Standard Mail is divided into two primary shapes: “letter-size” and “flats”. Letter-size has maximum dimensions of 6.25″ x 11.5″ with an aspect ration of 1:1.3 – the ratio of the height to the width. In essence, it is always rectangular. A mail piece is considered a “flat” if either of its dimensions are larger than letter-size.
Postage for letter-size mail is determined by piece rate. Postage for flats is determined by piece rate plus a weight rate calculation. Every Door Direct Mail pieces are always considered flats; however their postage is determined by a piece rate schedule only.
There are many EDDM sizes available to you, but we suggest using 6.5″ x 9″, 6.5″ x 11″ or 8.5″ x 11″. It is even possible to use an 11″ x 17″ folded vertically to 8.5″ x 11″.