DPI Vs Megpixels Info

The printing company I use normally print at 72 dpi for a canvas (though they will go higher if you request it). Therefore it depends on how many MP your camera is and what size images you can produce at 72 dpi as to how large a canvas you can get.

For example, my camera (8.2 MP) takes photo's which are 3504 x 2336 (largest). This would produce a 48.7 x 32.4 inch print at 72 dpi. The more I increase the dpi, the smaller the print, so at 180 dpi I can only produce a 19.5 x 13 inch print.

HTH