Wii Fit scale or real scale?

Okay so im confused! My real one (On flat surface says im 99-100). However, when i go on my wii fit on my carpet it says im lighter, like 94 and i realize that its cause of the carpet. When i got on my wii on a hard surface it says im hevier (102-103) The hard surface is a distance away from the tv tho. So which one do i trust? Thanks!