A8 envelope size and what fits in it
An A8 envelope measures 139.7 × 206.4 mm (5½ × 8⅛ in). It sits between the A7 and the A9, so it's the envelope for cards a little bigger than 5×7 but shorter than a half-letter card.
- Size
- 139.7 × 206.4 mm (5½ × 8⅛ in)
- What fits
- Cards up to 5¼ × 7⅞ in
- Printing
- Fits most home printers; the icon on the paper tray shows which way round to feed it.
- Also called
- a8
What an A8 envelope is for
The A8 is one of the US announcement envelopes, the family of card and invitation sizes that runs from the small A1 up to the long A10. At 139.7 × 206.4 mm (5½ × 8⅛ in), it is a step up from the A7 that most 5×7 cards come with and a step down from the A9. That in-between size is its whole job, because it holds cards that are a little too big for an A7, which you mostly meet in invitation sets, wedding stationery and handmade cards.
Because the A8 is less common than its neighbors, stores carry fewer of them and the choice of colors and liners is smaller. So it's worth measuring your card before you order envelopes rather than going by what the card is called.
A7, A8 or A9: which one your card needs
The three sizes are close enough to mix up, so compare your card with what each envelope is made for:
| Envelope | Made for |
|---|---|
| A7 | 5×7 cards |
| A8 | Cards up to 5¼ × 7⅞ in |
| A9 | Half-letter cards (a sheet of US Letter cut in half) |
A 5×7 card does go into an A8, but it slides around and looks lost when the envelope is opened, so the A7 envelope is the better match. A card made for the A8 won't go into an A7 at all, and a half-letter card is longer than the A8 itself, which is why it needs an A9 envelope.
Thickness counts as well as size. A folded card on heavy stock, a vellum wrap or a reply card tucked behind the invitation all take up room, and an envelope bulges when the card already fills it edge to edge. If you're between two sizes, take the larger envelope, because a slightly loose card looks fine while a tight one bends at the corners or strains the seams.
Printing the address on an A8 at home
An A8 is an easy envelope for a home printer, because even its long side is narrower than a sheet of US Letter, the widest paper most home printers take. Printers differ in which way round they want envelopes fed and which side the flap should face, so check the icon on the paper tray or the manual, and try it once on plain paper cut to the envelope's size. In the print dialog, choose the envelope size, or set a custom paper size of 139.7 × 206.4 mm (5½ × 8⅛ in) if your printer doesn't list A8, and print at 100%, not "fit to page", so the address lands exactly where you placed it.
The button on this page opens the label editor at the A8 size, with the return address and recipient blocks already in place, and you can print directly or export a PDF exactly the size of the envelope. For a guest list, import the addresses from Excel or a CSV file and print one envelope per guest; that mail merge needs a free account. If your printer won't take thick or lined envelopes, print address labels on a sheet instead; the guide to printing envelopes at home covers both routes.
How an A8 envelope is mailed in the US and UK
USPS mails a rectangular paper envelope within these limits as a First-Class Mail letter: Up to 11½ × 6⅛ in, ¼ in thick, 3.5 oz. An A8 is well inside the length and height, so when you address it along its long side, weight and thickness decide the price, unless the invitation is stiff or lumpy: USPS charges the non-machinable surcharge for envelopes that are rigid or lumpy or have clasps, string or buttons, and asks you not to put rigid objects such as coins, keys or flash drives in a letter. Addressed vertically, as on many invitations, it pays the non-machinable surcharge of $0.49 on top, because USPS also charges more for envelopes that are square or vertical (taller than they are wide). For example, a flat invitation on heavy card stock, addressed along the long side, weighs about half an ounce and needs one Forever stamp, but a reply card in its A2 envelope can push it past the first ounce, so it needs postage for a second ounce.
Decorated invitations have their own rules: for specially decorated envelopes, USPS lets you pay the non-machinable surcharge and ask the Post Office counter to hand-cancel them, and for wax seals, strings, ribbons and other decorations on the outside it advises not to send them exposed but to put the envelope inside another envelope. A pocket-fold suite too thick for the letter limit can go at the higher large envelope (flat) price only if it meets these conditions: bigger than a letter, up to 15 × 12 in, ¾ in thick, 13 oz; must be flexible and evenly thick. A suite that is too thick for a letter and also rigid or lumpy is priced as a package instead, so have one finished envelope priced at the post office counter before you stamp the whole batch.
Royal Mail's limits for an ordinary Letter are: Up to 24 × 16.5 cm, 5 mm thick, 100 g. An A8 fits them easily, so it takes a standard 1st or 2nd Class stamp unless a wax seal, a ribbon or a chunky handmade card makes it too thick, which turns it into a Large Letter. The stamp calculator estimates the price by weight for either country.
Print the addresses instead of writing them
The free label editor opens at the size of your envelope (A8 (5½ × 8⅛ in)) with a sender and a recipient block. Type one address and print it, or import your address list with a free account and print one envelope per address. It runs in your browser: nothing to install.
Print on this envelope →FAQ
Does the A in A8 have anything to do with A4 or A5 paper?
No. The A in the US card envelope sizes stands for announcement, and the numbers have nothing to do with the ISO A series of paper used in the UK and Europe. The ISO envelope sizes are the C series instead, and an A8 falls between C6 and C5. If you buy A8 envelopes from a UK shop, check the measurements in the listing to be sure you're getting this US size.
Will an RSVP envelope fit inside an A8 invitation?
Yes. The usual reply envelopes, A1 (4 Bar) and A2, are both much smaller than an A8, so one lies flat behind the invitation with room to spare. The extra card and envelope do add weight, though, as the postage example above shows.
Can I send an A8 card abroad?
Yes, as an international letter, which costs more than domestic postage. From the US the price depends on the destination group and the weight, and a Global Forever stamp covers the first ounce to any country for a card addressed along its long side. USPS charges the non-machinable surcharge on letters to other countries too, whatever they weigh, if the envelope is square or nearly square or the address runs parallel to its short side, or if it is rigid, unevenly thick or has clasps, string or buttons, so have a vertically addressed or decorated invitation priced at the Post Office counter. The US stamp prices page lists the prices by country group. From the UK, Royal Mail is clear that 1st Class UK postage is not enough for post to any overseas destination, so use the International Standard letter price on the UK stamp prices page (same price to Europe and the rest of the world) as long as the card stays within the Letter limits. A card too thick for a Letter goes as an International Large Letter, which is priced by weight and destination.
Which font looks good on an A8 invitation envelope?
Script fonts such as Great Vibes, Sacramento or Dancing Script give an invitation a handwritten look, and the editor has them alongside serif fonts like Playfair Display and EB Garamond. Keep the guest's name decorative if you like, but set the street, city and ZIP code in something plainly readable, because the post office reads those lines by machine. Print one test envelope and check that a stranger could read it at a glance.
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Updated 8 November 2026