If I recall right, A3 is 11x17"...strange proportions for typical images, but I suppose the amount of page you use would depend on the image shape itself. Perhaps 10" wide...and using the nifty forumula, that'd be 10 * 300 = 3000 pixels...then the height would depend on the image's proportions, up to (16*300) 3900p. Check my math; I don't trust it. LOL! :)