Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain vital functions - breathing, circulation, cell production, and temperature regulation. It represents the minimum energy needed to keep you alive and accounts for 60-75% of total daily calorie expenditure.

What is the difference between BMR and TDEE?

BMR is calories burned at complete rest. TDEE (Total Daily Energy Expenditure) is your actual daily calorie need, calculated by multiplying BMR by an activity factor. TDEE is the number you should use for nutrition planning - eating at TDEE maintains weight, below it loses weight, above it gains weight.

Which BMR formula is most accurate?

The Mifflin-St Jeor equation (used here) is considered the most accurate for most adults, with studies showing it predicts BMR within 10% for 82% of people. The Harris-Benedict equation (1919, revised 1984) is also widely used but slightly less accurate. For highly muscular or obese individuals, the Katch-McArdle formula (which uses lean body mass) may be more accurate.

How many calories should I eat to lose weight?

A deficit of 500 calories per day below TDEE typically results in approximately 0.5 kg (1 lb) of weight loss per week. This is generally considered a safe and sustainable rate. Avoid going below 1200 kcal/day for women or 1500 kcal/day for men without medical supervision.

Does BMR change over time?

Yes. BMR decreases with age (roughly 2% per decade after age 20) due to loss of muscle mass. It also decreases during prolonged caloric restriction as the body adapts. Regular resistance training helps preserve muscle mass and maintain a higher BMR. Hormonal conditions like hypothyroidism can also significantly affect BMR.

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BMR Calculator

Calculate your Basal Metabolic Rate (BMR) and daily calorie needs based on activity level using the Mifflin-St Jeor equation.

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Enter Values

Age(years)*

Biological Sex

Weight(kg)*

Height(cm)*

Activity Level

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Results

Enter values above to see results

BMR (male) = 10W + 6.25H − 5A + 5 | BMR (female) = 10W + 6.25H − 5A − 161

Variables

WWeight in kilograms

HHeight in centimeters

AAge in years

TDEETotal Daily Energy Expenditure = BMR × Activity Factor

Explanation

The Mifflin-St Jeor equation (1990) is considered the most accurate BMR formula for most people. BMR is the number of calories your body needs at complete rest to maintain basic physiological functions. TDEE multiplies BMR by an activity factor to estimate actual daily calorie needs.

What is the BMR Calculator?

Understanding your Basal Metabolic Rate is the foundation of effective nutrition and weight management. BMR tells you how many calories your body burns just to stay alive, and combined with your activity level, it determines your total daily calorie needs. This knowledge empowers you to make informed decisions about diet and exercise to achieve your health goals.

How to Use This Calculator

Enter your age, biological sex, weight, height, and activity level. The calculator uses the Mifflin-St Jeor equation - the gold standard for BMR estimation - to compute your BMR and TDEE, along with calorie targets for weight loss and weight gain.

Worked Examples

30-year-old man, 70 kg, 175 cm, lightly-to-moderately active

Using the Mifflin-St Jeor equation with an activity factor of 1.55.

BMR = 10(70) + 6.25(175) − 5(30) + 5: 1,649 kcal/day
TDEE = 1,649 × 1.55: 2,556 kcal/day
Weight-loss target (−500): ≈ 2,056 kcal/day

Burns about 1,649 kcal at rest, needs ~2,556 to maintain weight.

BMR is 60–75% of total burn — activity and food digestion make up the rest.

30-year-old woman, 60 kg, 165 cm, lightly active

Same equation, female constant (−161), activity factor 1.375.

BMR = 10(60) + 6.25(165) − 5(30) − 161: 1,320 kcal/day
TDEE = 1,320 × 1.375: 1,815 kcal/day

Maintenance is about 1,815 kcal/day.

Why Use MyCalculatorsHub's BMR Calculator?

This calculator provides a personalized calorie roadmap based on your individual characteristics and lifestyle. The activity level multipliers account for the significant impact of exercise on daily calorie needs, giving you a more accurate target than generic recommendations.

Common Mistakes to Avoid

A common mistake is overestimating activity level - most people are more sedentary than they think. Choose the activity level that honestly reflects your typical week, not your best week. Also, BMR calculations are estimates; individual metabolism varies, so adjust your calorie intake based on actual results over 2-4 weeks.