How to use the calculator
If you have a power meter or smart trainer, choose Power:
- Enter the ride’s average power (not normalized or max power).
- Enter the duration in hours and minutes. Use moving time, which is what that average applies to.
- If you know your efficiency (a lab can measure it), change it under More settings. If not, leave it at 24%.
If your bike computer already shows the ride’s kilojoules (kJ), you don’t need the calculator: that number is almost exactly your calories.
If you don’t have a power meter, choose Speed or type of ride:
- Pick the type of ride. For road and casual riding you can enter your average speed on flat ground; we assign the matching Compendium activity.
- Enter your weight and the duration.
How we calculate it
From power
A power meter measures the mechanical work you do at the pedals. Turning that into the energy your body burns takes two steps:
Work (kJ) = average power (W) × time (s) ÷ 1,000
Energy burned (kcal) = work (kJ) ÷ 4.184 ÷ efficiency
Gross efficiency is the share of the energy you burn that reaches the pedals. In trained cyclists it’s around 20-25%; the rest is lost as heat. We use 24%, which makes 1 kJ of work almost exactly 1 kcal. That’s also why we show the range between 20 and 25%: at 20%, the result comes out 25% higher than at 25%.
| Average power | Calories per hour (24%) |
|---|---|
| 100 W | 359 |
| 150 W | 538 |
| 200 W | 717 |
| 250 W | 896 |
In this calculator, “calories” means kilocalories (kcal), the same unit as the Calories on US nutrition labels.
From speed or type of ride
Here we use the METs (metabolic equivalents) from the Compendium of Physical Activities, a compilation of studies that rates each activity by how many times more energy it uses than sitting at rest. One MET is roughly 1 kcal per kilogram of body weight per hour:
kcal = METs × weight (kg) × hours
The 2024 Compendium values we use (the speed bands are the Compendium’s original ones, in miles per hour):
| Activity | Code | METs | Cal/hour at 130 lb (59 kg) | at 165 lb (75 kg) | at 200 lb (91 kg) |
|---|---|---|---|---|---|
| Leisure, under 10 mph (16 km/h) | 01010 | 4.0 | 236 | 299 | 363 |
| Light, 10-11.9 mph (16-19 km/h) | 01020 | 6.8 | 401 | 509 | 617 |
| Moderate, 12-13.9 mph (19-22 km/h) | 01030 | 8.0 | 472 | 599 | 726 |
| Vigorous, 14-15.9 mph (22-26 km/h) | 01040 | 10.0 | 590 | 748 | 907 |
| Very fast, 16-19 mph (26-32 km/h) | 01050 | 12.0 | 708 | 898 | 1,089 |
| Racing, over 20 mph (32 km/h), not drafting | 01060 | 16.8 | 991 | 1,257 | 1,524 |
| Mountain biking, general | 01009 | 8.5 | 501 | 636 | 771 |
| Mountain biking, hard uphill | 01003 | 14.0 | 826 | 1,048 | 1,270 |
| E-bike, high assist | 01088 | 4.0 | 236 | 299 | 363 |
| E-bike, low assist | 01084 | 6.0 | 354 | 449 | 544 |
| Spin class or indoor cycling | 01270 | 9.0 | 531 | 674 | 816 |
Every speed and weight, already calculated, is in the cycling calories by speed chart. The result is total calories, which includes what you’d burn anyway sitting down (1 MET). We also show the extra calories, subtracting that MET, which is what the ride actually adds.
Power or METs: which to use
If you have a power meter, use power: it measures what you actually did. METs are averages from studies with very different people, bikes and conditions, and they don’t know whether you were drafting, riding with a tailwind or coasting downhill. Here’s an example with a 159 lb (72 kg) rider riding 2 hours at 15 mph (24 km/h), alone, on flat ground with no wind:
- On a road bike, hands on the hoods, that speed takes about 85 W: about 610 calories in total.
- On an upright city bike, it takes about 125 W: about 900 calories.
- With Compendium METs (10 METs for 14-15.9 mph) it would come out at 1,440 calories.
That’s a big gap, which is why you should trust kilojoules if you have a power meter. Without one, if you usually ride a road bike on flat roads, pick the category below your speed. To see the watts each speed takes, try the power to speed calculator.
Examples
- 3-hour ride at a 180 W average: 180 × 10,800 s ÷ 1,000 = 1,944 kJ. About 1,940 calories, between 1,860 and 2,320 depending on your efficiency.
- 45 minutes on the trainer at 200 W: 540 kJ, about 540 calories.
- One hour on an e-bike, 176 lb (80 kg): with high assist, 4 METs × 80 kg × 1 h = 320 calories. Without assist, 6.8 METs: 544 calories.
- Two hours of mountain biking, 154 lb (70 kg): 8.5 METs × 70 kg × 2 h = 1,190 calories.
Common mistakes
- Using total ride time. Coffee stops don’t burn like pedaling. Use moving time.
- Using normalized power. For calories, what counts is average power, which reflects total work.
- Counting your group ride speed. Drafting, you burn quite a bit less at the same speed. Pick a lower category.
- Eating back every calorie on the screen. Total calories include what your body would burn anyway. If you use the number to plan meals, look at the extra calories and at how you feel.
What the number is good for
Planning what you eat and drink on long rides, comparing rides and understanding what each pace costs. As a training guide, intensity matters more than calories: you can work out your zones with the FTP calculator or the heart rate zone calculator.
Frequently asked questions
How many calories do you burn cycling for an hour?
It mostly depends on intensity. A 159 lb (72 kg) rider burns about 290 calories cruising under 10 mph (16 km/h), about 580 at 12-13.9 mph (19-22 km/h) and about 720 at 14-15.9 mph (22-26 km/h). With a power meter: a 150 W average is about 540 calories an hour and 200 W about 720.
Why are kJ and calories almost the same on a bike?
Because your body turns only about 24% of the energy it uses into work; the rest is heat. And 1 kcal is 4.184 kJ. The two nearly cancel out: 1 kJ of work ÷ 4.184 ÷ 0.24 ≈ 1 kcal (the "calorie" on food labels).
Do you burn more calories mountain biking?
For the same time, usually yes: the Compendium gives general mountain biking 8.5 METs versus 6.8 for a 10-11.9 mph ride, and up to 14 METs for a hard climb. But what counts is intensity, not the type of bike.
How many calories do you burn on an e-bike?
According to the Compendium, 6 METs with low assist and 4 METs with high assist, versus 6.8 without assist. A 159 lb (72 kg) rider burns about 290-430 calories an hour depending on how much the motor helps.
Are calories from my watch or Strava accurate?
If they come from a power meter, they're fairly reliable. If they come only from heart rate or speed, they can be way off, because the app doesn't know whether you were drafting, riding with a tailwind or coasting downhill.