Calories burned issue?

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Hello guys,

Just wondering if anyone could help me out with the pickle I'm having. I have a stationary bike/elliptical trainer and it tells me how many calories I burn on the screen. For example, I'll sometimes do half an hour on the elliptical and 10 mins on the bike. For this amount of time, the machine tells me I've burned 180 calories. (I work really hard and build up a sweat) but My Fitness Pal tells me I've burnt like 500 calories when I type in that I've done the same exercise???

Quite a big difference, just want to know which is accurate! Wondering if anyone could help me out?

There's also a chance that I haven't entered my correct weight/height into the bike because it seemed to reset itself when unplugged.