How many calories do you burn by swimming?

There no way to make a reasonable comparison. The energy burned depends on the physical activity involved and the duration of the involvement. You can swim fast and run slow or run fast and swim slow and get different results for each and everything between. The only reasonable way to try to compare the two is by distance. And, in that case, swimming burns more calories because it is a much less efficient way to move your bodyweight. It is similar or analogous to the difference between running and riding a bike. The bicycle makes the perambulation more efficient so you go the same distance with less energy. They're both excellent forms of aerobic exercise so I will make it official. You both win! Good luck and good health!!

i don't know for sure but you do burn a lot of claories. Swimming is a good way of burning calories since your body tempt to do more work in a more heavy environment.