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Instantly calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation. Unlock science-backed calorie recommendations.
Instantly calculate your precise daily calorie needs
💡BMR uses the Mifflin-St Jeor equation — validated as the most accurate formula for modern populations by the Academy of Nutrition and Dietetics.
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This calculator is part of a comprehensive guide
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to sustain vital functions — breathing, blood circulation, cell production, and temperature regulation. The most validated formula is the Mifflin–St Jeor equation (1990): for males, BMR = 10W + 6.25H − 5A + 5; for females, BMR = 10W + 6.25H − 5A − 161, where W = weight in kg, H = height in cm, and A = age in years. BMR accounts for roughly 60–70% of total daily calorie expenditure. Multiply BMR by your activity factor (1.2–1.9) to obtain Total Daily Energy Expenditure (TDEE) — the caloric target for maintaining, losing, or gaining weight.
Expert-Reviewed by CalculatorApp.me Health Editorial Team · Updated March 2026 · 10 min read
Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain vital physiological functions at complete rest — breathing, circulation, cell production, and organ function. It represents the minimum energy your body demands to stay alive.
BMR accounts for 60–75% of your total daily energy expenditure (TDEE), making it the single most powerful contributor to your caloric needs. Understanding your BMR forms the cornerstone of any effective nutrition and weight management plan.
Age, sex, height, weight, and lean body mass directly shape your BMR. Muscle tissue is metabolically active — people with more muscle burn significantly more calories at rest.
Multiple large studies validate this formula. The Academy of Nutrition and Dietetics recommends it as the most accurate for most adults.
Roza and Shizgal revised the original 1919 equation in 1984. Practitioners worldwide have relied on it for over a century.
Uses lean body mass instead of total weight. Especially accurate for athletes and bodybuilders with significant muscle mass.
Your Total Daily Energy Expenditure (TDEE) is BMR multiplied by an activity factor representing your lifestyle. TDEE is the precise number of calories you need to maintain your current weight.
| 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 |
| Extremely Active | Very hard exercise + physical job | × 1.9 |
TDEE = BMR × Activity Multiplier. Most people drastically overestimate their activity level — when in doubt, always choose a lower category.
French chemist Antoine Lavoisier discovers that animals produce heat by oxidizing food, pioneering the foundation of metabolism science.
James Arthur Harris and Francis Gano Benedict publish the first groundbreaking BMR formula based on 239 subjects at the Carnegie Institution of Washington.
Roza and Shizgal revise the original formula based on a larger population, eliminating systematic overestimation biases that plagued the 1919 version.
M.D. Mifflin and colleagues publish their equation based on 498 subjects, which proves significantly more accurate than Harris-Benedict for contemporary populations due to changes in average body composition.
Researchers develop a lean-mass-based formula that accounts for individual differences in body composition, proving superior for athletic populations.
Large-scale studies validate Mifflin-St Jeor as the most accurate single formula for free-living adults, now the Academy of Nutrition and Dietetics' official recommendation.
Once you know your TDEE (BMR × activity level), you can set precise calorie targets for your goal and then strategically distribute those calories across macronutrients.
Powerfully preserves muscle during calorie deficit. Aim higher (1.0g) for active individuals and those over 40.
Primary energy source. Higher for endurance athletes; lower for sedentary individuals or low-carb approaches.
Essential for hormone production, fat-soluble vitamin absorption, and brain function. Never go below 0.3g/lb.
| Term | Definition | Includes Activity? | Used For |
|---|---|---|---|
| BMR | Calories burned completely at rest (awake, fasted) | No | Research baseline |
| RMR | Resting Metabolic Rate — slightly lower conditions than BMR | No | Clinical measurements |
| TDEE | Total Daily Energy Expenditure including all activity | Yes | Setting precise calorie goals |
Mifflin et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals.
Academy of Nutrition and Dietetics recommends Mifflin-St Jeor as the preferred BMR estimator.
Research on resting energy expenditure differences across metabolic phenotypes and body compositions.
BMR is the same as calories to eat
BMR is the minimum needed at complete rest. You should eat at TDEE (BMR × activity) to maintain weight, not at raw BMR.
Eating more increases your metabolism
While thermic effect of food exists (~10% of calories), overeating barely moves your BMR. Resistance training is what meaningfully raises BMR.
Low-calorie diets boost metabolism
Severe calorie restriction suppresses BMR through metabolic adaptation — known as "starvation mode." The body aggressively conserves energy at lower intakes.
BMR stays constant throughout life
BMR declines ~1–2% per decade after age 20, primarily due to loss of muscle mass. Regular strength training substantially offsets this decline.
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