Calculate your resting metabolic rate using Mifflin-St Jeor, Harris-Benedict, Katch-McArdle, and Cunningham formulas. Get TDEE, calorie targets, and macronutrient estimates.
Your resting metabolic rate (RMR) — the number of calories your body burns at complete rest to maintain basic life functions like breathing, circulation, and cell repair — accounts for 60–75% of your total daily energy expenditure. Understanding RMR is fundamental to effective weight management, sports nutrition, and clinical dietetics.
This calculator computes RMR using four validated formulas: Mifflin-St Jeor (recommended by the Academy of Nutrition and Dietetics as the most accurate for general use), the revised Harris-Benedict equation (1984), Katch-McArdle (using lean body mass for athletic individuals), and Cunningham (higher coefficient for competitive athletes). By comparing multiple formulas, you get a reliable range rather than relying on a single estimate.
Beyond RMR, the calculator applies standard activity multipliers to estimate your Total Daily Energy Expenditure (TDEE) and generates calorie targets for weight loss, maintenance, and lean gain goals. Macronutrient distribution (protein, fat, carbohydrates) is estimated using a balanced moderate-protein approach suitable for most healthy adults.
Whether you are trying to lose weight, gain muscle, or maintain your current physique, knowing your RMR and TDEE is essential for setting appropriate calorie targets. Without this foundation, calorie goals are guesswork — often leading to either overly restrictive diets that slow metabolism, or insufficient deficits that produce no results. This calculator provides evidence-based estimates from multiple validated formulas.
Mifflin-St Jeor: Males = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; Females = 10×weight + 6.25×height − 5×age − 161 Harris-Benedict (1984): Males = 88.362 + 13.397×weight + 4.799×height − 5.677×age; Females = 447.593 + 9.247×weight + 3.098×height − 4.330×age Katch-McArdle: 370 + 21.6 × Lean Body Mass (kg) Cunningham: 500 + 22 × Lean Body Mass (kg) TDEE = RMR × Activity Multiplier
Result: Mifflin-St Jeor: 1,780 kcal, Harris-Benedict: 1,853 kcal, TDEE: 2,817 kcal
Mifflin-St Jeor: 10×80 + 6.25×178 − 5×35 + 5 = 800 + 1112.5 − 175 + 5 = 1742.5 ≈ 1,780 kcal. Average RMR ≈ 1,817 kcal × 1.55 (moderate activity) = TDEE of ~2,817 kcal. For moderate weight loss (0.5 kg/week), target ~2,317 kcal/day.
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BMR (Basal Metabolic Rate) is measured under strict conditions (12-hour fast, 8 hours sleep, thermoneutral environment). RMR (Resting Metabolic Rate) is measured under less strict resting conditions and is typically 10–20% higher than BMR. For practical purposes, the terms are often used interchangeably.
Mifflin-St Jeor is most accurate for the general population (within ±10% of measured RMR for most people). For muscular or lean individuals, Katch-McArdle is better because it accounts for lean body mass. Harris-Benedict tends to slightly overestimate, especially in obese individuals.
Muscle tissue is metabolically active (burns ~6 kcal/kg/day), while fat tissue is relatively inert (~2 kcal/kg/day). Two people weighing 80 kg may have very different RMR if one has 15% body fat (68 kg lean mass) and another has 30% (56 kg lean mass). Katch-McArdle uses lean mass directly for this reason.
Most have minimal or no effect. Caffeine temporarily increases metabolic rate by 3–11%, and capsaicin has small effects. No supplement replaces the metabolic impact of increasing lean body mass through resistance training, which permanently raises RMR.
Yes, RMR decreases approximately 1–2% per decade after age 20, primarily due to loss of lean body mass (sarcopenia). However, resistance training can significantly attenuate this decline by maintaining muscle mass.
Activity multipliers add significant uncertainty. Most online TDEE estimates are within ±15% of actual expenditure. For better accuracy, track food intake and weight changes over 2–3 weeks, then adjust based on actual results.