Watts to Calories Cycling Calculator

About this calculator

A power meter measures mechanical output in watts, and multiplying watts by time gives energy in joules (1 W = 1 J/s), which converts to kilocalories at 1 kcal = 4184 J. But the body isn't 100% efficient at turning food energy into pedaling power — gross metabolic efficiency for cycling is typically around 20-25%, meaning the calories actually burned are roughly 4-5 times the mechanical work done, not equal to it.

This calculator takes your average power output and ride duration, converts the mechanical work to joules, and applies a standard cycling efficiency factor to estimate calories burned. Cyclists training with a power meter use it to cross-check the calorie estimates from their head unit or Strava, and cycling coaches use it to set nutrition targets around planned training loads measured in watts rather than heart rate.