The 6 Booklet envelope has a width of 8.875 inches and a height of 5.75 inches, giving it a total surface area of 51.01 square inches. Its maximum enclosure size is 5.5 x 8.625 inches. This booklet envelope is sometimes referred to as the 6-1/4 booklet envelope, corresponding to its width dimension.
Booklet envelopes like the 6 get their sizing from their height in inches rather than a numbering convention. The 6 booklet envelope is designed with an open side seam to easily insert booklets, brochures, catalogs and other documents without folding. Its compact width combined with ample height provide an efficient fit for small booklets and pamphlets. The open side alleviates wear and tear from folding. The 6 booklet envelope offers a roomy option for mailings that require protective flat insertion of content.