How many calories do you burn cycling? Here’s the good news: cycling is one of the best ways to burn hundreds of calories during a workout. The bad news: Most people overestimate how many calories are burned while cycling—often by a lot (like enough to overlook an extra everything bagel). But it’s not your fault.
If anything, health writers like me deserve to shoulder a large chunk of the blame. For years, we touted the amazing calorie-burning benefits of everyday activity like a leisurely coffee shop ride. We didn’t mean to delude anyone; we were being deluded ourselves, relying on tools like calorie calculators that estimate energy expenditure using formulas based on METs (short for metabolic equivalent of task) and weight. And those numbers can be highly individual—or woefully inaccurate.
For instance, let’s take that leisurely ride. Generally, cycling about 12 mph comes in at 8 METs, which means a 150-pound (68kilo) rider may burn more than 540 calories in an hour. That’s a strong “may,” though—especially if that rider is also pretty fit on the bike. Because the fitter you are, the more efficient you are, and the less energy/fewer calories you use when you ride at a given pace (file that under “life’s not fair”). That figure also never takes into account the fact that you’d be expending 1 MET and burning 68 calories that hour even if you were doing nothing more strenuous than watching TV. So if you reward your 540-calorie ride with a chocolate scone and a large latte, your weight may trend in a direction opposite of what you’re aiming for.
But everything is better now that we have electronic wearables tracking our every step and shimmy, right? Not exactly.
A Stanford study published in 2018 reported that not one of the seven devices they tested—including the Apple Watch, Fitbit Surge, Mio Alpha 2, Basis Peak, Microsoft Band, PulseOn, and the Samsung Gear S2—delivered an accurate number for calories burned. The most accurate one was off by 27 percent. The least accurate one? Off by 93 percent. Yikes. And six of the seven devices measured heart rate accurately to within 5 percent. As lead researcher Dr. Euan Ashley, professor of cardiovascular medicine, genetics and biomedical data science, told the Stanford Medical News Center, “Basing the number of doughnuts you eat on how many calories the device says you’ve burned is a really bad idea.”
GarminConnect, Strava, and other training apps might be a bit better, but they’re not perfect, either, and the number they give you depends heavily on the information you give them. The more detailed data you input about yourself, such as age, height, weight, gender, and max heart rate, the more accurately their internal algorithms can calculate your calorie burn. Wearing a heart rate monitor that is synced to your device also helps make your calorie count more accurate.
Ultimately, however, the best way to know how many calories you’re burning as you rip down the road is by using a power meter. Power meters measure the work you’re performing and display it in kilojoules, which is a unit of work that takes into account that the human body isn’t 100-percent efficient when turning energy from your fuel stores into physical work, like pedaling a bike.
“Kilojoules and calories burned in cycling convert to a 1:1 ratio,” says USA Cycling level 1 elite coach Daniel Matheny, head coach at Matheny Endurance in Colorado Springs. If your ride file says you performed 800 kJ of work, you can feel confident within a 5 percent margin of error that you burned 800 calories.
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Still, it’s extremely important to remember that even if you get the most accurate calorie data possible, there’s more to fitness and weight loss than that number. High-intensity interval workouts, for example, deliver a huge training effect by increasing your maximum oxygen consumption (VO2 max), raising your lactate threshold, and improving your economy, all of which allow you to stay “aerobic” longer, so you can burn more fat at higher intensities. But they don’t ultimately burn an impressive number of calories while you’re doing them.
Even more importantly: If it’s weight loss you’re after, you’re better off becoming more mindful of the calories you consume—looking most closely at the quality while keeping an eye on the quantity—than those calories burned. Research has clearly demonstrated that you can lose weight relatively easily without exercising, but it’s far harder to shed pounds without a healthy diet. For guidance, a recent landmark study of more than 135,000 people across five continents found that a diet that avoids excessive carbs (more than 60 percent of your daily intake) and includes about 35 percent of fat, as well as three to four servings of fruits, veggies, and legumes a day is your best bet for good health.
The bottom line: Keep riding, and include a couple of hard outings with hills or intervals every week. Feed yourself a high-quality diet rich in whole, unprocessed foods. If tracking calories motivates you, track away! But use accurate tools like a power meter and try not to obsess over it.