What Size Are Thank You Cards? Complete Guide

The A1 is the smallest standard thank you card. It is compact, personal, and perfect for short messages like a line after a networking coffee or a quick note dropped in a shipping box. This size fits an A1 envelope at 3.625 by 5.125 inches and mails with a standard first-class stamp.

It is a favorite for brief thank-you notes after meetings, small gift acknowledgments, and product-packaging inserts, because it slips into a box without adding bulk. If you are building branded packaging to go with it, our guide on how to make envelopes walks through custom-sized options that pair neatly with the A1.

Slightly larger than the A2, the A6 card gives you more room for design without jumping all the way to a 5 by 7. This size works well when you want to add a small photo, a logo, or a decorative border alongside your message. It pairs with an A6 envelope at 4.75 by 6.5 inches.

It shines for branded business thank-you cards that need clean logo placement, photo cards like a wedding shot on the front, and bilingual messaging where every line needs a little more breathing room. That extra half inch in each direction makes a real difference when your design cannot afford to feel crowded.

Here is where people get tripped up. A 5 by 7 folded thank you card starts as a 10 by 7 inch flat sheet that folds in half to become 5 by 7. The finished size, what the recipient holds, is 5 by 7. But your design file has to be built at 10 by 7 with a fold line down the center.

The same logic applies to a 4.25 by 5.5 folded card, which starts as an 8.5 by 5.5 flat sheet. Always confirm whether a listed size refers to the finished folded dimensions or the flat sheet, because getting it wrong prints your design at the wrong scale. Our folded thank you cards handle this for you, and if you enjoy hands-on paper projects, how to fold a brochure covers folds that apply to card stock too.

Flat cards are single or double-sided prints with no fold, which keeps them simpler, cheaper, and great for quick notes or postcard-style cards. Folded cards give you four panels, front, inside left, inside right, and back, for longer messages and a more traditional greeting-card feel. Our flat thank you cards cover the postcard-style side of that choice.

Every standard card size has a matching envelope, and the envelope should sit about a quarter inch larger than the card on each side. Here is the quick reference to keep the two in step.

• 3.5 by 5 card uses an A1 envelope at 3.625 by 5.125 inches.
• 4.25 by 5.5 card uses an A2 envelope at 4.375 by 5.75 inches.
• 4.5 by 6.25 card uses an A6 envelope at 4.75 by 6.5 inches.
• 5 by 7 card uses an A7 envelope at 5.25 by 7.25 inches.

A card that sits too tight in its envelope looks cheap and arrives wrinkled. A card swimming in an oversized envelope feels careless. Get the pairing right and the whole package reads as intentional, which is exactly the impression a thank-you card is meant to leave.

Even small errors in card sizing lead to big problems. These are the mistakes people make most often when they are working out what size a thank you card should be, and how to sidestep each one.

• Confusing flat size with folded size. A 5 by 7 folded card needs a 10 by 7 design file. Set it up at 5 by 7 and it prints at half scale.
• Forgetting the bleed area. Add an eighth of an inch of bleed on all sides. Without it you get white edges where the card is trimmed.
• Ignoring envelope compatibility. Order cards without checking envelope sizes and you are scrambling for custom sleeves later.
• Choosing a size too small for the message. If your note runs more than a few lines, size up so the words can breathe.
• Skipping a physical proof. Screens lie about scale, so hold the real card before you print hundreds.

None of these are hard to avoid once you know they exist. Confirm the finished size, build in the bleed, match the envelope, and approve a proof, and your thank you cards land exactly the way you pictured them.