Calories burned cycling: how many do you really burn?

You get home from a ride, your watch says 900 calories, and a little voice tells you that you have “earned” a pizza. Before you order, it helps to know where that number comes from. The energy cost of an hour on the bike can vary threefold depending on your weight, your speed, the hills and the wind, and not every estimate floating around online is equally reliable.

The scientific reference is the Compendium of Physical Activities, updated in 2024 by a team of American researchers. It gives each activity a MET value, a multiple of your resting energy use: 4 METs means you burn about four times as much energy as you would sitting on the sofa. The maths fits on one line: kcal ≈ METs × body weight (kg) × time (hours). One hour at 8 METs for a 70 kg rider therefore comes to 560 kcal.

The table below applies this formula to the main riding speeds, from 55 to 100 kg (121 to 220 lb), for 30 and 60 minutes. A heavier person burns more because they are moving more mass: at the same speed, going from 55 to 100 kg almost doubles the burn. Find your row, then keep in mind that wind, hills and traffic-light stops can push the real figure up or down.

On a city bike, pottering to the shops or cruising along a canal path, you stay under 10 mph (16 km/h): the Compendium gives this 4 METs, about 280 kcal an hour at 70 kg. Bike commuting, riding to and from work at your own pace, sits clearly higher at 6.8 METs: you have a time to keep to, you push off again at every set of lights, and there is often a hill somewhere. Twenty minutes each way therefore adds up to roughly 320 kcal a day at 70 kg, without ever feeling like a workout.

On a road bike, speed is in charge. Air resistance rises very quickly with pace: going from 12 to 17 mph (20 to 28 km/h) takes far more power, which explains the jump from 8 to 12 METs. Hills, headwinds, the weight of the bike, your position and your tyre pressure all play a part too, so two rides at an average of 15 mph will not necessarily cost the same. Riding in a group, sheltered behind other wheels, also saves a surprising amount of energy.

Mountain biking, finally, is rarely steady: sharp accelerations, soft ground, descents where you recover and climbs where you dig deep. The Compendium gives 8.5 METs to a general mountain bike ride and 14 METs to a hard uphill effort, one of the highest values in the whole category, just behind road racing at more than 20 mph (32 km/h).

It is one of the most common questions, and the answer is reassuring: an electric-assist bike does not pedal for you. The motor only amplifies the effort you put in, and it only runs while you are pedalling. The 2024 Compendium lists three cases: 6.8 METs with no assist, 6.0 METs with light assist and 4.0 METs with high assist.

In practice, at 70 kg, an hour on an e-bike in a low assist mode burns about 420 kcal, against 475 kcal for the same ride with no help, so roughly 12% less. In turbo mode you drop to 280 kcal, about 40% less. A systematic review from the University of Bristol that pooled 17 studies concluded that e-cycling provides physical activity of at least moderate intensity, lower than conventional cycling but higher than walking, and that it can improve fitness in people who were previously inactive.

The other advantage is practical: on an e-bike you are more willing to take on longer or hillier routes, you arrive at work less sweaty and you end up riding more often. An e-bike used every day will therefore burn far more calories than a regular bike gathering dust in the shed. To get the most out of it, turn the assist down on the flat and save the high setting for climbs and headwinds.

Indoors there are no descents to coast down and no red lights to stop at, so every minute counts. The Compendium gives 6.8 METs to stationary cycling “in general”, but the value climbs with power: 6.0 METs at around 90 to 100 watts, 8.0 METs between 126 and 150 watts and more than 10 METs above 150 watts. A spin class is rated at 9.0 METs, and interactive virtual cycling, the kind you do on platforms such as Zwift with a smart trainer, at 8.8 METs.

If your bike or trainer measures power, you have a far more reliable tool than a heart-rate estimate. Cyclists use a handy rule of thumb: 1 kilojoule of work on the screen ≈ 1 kcal burned. It works because the body only turns roughly a fifth to a quarter of the energy it uses into work at the pedals, and one kilocalorie equals 4.18 kilojoules: the two factors almost cancel out. An hour at 150 watts is 540 kJ, so about 540 kcal, very close to the 560 kcal the Compendium gives for a 70 kg rider.

If you are torn between several gym machines, our article on elliptical calories compares the cross-trainer with the stationary bike and the treadmill.

Per hour, cycling holds its own against running: 560 kcal at around 12 to 14 mph versus 650 kcal running at 6 mph (10 km/h), for a 70 kg person. Per mile, though, the gap is huge. The bicycle is a remarkably efficient way to get around: the wheel removes the impacts and the up-and-down movement of the body, so a kilometre on a bike costs only about 20 to 30 kcal (30 to 50 kcal per mile), against around 50 kcal per km walking and 65 kcal per km running.

That is why it makes more sense to think in time than in distance. A 30 km (19-mile) ride sounds impressive, but at 15 mph it is a little over an hour of effort, roughly the time a recreational runner needs for a 10K. Swimming is a case apart: you move slowly through the water, so the cost per kilometre is very high (around 200 kcal), while an hour of easy front crawl stays at about 400 kcal.

To compare with the other big endurance sport, our guide to calories burned running breaks down the burn by pace and body weight.

Yes, as long as you do not eat it all back. The most telling study comes from Copenhagen, where cycling is part of everyday life. Researchers split 130 inactive adults with overweight into a control group, a group that cycled to work and two groups that exercised in their free time, at either moderate or vigorous intensity. After six months, the bike commuters had lost an average of 4.2 kg of fat mass (about 9 lb), almost as much as the vigorous exercise group (4.5 kg) and more than the moderate group (2.6 kg).

The same trial highlights a well-known trap: compensation. Part of the calories you burn get “clawed back”, mostly through a bigger appetite. In the moderate group, the researchers estimated that 77% of the exercise energy expenditure was compensated for, against 38% among the cyclists. Another American study, E-MECHANIC, found that adults with overweight who were given supervised exercise ate around 90 to 125 kcal more per day than the control group, which wiped out part of the expected weight loss.

So cycling does help you lose weight, but it works best as an ally of a moderate calorie deficit, not as a licence to eat more. An hour at 12 to 14 mph is about 490 net kcal at 70 kg: that is real, but a pastry, a can of soda and a handful of biscuits afterwards can erase a good chunk of it. The sensible habit is to keep an eye on what you eat on riding days, without starving yourself after a big effort either.

Your GPS watch or bike computer shows a total down to the last calorie, which gives an impression of precision. Research suggests caution. At Stanford, researchers tested seven smartwatches on 60 volunteers who walked, ran and cycled while their real energy expenditure was measured by calorimetry. Heart rate was often accurate on the bike, but no watch estimated calories with less than 20% error: the median error ranged from 27% to 93% depending on the model.

A British meta-analysis of 60 studies reached the same conclusion: accuracy varies a lot from one activity to another, and it improves when a device combines an accelerometer with heart rate. On a bike your wrist barely moves, so the algorithm has to guess your effort mostly from your heart rate, which also rises with heat, stress, fatigue or one coffee too many.

The real risk is not the error itself but what you do with it. If your watch inflates your burn by 30% and you “eat back” those calories, your planned deficit quietly disappears and you are left wondering why the scale will not move. Treat the number as a ballpark, compare it with the tables in this article and, if you ride with a power meter, trust the kilojoules instead.

For a ride of less than an hour there is no need to load up: a normal meal in the hours before and some water are enough. Things change as the ride gets longer. Sports scientist Asker Jeukendrup suggests simple benchmarks: small amounts of carbohydrate, up to about 30 g an hour, for efforts of 1 to 2 hours; up to 60 g an hour for 2 to 3 hours; and up to 90 g an hour beyond roughly 2.5 hours, using a mix of sugars (glucose and fructose) that the gut absorbs better. He adds that these amounts should come down when the intensity is low.

In practice, that means a small bite every 20 to 30 minutes: a banana, a cereal bar, dried fruit, fruit jellies, and gels or a sports drink for those who ride hard and long. Start early, before you feel hungry, and try your food out in training rather than on the day of a sportive. Drink regularly, and more when it is hot.

After the ride, a meal that combines carbohydrates and protein helps refill your stores and repair your muscles; our article on muscle recovery covers the habits that matter. If your goal is weight loss, remember that all of this counts towards your day: on an easy 90-minute ride, a sports drink is often unnecessary.

The WHO recommends that adults get at least 150 minutes of moderate activity a week: three 50-minute rides, or five 30-minute commutes there and back, are enough to hit it. Here is a four-week progression that works whether you ride outdoors or on a stationary bike.

The calories you burn cycling depend above all on your weight and your speed: for a 70 kg person, count on about 280 kcal an hour on a leisurely ride, 560 kcal at around 12 to 14 mph and 840 kcal at 16 to 19 mph. An e-bike burns 12 to 40% less depending on the assist level, but it often makes you ride more often and further. Per mile, cycling is very economical, so think in minutes of effort rather than in distance. It genuinely helps you lose body fat, as the Copenhagen bike-commuting study showed, provided you do not compensate at the table. Treat your watch’s figures as a ballpark, fuel your long rides and, if you have a health condition or are returning to exercise after a long break, ask your doctor for advice first.