What is the biggest size my invitation can be to fit into an A7 envelope?

An A7 envelope measures 5 1/4 x 7 1/4 inches, so the largest card that slides in comfortably is about 5 x 7 inches.

• Leave roughly 1/8 to 1/4 inch of clearance so the card goes in and out easily.
• A 5 x 7 invitation is the classic pairing for an A7 envelope.
• If your card is larger than 5 x 7, step up to an A8 or A9 envelope.