How to use
- 1
Enter the size of what you are mailing.
- 2
Add the thickness if known.
- 3
Read the best fit and mail class.
When to use it
Invitations
Find the A7 for 5×7 cards.
Business mail
Use a #10 for tri-folded letters.
Documents
Pick 9×12 for flat letters.
Good to know
- Leave 1/8 inch on each side.
- A #10 fits a letter folded in thirds.
- Square envelopes cost more to mail.
FAQ
What size is a #10 envelope?
4-1/8 × 9-1/2 inches.
5×7 card envelope?
A7 (5-1/4 × 7-1/4).
Letter vs flat?
Over 6-1/8 × 11-1/2 or 1/4 inch thick is a flat.