Calories Burned Calculator

The Metabolic Equivalent of Task (MET) is a standardized way of expressing the energy cost of physical activities relative to rest. A MET value of 1 corresponds to the energy expended while sitting quietly — approximately 1 kcal per kilogram of body weight per hour. An activity with a MET of 7 therefore burns seven times as many calories as sitting still. The Compendium of Physical Activities, maintained by researchers at Arizona State University, catalogues MET values for over 800 distinct activities, from sleeping (0.95 MET) to competitive running at high speed (up to 23 MET).

The core formula is: Calories Burned = MET × Weight (kg) × Time (hours). This expression derives from the oxygen consumption definition of MET — 1 MET corresponds to roughly 3.5 mL O₂ per kg per minute, and burning 1 litre of oxygen releases approximately 5 kcal. Multiplying through and simplifying yields the compact formula used here. Body weight is a direct multiplier because heavier individuals must move more mass against gravity and friction, consuming proportionally more energy. Duration in hours converts the per-hour rate into total energy expended.

Practical applications span fitness, clinical exercise physiology, and public health. Personal trainers use MET-based estimates to set realistic calorie targets for clients on fat-loss programmes. Registered dietitians cross-reference exercise expenditure with dietary intake to calculate daily energy balance. Researchers use MET-weighted activity logs in epidemiological studies to quantify population-level physical activity. Wearable fitness trackers and gym machines use the same underlying formula, though they may add heart-rate adjustments for improved accuracy at non-standard intensities.

The MET formula provides a population-average estimate and carries several important caveats. First, individual metabolic rates vary by up to 20–30% from the population mean due to differences in fitness level, body composition, age, hormonal status, and genetics — two people of identical weight may burn significantly different calories doing the same activity. Second, the formula does not account for the post-exercise oxygen consumption (EPOC) effect, whereby high-intensity exercise elevates metabolism for minutes to hours after activity ceases, leading to underestimation of total energy cost. Third, MET values from the Compendium are measured under standardised lab conditions; real-world terrain, wind resistance, incline, and carrying equipment can raise or lower actual expenditure substantially. Fourth, the formula assumes a steady, continuous effort — interval training with alternating high and low intensities is less accurately represented by a single MET value. Fifth, the formula is less accurate for very low-intensity activities where individual resting metabolic rate variation dominates, and for aquatic exercises where body weight is partially supported. For clinical or precision nutrition purposes, indirect calorimetry remains the gold standard.