Your question can't be answered correctly without more information. It depends on your weight, plus the weight of your bike and gear, as well as your speed cycling or running. Calorie burn goes way up at higher levels of exertion. For example, you will burn substantially more calories cycling 10 miles at 18 mph than you will riding the same distance at 12 mph -- even though the slower pace takes more time. I used to think running burned more calories than cycling, but after I ran the numbers, I found that I actually burn more calories cycling for an hour than I do running the same amount of time. That's because I can cycle at a much higher pace than I can run.

I track all of my calories eaten as well as burned through exercise using an app called LoseIt. This has been real eye-opening for me because I previously hadn't realized how much more calories you burn by riding faster -- that is, using more exertion. For example, I burn about 650 calories riding to work at 14-15 mph pace but about 725 calories riding the same distance at a 16-17 mph pace.