Calorie Burn Calculator — Cycling Calories from Power

With a power meter, this is the most accurate way to estimate cycling calories. The default 24% efficiency follows the industry convention used by TrainingPeaks, TrainerRoad and CTS, where the kilojoules of mechanical work roughly equal the kilocalories burned. Note that laboratory-measured GROSS efficiency for most trained cyclists is nearer 20–23% (Moseley & Jeukendrup found ~19.8%), so your true calorie burn may be a few percent higher than shown — lower the efficiency field toward 0.21 for a more conservative (higher-calorie) estimate.

Heart rate is affected by temperature, caffeine, stress and fatigue. Power directly measures mechanical work output, making it far more reliable for calorie estimation.

Gross efficiency is the share of total metabolic energy you turn into mechanical work at the pedals. For trained cyclists this is typically about 20–24% (the 24% default is an upper-range convention; 25.8% you may see quoted is DELTA efficiency, a different metric). The remaining energy is lost as heat, so total calories burned is roughly 4 to 5 times the mechanical energy you produce.

If two riders produce the same power for the same duration, they burn approximately the same calories. However, heavier riders typically need more power to maintain the same speed.