Paper Sizes Explained: Letter, Legal, A4, and A5
US Letter (8.5 × 11 in / 215.9 × 279.4 mm) is the standard for everyday documents in the US, Canada, and a handful of other countries; nearly everywhere else defaults to A4 (210 × 297 mm), one step down from A3 in the international ISO 216 series. The two are close in total area but not interchangeable at 100% scale — printing a Letter PDF on an A4 tray (or the reverse) clips part of the page unless you handle the mismatch on purpose. Here's every common size, who uses what, and how to move a PDF between them without distorting anything.
Last updated: August 24, 2026
The exact dimensions
All five sizes you'll actually run into for printables, in inches, millimeters, and PDF points (72 points per inch — the unit Printable Mill's PDFs are built in natively):
- US Letter — 8.5 × 11 in / 215.9 × 279.4 mm / 612 × 792 pt. The default for nearly everything printed at home or in an office in the US.
- US Legal — 8.5 × 14 in / 215.9 × 355.6 mm / 612 × 1008 pt. Same width as Letter, 3 in taller.
- Half Letter (Statement) — 5.5 × 8.5 in / 139.7 × 215.9 mm / 396 × 612 pt. Letter cut exactly in half along the long edge.
- A4 — 210 × 297 mm / 8.27 × 11.69 in / 595.28 × 841.89 pt. The default nearly everywhere outside North America.
- A5 — 148 × 210 mm / 5.83 × 8.27 in / 419.53 × 595.28 pt. A4 cut exactly in half along the long edge.
All Printable Mill tools let you choose the target paper size before generating the PDF, so you never have to rescale after the fact — pick the size that matches what's loaded in your printer tray and every dimension comes out exact.
Why the US uses Letter and everyone else uses A4
The ISO 216 standard (adopted internationally in 1975, based on a German DIN standard from 1922) defines the A series with a fixed aspect ratio of 1:√2 (about 1:1.414). That single ratio is the whole trick: cut any A-size sheet exactly in half across its long edge and you get the next size down at the identical proportions — A4 folded in half is A5, A3 folded in half is A4. That's also why enlarging or reducing between adjacent A sizes on a photocopier at a clean 141% or 71% preserves the page proportions exactly.
US Letter has no such relationship. It descends from a 1921 American standards decision tied to historical papermaking mould sizes, not a geometric ratio, so Letter, Legal, and Tabloid (11 × 17 in) don't share proportions the way A4, A3, and A5 do. Legal is simply Letter with 3 extra inches added to one edge — not a proportional scale-up.
Letter vs A4 — the practical difference
Letter is 215.9 mm wide against A4's 210 mm — Letter is 5.9 mm wider. But Letter is only 279.4 mm tall against A4's 297 mm — Letter is 17.6 mm shorter. In other words, Letter is a slightly shorter, slightly wider rectangle than A4; neither dimension of one fully contains the other. Total area is close: A4 is about 623.7 cm² and Letter is about 603.2 cm², so A4 is roughly 3.4% larger overall, but that similarity in area is exactly what makes the size confusable — the actual shape doesn't match.
How to print a Letter PDF on A4 paper (or A4 on Letter) without distorting scale
There are two honest ways to handle a size mismatch, and one dishonest one to avoid.
Best option: regenerate the PDF at the paper size you'll actually print on. Every Printable Mill tool has a paper-size picker before download — set it to match your printer tray (Letter, Legal, A4, or A5) and the output is built for that exact page from the start. No cropping, no blank margin, no math required.
If you're stuck with a fixed PDF in the "wrong" size, set the print dialog's scale to 100% / Actual size — never "Fit to page." At 100%, the printer centers the content and either clips a sliver of the outermost edge or leaves a blank margin, depending on which dimension is larger. Letter on an A4 tray: the right edge loses about 5.9 mm, the bottom gains about 17.6 mm of blank space. A4 on a Letter tray: the sides gain about 5.9 mm of margin combined, the bottom loses about 17.6 mm. Most templates keep real content well inside a safety margin, so the clipped sliver is usually empty space — but check anything with a full-bleed border, like a certificate.
What not to do: never use "Scale to fit paper" as a substitute for a size mismatch. That setting resizes every element by the same percentage rather than cropping or padding — which is exactly what turns a 1 cm grid square into a 0.97 cm square. See How to Print at Exact Scale for the full breakdown of scale settings by browser.
Legal size — when it's actually needed
US Legal is Letter's taller sibling: same 215.9 mm width, but 355.6 mm long instead of 279.4 mm — about 3 in / 76 mm taller. It's used almost exclusively in the US for contracts, legal pleadings, and some government forms. Most consumer printers support it as a tray option, but it's genuinely rare outside legal paperwork. Only pick Legal if the finished document has to match a Legal-format form it accompanies — for a to-do list, graph paper, or habit tracker, the extra length just wastes paper.
A5 — the half-size option
A5 (148 × 210 mm / 5.83 × 8.27 in) is exactly A4 cut in half along the long edge, and it's the standard size for pocket notebooks, compact planners, and flyers across most of the world. Because of that exact 1:2 relationship, two A5 pages printed 2-up on one A4 sheet and cut down the middle produce a clean small-planner insert with no wasted margin. Printable Mill's planner tools support A5 directly, so there's no need to print at A4 and trim by hand — though doing so with a paper cutter is fine if you want sharper edges than scissors give.
Half Letter / Statement — the US equivalent
Half Letter (5.5 × 8.5 in / 139.7 × 215.9 mm) is Letter cut in half the same way A5 relates to A4. It's also called "Statement" size, and in the personal-organizer world it's the classic ring-binder page used by Franklin Covey Classic and Filofax Personal systems. For a 5.5 × 8.5 in ring binder, pick Half Letter specifically, not A5 — the two are close (139.7 × 215.9 mm vs. 148 × 210 mm) but not identical, and a page cut to the wrong one won't sit flush against rings punched for the other.
Can I just print an A4 PDF at 100% on Letter paper and trim the edge?
Yes, but you'll lose about 17.6 mm off the bottom of the page in the process. It's cleaner to regenerate the PDF at Letter size directly using the paper-size picker on the tool you used, if one is available.
Is A4 bigger or smaller than Letter?
By total area, A4 is about 3.4% larger. But it's not simply "bigger" — A4 is narrower and taller than Letter, so neither size fully contains the other's footprint. That's why converting between them always involves a small clip on one dimension and a small margin on the other.
What paper size should I use for graph paper meant for a US 3-ring binder?
Letter. Standard US ring binders are punched to match 8.5 × 11 in sheets, and using A4 instead would put the holes in the wrong position relative to the page edge.