calories burned on MFP vs actual calories burned

soxgirlie2476

I log all my food into MFP and it links/synch to my fit bit dashboard. Tonight I will be going to the gym and getting on the elliptical for 45 mins and it says 600+ calories burned according to MFP. I am wondering if anyone logs only into fitbit and if that calories burned are much different than MFP approximation of calories burned? I always tend to overestimate food calories that I don't know exact counts on and want to be sure I am not way overestimating my calories burned at times by believing MFP calculations.