Cycling Calorie Burn by Power Calculator

About this calculator

A power meter measures mechanical work output directly in watts, which converts to calories far more accurately than heart rate or speed because it isn’t affected by drafting, wind, terrain or cardiac drift over a long ride. The conversion uses your average power multiplied by ride duration to get kilojoules of mechanical work, then divides by gross efficiency (typically around 20-25% for trained cyclists) to estimate the metabolic calories actually burned, since the body wastes most of the energy it converts as heat.

Cyclists training with a power meter use this calculation to set nutrition targets for long rides — knowing calories burned, split into the carbohydrate and fat contribution at a given intensity, tells you how many carbs per hour you need to eat to avoid bonking, since higher-intensity efforts shift fuel use toward carbohydrate and away from fat. It’s more reliable for fueling decisions than calorie estimates from a bike computer’s default formulas, which are usually just rough speed- or heart-rate-based guesses.

This calculator takes your average power and ride duration and returns total calories burned, the carbohydrate/fat split, and a recommended carbs-per-hour fuelling target.