Watts to Calories Calculator
Cycling power to work and calories
AI logs your meals from a photo. Diet & workouts in one app.Get the free appyour average power for the ride, e.g. 200
ride length in minutes, e.g. 60
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.
Frequently Asked Questions
- What does the watts-to-calories calculator do?
- It converts your cycling power output into energy. Enter your average power in watts and duration, and it returns the mechanical work done in kilojoules along with the calories you burned, helping you match training effort to nutrition.
- How do watts convert to calories burned?
- Average watts times duration in seconds gives work in joules, divided by 1,000 for kilojoules. Conveniently, kilojoules of work roughly equal the calories burned, because human cycling efficiency of about 20–25% nearly cancels the kJ-to-kcal conversion factor.
- Why do kilojoules roughly equal calories on a bike?
- Cyclists are only about 20–25% efficient, so for every kilojoule of mechanical work you actually expend about four to five kilojoules of energy. Since one calorie is about 4.18 kilojoules, the two numbers end up nearly equal, making kJ a handy calorie estimate.