Cycling Calories From Power Calculator

How it is calculated

The tool first converts your average power and ride time into mechanical work: work (kJ) = power (W) × duration (min) × 60 ÷ 1000. It then reports calories as equal to that work in kilojoules: kcal ≈ kJ. This one-to-one shortcut works because the body turns only about a quarter of the food energy it burns into pedalling work, and one kcal is about 4.2 kJ, so the two effects almost cancel out. The tool shows no separate efficiency setting. The third result is calories per minute, kcal ÷ minutes. Power and duration must both be above zero. Use average power for the whole ride, including easy parts, not your best effort.

Common mistakes

• Entering the duration in hours. The box takes minutes, so a 1.5 hour ride must be typed as 90, otherwise the result is 60 times too low.
• Using peak or normalised power in place of average power. Normalised power is higher than what you really did, so the calorie figure comes out too high.
• Leaving out the stops. Time spent coasting or standing still at lights counts as zero watts in an honest average, so include it in the power or use the moving time for both.
• Expecting the count to include your resting metabolism. The figure is only the energy cost of pedalling, not what you would burn anyway during that time.
• Treating the number as exact. The kcal equals kJ shortcut assumes a typical efficiency, so individual riders can differ by several percent.