Watts to Calories Calculator

Watts to Calories Calculator

Power meters report watts and kilojoules, but most people think in calories. Enter your average power and how long you rode, and this calculator returns the mechanical work in kilojoules and the calories you burned, using a typical cycling efficiency of about 24%. Use it to check a ride against your nutrition, compare efforts, or understand why kilojoules of work and calories burned end up roughly equal on a bike.

Mechanical work is power × time: watts × seconds gives joules, shown here in kilojoules. Cyclists burn more energy than that work because muscles are only about 24% efficient — the rest becomes heat. Dividing the work by 0.24 and converting to kilocalories is why a useful rule of thumb is that calories burned ≈ kilojoules of work. This counts exercise energy only, not your resting metabolism, and assumes typical cycling efficiency.