BMR Calculator
Calculate the calories your body burns at complete rest — the baseline for any nutrition or fat-loss plan.
What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs to sustain basic physiological functions — breathing, circulation, cell production, and temperature regulation — while at complete rest. It represents the minimum energy your body requires to stay alive for 24 hours.
BMR accounts for roughly 60–70% of total daily calorie expenditure for most people. The remaining calories come from digestion (the thermic effect of food, ~10%) and physical activity (~20–30%).
This calculator uses the Mifflin-St Jeor equation, published in 1990 and considered the most accurate prediction formula for most adults. It requires four inputs: height, weight, age, and sex.
The Mifflin-St Jeor Formula
| Sex | Formula |
|---|---|
| Male | BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5 |
| Female | BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161 |
The equation was validated against measured resting metabolic rate (RMR) via indirect calorimetry and was found to be more accurate than the older Harris-Benedict equation, especially for overweight and obese individuals.
Worked Examples
Example 1: 35-year-old male, 180 cm, 80 kg.
BMR = (10 × 80) + (6.25 × 180) − (5 × 35) + 5 = 800 + 1125 − 175 + 5 = 1,755 kcal/day
Example 2: 28-year-old female, 165 cm, 62 kg.
BMR = (10 × 62) + (6.25 × 165) − (5 × 28) − 161 = 620 + 1031.25 − 140 − 161 = 1,350 kcal/day
Example 3: 50-year-old male, 175 cm, 95 kg.
BMR = (10 × 95) + (6.25 × 175) − (5 × 50) + 5 = 950 + 1093.75 − 250 + 5 = 1,799 kcal/day
Frequently Asked Questions
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BMR is the calories you burn at complete rest. TDEE (Total Daily Energy Expenditure) is your actual daily calorie burn, factoring in physical activity. TDEE = BMR × an activity multiplier. For most people, TDEE is 1.2–1.9× their BMR.
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Eating below your BMR for extended periods is generally not recommended unless under medical supervision. It can cause muscle loss, metabolic adaptation, and nutrient deficiencies. Most dietitians recommend a minimum intake of 1,200 kcal for women and 1,500 kcal for men.
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Yes. Muscle tissue burns more calories at rest than fat tissue. People with higher muscle mass have a higher BMR. This is one reason resistance training is effective for long-term weight management — it raises your resting calorie burn.
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Yes. BMR typically decreases by around 1–2% per decade after age 20, primarily because muscle mass tends to decline with age. Regular strength training can slow this decline significantly.
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For most adults, yes. Studies consistently show it predicts RMR within 10% for the majority of people. The Katch-McArdle formula can be more accurate if you know your lean body mass, as it accounts for body composition rather than total body weight.
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On average, males have greater muscle mass and less body fat than females of equivalent weight and height. Muscle tissue is metabolically more active than fat tissue, resulting in a higher resting calorie burn. Hormonal differences (testosterone promotes muscle protein synthesis) also play a role.