Cycling Calories From Power Calculator

About this calculator

Estimating cycling calories from power output is more accurate than heart-rate or speed-based estimates because a power meter measures the actual mechanical work you produce, in watts, independent of fitness level, wind, drafting, or heart-rate drift over a long ride. The conversion accounts for the human body’s roughly 20-24% mechanical efficiency: only about a quarter of the metabolic energy you burn actually turns into forward motion, with the rest lost as heat, so calories burned ≈ (watts × time in hours × 3.6) ÷ efficiency factor.

Cyclists training with power meters — a standard tool in platforms like Strava, TrainingPeaks, and Zwift — rely on this power-to-calorie conversion because it stays consistent ride to ride even as fitness improves or heart rate drifts upward from heat or fatigue, unlike calorie estimates based on heart rate zones, which can overstate or understate effort depending on the day.

Enter your average power output and ride duration, and this calculator converts your mechanical work into an estimated calorie burn.