Announcement Envelope Guide

A2, A7, 4-bar.... huh?  The number of choices available for announcement envelopes can be a little overwhelming and even confusing.  Here's some information and a handy guide to help you choose the right envelopes for the project:

A1 (4-bar) - Response card or note card

• Envelope size - 3.625”x 5.125” 
• The smallest size the USPS will deliver with standard postage
• Folded card or flat card insert size - 3.5" x 4 7/8"

A2 

• Envelope size - 4.375" x 5.75"
• Common size for quarter or half sheet (folded) cards
• Folded card or flat card insert size - 4.25" x 5.5"

A6 

• Envelope size - 4.75" x 6.5"
• Folded card or flat card insert size - 4.5" x 6.25"
• Great for formal and informal announcements, also holds standard 4" x 6" photo prints
• Can be used as an inner envelope as it fits inside A7, A8 and A9 envelopes

A7 

• Envelope size - 5.25" x 7.25"
• Folded card or flat card insert size - 5" x 7" or 5 1/8" x 7"
• The classic announcement envelope size, perfect for formal invitations
• Can hold 5" x 7" photos

A8  

• Envelope size - 5.5" x 8.125"
• Folded card or flat card insert size - 5.125" x 7.75
• Can be used for outer envelope for A6 or A7 inner envelopes

A9  

• Envelope size - 5.75" x 8.875"
• Folded card or flat card insert size - 5.5" x 8.5"
• Accommodates two flat, or one folded from a 8.5" x 11" letter-sized sheet of cardstock 

Here's some additional information from the United States Postal Service

• Maximum weight is 3 1/2 oz.
• Must be rectangular.
• Minimum size is 5" long x 3 1/2" high x 0.007” thick.
• Maximum size of 11 1/2" long x 6 1/8" high x 1/4” thick.
• Maximum weight is 3.5 oz.
• A letter will be charged a non-machinable surcharge if it’s a square letter 5" x 5" or larger, it doesn't bend easily, has clasps or similar closure devices, has an address parallel to the shorter dimension of the letter, is lumpy, or the length divided by height is less than 1.3 or more than 2.5.