Cycling Power to Calories Calculator
Turn your average power and ride time into calories burned and total work done.
How to use the power to calories calculator
- Enter your average power in watts.
- Enter the ride duration.
- Click Calculate to see kilojoules and calories.
The most accurate calorie estimate
If you ride with a power meter, kilojoules are the gold standard for energy expenditure — far more accurate than speed- or heart-rate-based estimates.
From watts to calories
A power meter measures the mechanical work you do in kilojoules. Because the human body is roughly 20-25% efficient at turning food energy into pedal power, the kilojoules of work you produce happen to map almost one-to-one onto kilocalories burned, a convenient coincidence that makes power data excellent for fuelling.
Using the number to fuel rides
Knowing the calories and work of a ride helps you plan how much to eat during and after. Long, high-kilojoule rides demand on-bike carbohydrate to sustain pace, while the post-ride figure guides recovery nutrition so you refuel without overeating.
Frequently asked questions
How do you convert watts to calories?
Multiply average watts by ride time in seconds to get joules, then divide by 1000 for kilojoules. For cycling, kilojoules of work approximately equal calories burned.
Why do kJ and kcal match for cycling?
The human body is about 24% efficient, and the unit conversion between kJ and kcal happens to offset that, so 1 kJ of mechanical work ≈ 1 kcal expended.
Why do kilojoules roughly equal kilocalories on a bike?
Human cycling efficiency is around 20-25%, and the maths of that inefficiency means the mechanical kilojoules produced closely match the kilocalories of food energy burned.
How many calories does an average ride burn?
It depends entirely on power and duration. A two-hour endurance ride at 150 watts produces over 1,000 kJ, so well over 1,000 kcal.
Do I need to eat back all the calories from a ride?
For long rides, refuelling is important, but eating back every calorie can stall weight goals. Match intake to your training demands and overall targets.
Related tools
Calories Burned Cycling
Estimate the calories you burn on a ride from your weight, speed and time.
FTP Calculator
Estimate your Functional Threshold Power from a 20-minute test and get your full set of power training zones.
Cycling Power Calculator
Estimate the watts required to hold a given speed on a given gradient, with a breakdown of where the power goes.