Security Envelopes Size Guide
Not sure what size you need? Our size guide can help you pick the right envelope, for the right reason.
The most common size security envelopes is the #10. This is a standard envelope size, and the most popular for sending documents, invoices, statements, or other materials. If you are mailing a check, you may want to choose 8 5/8 or #9. If you're unsure which size you need, simply measure the item and choose an envelope that is at least 1/16" to 1/8" larger than the insert.
Security Envelope Sizes
- #6 3/4 (3 5/8 x 6 1/2) - Fits a personal check, plus a small insert - up to 3 1/2 x 6 1/4.
- #8 5/8 (3 5/8 x 8 5/8) - Ideal for many printed commercial and business checks.
- #9 (3 7/8 x 8 7/8) - Return envelope. Fits comfortably inside a standard #10 envelope.
- #10 (4 1/8 x 9 1/2) - Standard business envelope. Fits an 8 1/2 x 11 piece of paper folded in thirds.
- 6x9 Security Envelope - Fits up to a 5.85 x 8.85 insert. Typically used for small catalogs, brochures, or folded paper.
- 9x12 Security Envelope -Fits up to a 8.75 x 11.75 insert. Typically used for standard catalogs, or several sheets of paper.
- 10x13 Security Envelope -Fits up to a 9.75 x 12.75 insert. Commonly used for larger catalogs, or with a 9x12 envelope.