I don't think it's necessary... People are used to seeing measurements of size as length x width (or width x length) and not multiplying them into area. We say photos are 5x7, standard-sized notebook paper is 8.5x11, index cards are 3x5, etc. We know what that terminology means. On the other hand, I guess it couldn't hurt to be more specific. But I don't think it's unclear the way it is.
Kaylle
