Letterhead Paper Size Guide

Letterhead paper size is regional before it's stylistic. Pick the wrong one and your carefully designed layout either gets cropped at the printer, or leaves an odd, unintentional band of white space at the bottom of the page. It's one of the few letterhead decisions that has a genuinely correct answer for most people, based entirely on where they operate — so it's worth understanding where each size actually comes from, not just what its dimensions are.

A4 — the ISO 216 standard

A4 (210 × 297 mm, 8.27 × 11.69 in) is defined by the ISO 216 international paper size standard, which is built on a genuinely elegant piece of geometry: every "A" size has the same aspect ratio (1:√2, roughly 1:1.414), so folding an A-size sheet in half along its long edge produces the next size down with the identical proportions. Fold an A3 sheet in half and you get A4; fold A4 in half and you get A5. This is why A4 photocopies and scales so predictably — it's mathematically self-consistent in a way US paper sizes are not. A4 is the standard letterhead size across the UK, the EU, most of Asia, Australia and the majority of the world outside North America.

US Letter — the ANSI standard

US Letter (8.5 × 11 in, 215.9 × 279.4 mm) is defined by the ANSI/ASME Y14.1 standard and is the everyday paper size in the United States, Canada and parts of Latin America. Unlike the ISO system, ANSI sizes don't share a single fixed aspect ratio across the whole series, which is part of why US Letter, Legal and Executive all have visibly different proportions rather than being clean multiples of one another. US Letter is slightly wider and noticeably shorter than A4 — a letterhead designed against A4 margins will have its bottom content pushed close to (or off) the edge if printed on US Letter without adjustment.

Legal — for longer formal documents

Legal (8.5 × 14 in, 215.9 × 355.6 mm) shares the same width as US Letter but is three inches taller. It's used in the US for longer formal documents — contracts, legal notices and multi-clause agreements — specifically to avoid awkward page breaks partway through a clause. It's not a common everyday letter size, but law firms and any business that regularly sends longer contracts often keep a Legal-size letterhead alongside their standard US Letter one.

A5 — half of A4

A5 (148 × 210 mm) is exactly half of an A4 sheet, by the same fold-in-half logic described above. It's used for short notes, compliment slips and small printed cards rather than full letters, and it's also a natural fit for lighter, more personal formats — a short note from an individual, or a printable card for a small keepsake message, where a full A4 page would feel oversized for the amount of text involved.

Executive — a smaller US format

Executive (7.25 × 10.5 in, 184 × 267 mm) is a slightly smaller US paper size, sometimes used for personal or executive correspondence where a full Letter-size page feels too large for a short, personal note. It's less commonly available as a pre-cut office paper stock than US Letter, so it's worth confirming a print shop or office supplier actually stocks it before designing extensively around it.

Full comparison table

How to tell which size your country uses

• International business correspondence, or based outside North America → A4.
• Based in the United States or Canada → US Letter.
• Sending contracts and long legal documents in the US → Legal, alongside a standard US Letter version.
• Sending short notes, compliment slips or small printables anywhere → A5.
• Personal executive correspondence in the US → Executive, if your printer stocks it.

What happens if you print the wrong size

Printing an A4-designed letterhead on US Letter paper (or the reverse) doesn't just look slightly off — most printer drivers will either scale the whole page down to fit, shrinking your carefully sized logo and margins along with it, or crop the page and lose content entirely along one edge. Consumer printers set to "fit to page" will silently rescale everything, which is the more common outcome and also the harder one to notice at a glance, since nothing is obviously missing — it just looks marginally wrong in a way that's hard to place.

Converting between paper sizes without breaking your design

Because A4 and US Letter have different aspect ratios (not just different absolute sizes), a design that fills an A4 page edge-to-edge will never map perfectly onto US Letter — something has to give, usually a small amount of extra white space at the bottom of the taller of the two. The reliable way to switch is to let the layout tool recalculate margins and element positions for the new page size, rather than manually stretching a fixed-size export. In the Letterheads editor, switching paper size under the Layout tab does exactly this: it keeps your logo, colours and fonts, and recalculates spacing for the new dimensions rather than distorting the existing design.

DPI, resolution and print quality basics

DPI (dots per inch) measures how much detail a printed image carries per unit of physical size — the higher the number, the sharper fine details like small text and logo edges appear. Screens typically render at 72–96 DPI, which is perfectly sharp on a monitor but visibly soft once printed, because a printer is packing far more physical dots into the same inch of paper than a screen displays pixels. The commercial print standard is 300 DPI; anything designed or exported below that will look noticeably fuzzier on paper than it did on screen, especially for small footer text and fine divider lines.

Matching envelope sizes to your letterhead

A letterhead is only half of a physical mailing — the envelope needs to match, or a nicely folded letter ends up cramped or rattling loose inside. The pairing follows the same regional split as the paper itself.

DL and #10 are the standard "everyday letter" envelopes for A4 and US Letter respectively, both sized for a tri-folded sheet. If your letterhead has an important visual element near the very top or bottom of the page, it's worth checking where the fold lines fall — a tri-fold divides the page into three roughly equal horizontal bands, and a logo or signature sitting exactly on a fold line will get a visible crease through it.

Every paper size in this guide is available as a one-click option under the Layout tab in the Letterheads editor, so it's safe to design first with whichever size feels right and confirm — or change — the exact paper size right before you export.