories you burn at complete rest. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor to account for your daily movement and exercise. TDEE is the actual number of calories you need to eat to maintain your current weight. Our calculator shows both values.

How do I use my BMR to lose weight?

To lose weight, you need to consume fewer calories than your TDEE (a caloric deficit). A safe deficit is 300-500 calories per day, which results in approximately 0.3-0.5 kg (0.5-1 lb) of weight loss per week. Eating below your BMR is generally not recommended as it can impair metabolism and cause muscle loss.

Which BMR formula is most accurate?

The Mifflin-St Jeor Equation (1990) is considered the most accurate for most people. The older Harris-Benedict Equation (1919, revised 1984) tends to overestimate slightly. For very muscular or obese individuals, the Katch-McArdle formula (which uses lean body mass) may be more accurate. Our calculator uses Mifflin-St Jeor by default.

Does BMR change with age?

Yes. BMR decreases with age because muscle mass naturally declines (sarcopenia) and metabolic processes slow down. After age 20, BMR decreases by approximately 1-2% per decade. This is why older adults often need fewer calories to maintain weight than younger adults of the same height and weight.

BMR Calculator

Free online BMR Calculator. Simple, fast, and secure tool running in your browser.

Free BMR Calculator — Calculate Your Basal Metabolic Rate

Our BMR Calculator uses the scientifically validated Mifflin-St Jeor Equation to calculate your Basal Metabolic Rate — the number of calories your body burns per day at complete rest. Understanding your BMR is the foundation of any successful nutrition plan, whether your goal is weight loss, muscle gain, or maintaining your current weight.

Enter your age, gender, height, and weight to get your BMR instantly. The calculator also shows your TDEE (Total Daily Energy Expenditure) based on your selected activity level — the actual calories you need to maintain, lose, or gain weight.

BMR Formulas Used

Mifflin-St Jeor Equation (Default — Most Accurate)

For Men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5

For Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161

Harris-Benedict Equation (Revised)

For Men: BMR = 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age)

For Women: BMR = 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age)

TDEE Activity Multipliers

Activity Level	Description	Multiplier
Sedentary	Little or no exercise, desk job	× 1.2
Lightly Active	Light exercise 1-3 days/week	× 1.375
Moderately Active	Moderate exercise 3-5 days/week	× 1.55
Very Active	Hard exercise 6-7 days/week	× 1.725
Extra Active	Very hard exercise + physical job	× 1.9

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