How to Use the Envelope Size Guide
Choosing the wrong envelope means folding your document more than necessary or paying extra postage for excess size. This guide shows the exact dimensions of the most common U.S. envelope catalog sizes so you can match your paper and mailing needs before you buy or print.
The #10 business envelope (4.125 × 9.5 in) is the default for a standard 8.5×11in letter folded in thirds — used for bills, business correspondence, and most everyday mail. A2 (4.375 × 5.75 in) and A6 (4.75 × 6.5 in) envelopes are sized for cards rather than letters, with A6 being the larger of the two and popular for wedding invitations. If you need to send an 8.5×14in legal document without folding it, a Legal envelope at 9.5 × 15 in is the right choice. Always confirm with USPS for postage rates, since envelope thickness and weight affect the final cost regardless of size.
Frequently Asked Questions
A #10 business envelope (4.125 × 9.5 in) fits an 8.5×11in letter folded in thirds — the most common size for business mail. For unfolded 8.5×14in legal paper, use a Legal envelope (9.5 × 15 in).
A2 (4.375 × 5.75 in) is sized for small cards like RSVP or note cards, while A6 (4.75 × 6.5 in) is larger and commonly used for greeting cards and wedding invitations.