6×9 envelope: size, uses and how to print it

What a 6×9 envelope is for

A 6×9 envelope is built around one job: carrying US Letter paper folded once. Folded in half, an 8½ × 11 in sheet becomes a 5½ × 8½ in page, which slides in with a little room on every side, so nothing gets bent on the way in. That makes it the usual envelope for half-letter booklets such as concert programs, church bulletins, small catalogs and printed newsletters.

It also fills the gap between two envelopes most people already use. A #10 business envelope needs the sheet folded in three, which looks cramped for a brochure or a letter with photos, while a 9×12 envelope takes Letter paper flat but always mails in the more expensive large format. The 6×9 gives you a single fold, a roomy front for the address and, as long as the contents stay thin, the cheaper letter rate.

What fits inside

The simplest measure is sheets of Letter paper folded once. A few sheets folded together fit comfortably, and so does a stapled booklet made from them, as long as it doesn't make the envelope bulge. Flyers and forms printed at half-letter size go in flat, and so do folded cards of 5½ × 8½ in, although a card has some play in here and a card envelope looks more finished.

An A5 sheet or A4 folded once fits too, but with only a few millimeters to spare across the width, so a C5 envelope suits that fold better. The 6×9 is also a flat envelope without a gusset, which means it's made for paper rather than objects. Adding a pen, a USB stick or a fridge magnet strains the seams and can change how the envelope is charged.

Letter or large envelope at the post office

In the US the post office prices mail by shape as well as weight. A 6×9 envelope counts as a letter while it stays thin and light: four sheets of Letter paper folded once plus the envelope weigh about 25 g, just under an ounce, and are about a millimeter thick, so they go at the letter rate. USPS sets the letter limits like this: Up to 11½ × 6⅛ in, ¼ in thick, 3.5 oz. Add more pages until the mailing is thicker or heavier than that, and it becomes a large envelope, which USPS calls a flat and charges more for. With ordinary paper you usually reach the weight limit before the thickness limit, which is why weighing the envelope comes first.

A pen, key or coin inside, or a metal clasp or string-and-button closure, makes a thin envelope a nonmachinable letter, which pays a surcharge because the letter-sorting machines can't handle it. A booklet with stiff covers that doesn't bend easily also counts as a nonmachinable letter and pays the surcharge, even when it's thin and light enough for a letter. The direction of the address matters too: for the plain letter rate it has to run along the long side, so a catalog envelope addressed upright, with the lines running along the short side, is nonmachinable as well. If the envelope is also too thick for a letter, it can still go as a large envelope as long as it stays flexible and evenly thick, but a pen, key or coin that makes it lumpy turns it into a package, which costs more again.

In the UK the logic is the same under Royal Mail's names, and a Letter has to stay within these limits: Up to 24 × 16.5 cm, 5 mm thick, 100 g. A 6×9 is small enough for that when the contents are thin and light, and becomes a Large Letter when they're thicker or heavier. A pen, a USB stick or a chunky card usually makes it too thick for a Letter even when it weighs very little, so it needs a Large Letter stamp. In both countries, weigh the finished envelope on a kitchen scale and measure its thickness at the thickest point before you buy stamps, because the post office's own scale and size check have the final word.

Printing the address at home

The long side of a 6×9 envelope is wider than most home printers can take, so it goes in short edge first, ideally through the rear or manual slot, whose straighter path is kinder to thick envelopes. Which way the flap should face differs between printers, so check the envelope symbol on the tray or run a test on plain paper with an arrow drawn at the top. In the print dialog, choose the matching envelope size or a custom size, print at 100% rather than "fit to page", and switch the orientation if the test comes out sideways.

The button on this page opens the editor with the envelope set to Booklet 6 × 9 in, your return address top left, the recipient in the middle and the stamp corner left free. Type the addresses, choose a font, and print directly or export a PDF whose page is exactly the envelope's size. If your printer won't take the envelope, or you're mailing a whole list, print address labels instead, for example 30 to a Letter sheet in Avery® 5160 size. With a free account you can import the list from a spreadsheet and get one envelope or label per address, and the guide to printing envelopes at home walks through it step by step.