What this exercise calorie calculator does
This calculator estimates calories burned during exercise using the MET (Metabolic Equivalent of Task) formula - the gold standard used by exercise physiologists and the 2011 Compendium of Physical Activities. Enter your body weight and how long you exercised; the calculator multiplies the activity's MET value by your weight (kg) and time (hours) to estimate kcal burned. Higher intensity = higher MET = more calories burned per minute.
Intensity guide for accurate results
Pick the intensity that matches what you actually did - not what you wished you did. Each exercise intensity has a specific MET value from peer-reviewed research. If you alternated paces (e.g., interval training), pick the average. For more precise tracking, use a heart rate monitor and the Heart Rate Calorie Calculator on HisabWeb - it accounts for individual cardiovascular response, which the MET method approximates.
What is MET (Metabolic Equivalent)?
MET = the energy cost of an activity relative to sitting quietly. 1 MET ≈ 3.5 mL O2 per kg of body weight per minute, or approximately 1 kcal per kg per hour at rest. Sitting = 1 MET; walking slowly = ~2.5 MET; running fast = ~13 MET. The Compendium of Physical Activities (Ainsworth et al., 2011) catalogs 821 activities with their MET values from oxygen-consumption studies. Multiplying MET × weight × time gives a robust calorie estimate for adults.
Why body weight matters
Heavier bodies burn more calories doing the same activity - more mass to move means more energy. A 90 kg person burns ~29% more calories than a 70 kg person doing the same workout. The MET formula scales linearly with weight, so accurate weight input is critical. Tip: use your current weight, not your goal weight, for the most realistic estimate.
Accuracy & limitations
MET estimates typically come within ±15-20% of metabolic-cart-measured values for moderate-intensity activities. Sources of variability: individual VO2max, body composition (more muscle = higher BMR), exercise efficiency (trained athletes burn fewer calories at the same speed), terrain, equipment, and even temperature. For more precision, use a heart-rate-based estimate (Keytel formula) or a metabolic cart in a lab.
Frequently asked questions
MET-based estimates typically come within ±15-20% of lab-measured values for moderate-intensity activities. Sources of error include individual VO2max, body composition (more muscle = higher BMR), exercise efficiency (trained athletes burn fewer calories at the same speed), and terrain. For more precision, use a heart-rate-based calculator with a chest-strap monitor.
MET (Metabolic Equivalent of Task) is the energy cost of an activity relative to sitting quietly. 1 MET ≈ 1 kcal per kg of body weight per hour. Walking briskly = ~4.3 MET; running at 6 mph = ~9.8 MET. The 2011 Compendium of Physical Activities catalogs 821 activities with their MET values - the calculator uses these standardized numbers.
MET tables include weight training (moderate ~5 MET, vigorous ~6 MET) but the estimates are less accurate than for cardio. Strength training's calorie burn is harder to estimate because rest periods, set/rep schemes, and exercise selection vary widely. For more accuracy, log your sets/reps and use a coach's deload-cycle estimation, or wear an HR monitor.
Sources
- 2011 Compendium of Physical Activities: A Second Update of Codes and MET Values— Ainsworth et al., Medicine & Science in Sports & Exercise, 2011;43(8):1575-1581
- Physical Activity Guidelines for Americans (2nd edition)— US Department of Health and Human Services
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