Fitbit and P90x

I doubt it, the Fitbit "calculates" calories based on what it measures as "Activity" like steps and stairs (maybe) so if you are doing works / exercise that does not have the same movements as steps or walking like cycling, it will not be as accurate. If you want to capture your P90x work I would think a heart rate monitor would be a better gauge. Now if you want to have "Activity" and Heart rate you may want to consider the Polar Loop which will be out in a week or so. The wrist band is $99 but you will also need a $65 Chest strap for the HR part so it is more expensive than the Fitbit.

Hello there, I am contemplating getting a Fitbit One...heard great things about them. My only concern is that my primary exercise program is P90x and I want to know if it makes sense to get this device given this fact. In other words, will I get a fairly accurate reading of calories burned using it.

If you are using the fitbit and doing weight training, I would love to hear from you.

I would recommend using a heart rate monitor to get a more accurate reading of calories burned. I use a polar FT7 with a chest strap for my workouts.(I think it was about $110, including chest strap, at REI.) I also use a Fitbit Flex and love it. I log my exercise calories burned from my HRM into My Fitness Pal and the calories automatically adjust. I love that the Fitbit site and MFP "communicate" with each other.