How do you calculate exercise calories?

drshona

I'm planning to use swimming and running as my main exercise but the weather is horrendous today and it's a running day, so I'm going to try to make myself use the crosstrainer and rowing machine that I have for this reason. Can I believe the calorie count on them? I've never paid it much attention before. Or would I be better entering '30 minutes rowing machine' or something into MPF?

Speaking of which, for yesterday's swim, I just entered '30 minutes breaststroke' into MFP and assumed the calories it assigned were vaguely accurate. And for running I use Endomondo and, likewise, assume the calories it assigns are correct.

Are these methods accurate? At least vaguely.