Accuracy of MFP burn?

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Just throwing this out there...

I take an Aikido class twice a week and this past Saturday I took a seminar. I decided not to log the day because I knew there would be a potluck after the seminar and wanted to count it as my cheat day for the week. Well, for giggles I logged it anyway and counted the minutes of martial arts I performed during the day...

My fitness pal said I burned close to 7k of calories. It usually tells me I burn about 800 for 60 minutes, and I don't really put a lot of faith in it.

How accurate is this? I have no experience with martial arts before now, but I know a half hour on the treadmill feels like more work and burns nowhere near a half hour of martial arts according to the app.