size of bmp while texture mapping

i want to know what should be the maximum size of bmp file while mapping. what should be it’s format 16-bit or 32-bit
( my card supports 16 & 32 bit )

I’d advise you to stick to 16 bit for speed and compatibility reasons.

As for the size, you want to stick to a power of two. If possible all textures should be no more than 256256. I normally use 128128 or 256*256 for my textures.