Cycling Calories Calculator

Power-based, by a wide margin, if you actually have a calibrated power meter. The MET formula treats every rider at a given intensity as burning the same multiple of resting metabolism. Real burn varies with fitness, body composition, drag, wind, and gearing. Lab studies (Byrne et al., Medicine and Science in Sports and Exercise, 2005) put Compendium MET values within 10 to 20 percent of measured oxygen cost. A power meter measures mechanical work directly and, once paired with a gross efficiency value (0.22 to 0.24 for trained cyclists), lands within 5 to 8 percent of indirect calorimetry. If you have a Stages, Quarq, Garmin Rally, or smart trainer reading watts, use power-based mode. If not, the MET tier is a fine planning estimate.

Because you are doing extra work against gravity. The energy cost of holding 8 mph on a flat road is dominated by air drag and rolling resistance, both small at that speed. The energy cost of holding 8 mph up a 6 percent grade adds a gravity term equal to weight x grade x distance, which for an 80 kg rider plus bike (90 kg total) over one mile is roughly 90 kg x 0.06 x 1609 m x 9.81 = 85,000 joules, or about 20 kcal of mechanical work. At 23 percent gross efficiency that is 87 kcal of metabolic burn for the climb alone, on top of whatever you would have burned on flat ground. The 2011 Compendium MET tiers are calibrated to typical mixed terrain, so steep sustained climbs at the same speed run 30 to 60 percent higher than the table suggests.

They can be similar when measured mechanical power and session time match, but the calculator's activity labels are not equivalent workloads. The 2011 Compendium assigns 6.8 MET to stationary cycling at 90 to 100 W and 8.8 MET at 101 to 160 W. Outdoor speed also changes with wind, grade, drafting, and coasting. Use measured average watts when available. Otherwise, choose the activity and effort description that best matches the session.

Gross efficiency is the fraction of metabolic energy you turn into mechanical work at the pedals. The rest leaves the body as heat. Sustained cycling efficiency for trained adults sits in a tight band: Coyle's lab work at the University of Texas in the 1990s measured 0.18 to 0.23 across elite Tour de France riders, Coggan and Allen quote 0.22 to 0.24 in Training and Racing with a Power Meter (3rd ed., 2019), and recent indirect calorimetry studies (Joyner and Coyle, 2008; Mulder et al., 2015) settle the typical trained adult around 0.22 to 0.24. Untrained or beginner cyclists are a few points lower (0.18 to 0.20) because their pedal stroke wastes more energy on non-propulsive motion. The calculator caps the input at 0.18 to 0.30 to reject typos while still admitting the full plausible range.

Sustained low-to-moderate intensity (the casual to moderate tiers in this calculator, roughly 60 to 75 percent of max heart rate) drives the largest aerobic adaptations per training hour. Two mechanisms dominate. First, mitochondrial biogenesis: low-intensity continuous work signals PGC-1 alpha activation that increases both the number and size of mitochondria in slow-twitch fibers (Holloszy 1967; Hood et al., 2019). Second, capillary density: aerobic volume increases the number of capillaries per muscle fiber, which raises oxygen delivery and carbon dioxide clearance at any given workload. Over a 12 to 16 week base phase these adaptations let you hold the same pace or wattage at a lower heart rate, which is the field signal that the base is working. Stephen Seiler's polarized training research finds elite endurance athletes spend roughly 80 percent of their time in this zone, which is a much bigger volume than most recreational cyclists log.