US paper sizes: Letter, Legal and Tabloid
If you are in the US or Canada, the sheet in your printer is almost certainly Letter: 8.5 × 11 inches (215.9 × 279.4 mm). It is what people mean by regular, standard or printer paper, and it is the default page size in Word, Google Docs and most printer drivers set up in North America.
- Legal is 8.5 × 14 in (215.9 × 355.6 mm): the same width as Letter, 3 inches longer. Contracts, real estate forms and some legal pads use it, although most US courts now ask for Letter.
- Tabloid is 11 × 17 in (279.4 × 431.8 mm), exactly two Letter sheets side by side. Ledger is the same sheet turned landscape, 17 × 11 in, which is why printer menus often list them together.
- Half Letter, also called Statement, is 5.5 × 8.5 in: a Letter sheet cut in half, common for booklets, planners and invoices.
- Executive is 7.25 × 10.5 in, an older size for personal stationery that still shows up in printer settings.
Regular paper is not 9 × 12 inches. A 9 × 12 sheet is Arch A, the smallest architectural size, and the usual size of construction paper and sketch pads. For anything you print at home or in an office in the US, start from 8.5 × 11.
For engineering drawings, the US uses the ANSI sizes from ANSI/ASME Y14.1: A (8.5 × 11), B (11 × 17), C (17 × 22), D (22 × 34) and E (34 × 44). Each one is the previous size doubled, so ANSI A and B are simply Letter and Tabloid. Architects use a separate set, Arch A to Arch E (9 × 12 to 36 × 48 in), with a 2:3 or 3:4 shape that suits building plans.
A sizes: A4, A3, A5 and the rest of ISO 216
Almost every other country, including the UK, uses the A series from ISO 216. A4 is 210 × 297 mm (21 × 29.7 cm, or 8.27 × 11.69 in), A3 is 297 × 420 mm and A5 is 148 × 210 mm.
The numbers look odd because the system is built on two rules. A0 has an area of one square meter, and every sheet has sides in the ratio 1:√2 (about 1:1.414). That ratio is the only one where cutting a sheet in half gives two sheets of the same shape, so A0 halves into two A1, A1 into two A2, and so on down to A10. The sizes are then rounded to the nearest millimeter.
The same rule makes scaling easy. Going up one size doubles the area, so A4 to A3 is always a 141% enlargement and A3 to A4 is 71%, whatever is on the page. Those are the presets on most photocopiers.
| Size | Millimeters | Inches | Typical use |
|---|---|---|---|
| A0 | 841 × 1189 | 33.11 × 46.81 | Technical drawings, large posters |
| A1 | 594 × 841 | 23.39 × 33.11 | Posters, flip charts, plans |
| A2 | 420 × 594 | 16.54 × 23.39 | Posters, art prints, display boards |
| A3 | 297 × 420 | 11.69 × 16.54 | Small posters, charts, menus, drawings |
| A4 | 210 × 297 | 8.27 × 11.69 | Letters, documents, printer paper |
| A5 | 148 × 210 | 5.83 × 8.27 | Flyers, notebooks, booklets |
| A6 | 105 × 148 | 4.13 × 5.83 | Postcards, pocket notebooks |
If you are wondering which is bigger, A3, A4 or A5: the lower the number, the bigger the sheet. A3 is twice A4, and A4 is twice A5.
B and C sizes: in between, and envelopes
The B series fills the gaps. Each B size is the geometric mean of two A sizes, so B5 (176 × 250 mm) is larger than A5 and smaller than A4, and B4 (250 × 353 mm) sits between A4 and A3. B sizes are common for books, notebooks, passports and posters. B0 is 1000 × 1414 mm.
The C series is for envelopes, sized to take an A sheet with a little room around it:
- C4 (229 × 324 mm) holds an A4 sheet flat.
- C5 (162 × 229 mm) holds A4 folded once, or A5 flat.
- C6 (114 × 162 mm) holds A4 folded twice, or A6 flat.
- DL (110 × 220 mm) holds A4 folded in three. A flyer that is a third of A4 (99 × 210 mm) fits inside it too.
One thing to watch in the US: envelopes sold as A2, A6 or A7 belong to a separate American system of announcement envelopes and have nothing to do with ISO A2, A6 or A7. Check the inches on the box.
Letter vs A4: what is the difference?
They look alike but are not interchangeable. A4 is 5.9 mm narrower and 17.6 mm taller than Letter, and about 3.4% larger in area.
| Letter | A4 | Difference | |
|---|---|---|---|
| Width | 8.5 in (215.9 mm) | 8.27 in (210 mm) | A4 is 0.23 in (5.9 mm) narrower |
| Height | 11 in (279.4 mm) | 11.69 in (297 mm) | A4 is 0.69 in (17.6 mm) taller |
| Aspect ratio | 1:1.294 | 1:1.414 | A4 is slimmer |
| Where it is standard | US, Canada, parts of Latin America | UK, Europe and most of the world |
Why the US never switched: Letter was already the standard office sheet long before ISO 216 was published in 1975, and printers, copiers, binders, folders and filing cabinets across the country are built around it. Changing the paper means changing all of that at once, so there is little reason for anyone to go first.
In practice this matters when a document crosses the Atlantic. A file laid out on A4 and printed on Letter loses about 18 mm at the bottom unless it is scaled down; a Letter layout printed on A4 gets cut at the sides. Two fixes work: let the printer driver shrink to fit (the page gets slightly smaller), or keep a margin of at least 20 mm (0.8 in) at the top and bottom and 15 mm (0.6 in) at the sides so the content fits on both sheets. The overlay in the tool above shows exactly where the two sheets differ.
Paper sizes in pixels
A paper size has no fixed size in pixels. Pixels depend on the resolution you will print or display at, measured in dots (or pixels) per inch: width in inches × DPI. The converter does this for any DPI; these are the four values people ask for most.
| DPI | Letter | A4 | Use it for |
|---|---|---|---|
| 72 | 612 × 792 px | 595 × 842 px | PDF points: the page size a PDF reports |
| 96 | 816 × 1,056 px | 794 × 1,123 px | Web pages: CSS defines 96 px per inch |
| 150 | 1,275 × 1,650 px | 1,240 × 1,754 px | Drafts, large posters seen from a distance |
| 300 | 2,550 × 3,300 px | 2,480 × 3,508 px | Print: flyers, brochures, photos |
For anything that will be printed and held in the hand, aim for 300 DPI at the final size. When you set up a document in Photoshop, Canva or Affinity, it is safer to enter the size in inches or millimeters and set the resolution to 300 than to type pixels: the app does the multiplication and the print size is exact. If you already have an image and want to know how large it can print, divide its pixels by 300 to get inches.
Setting up a file for print
A paper size is the trim size: the finished page after cutting. Commercial printers print on a larger sheet and cut it down, and the blade can drift by a fraction of a millimeter. Two settings protect your design from that:
- Bleed. Anything that touches the edge of the page, like a photo or a background color, should run past the trim line. US printers usually ask for 1/8 in (0.125 in) on each side and UK and European printers 3 mm, but always use the figure in your printer's file specs. The PDF button in the tool adds either and marks the trim size inside the file.
- Safe area. Keep text and logos well inside the trim, at least 1/8 in or 3 mm, and more for booklets where pages are bound. Otherwise a small shift in cutting can clip them.
Export the final file as a PDF at the trim size plus bleed, with images at 300 DPI at their printed size and colors set up the way your printer asks. If your brand colors need to look the same in print as on screen, the brand guidelines template keeps the screen and print values side by side, and the color palette generator exports them.
Methodology and limits
- Dimensions
- ISO A, B and C sizes are the millimeter values of ISO 216 and ISO 269. North American sizes are the inch values of ANSI/ASME Y14.1 for the ANSI sheets and the common trade definitions for Letter, Legal, Tabloid, Ledger, Executive, Half Letter and the Arch sheets. Nothing is rounded at the source: inch sizes are converted with 1 inch = 25.4 mm exactly, so their millimeter values are exact.
- Rounding
- Inches for metric sizes are shown to two decimals (A4 is 8.2677 in wide, shown as 8.27). Pixels are inches × DPI rounded to the nearest whole pixel, so a printed file at that DPI is within half a pixel of the true size.
- Comparison
- Both sheets are drawn to the same scale and aligned at the top left corner, in the orientation you picked. Differences are calculated from the exact millimeter values.
- A single blank page written in your browser, with the media box at trim size plus bleed and the trim and bleed boxes set to match (1 inch = 72 PDF points). It carries no marks or content, so it is ready to place artwork into.
- Limits
- Sheets bought in a shop can vary slightly from the nominal size: ISO 216 allows ±1.5 mm up to 150 mm, ±2 mm up to 600 mm and ±3 mm above that. Envelope sizes are the ISO C sizes; American announcement and commercial envelopes are not covered. Your choice of unit and DPI is remembered in this browser only, if storage is allowed.
Sources
- ISO 216:2007, Writing paper and certain classes of printed matter: Trimmed sizes, A and B series, and indication of machine direction, International Organization for Standardization
- ASME Y14.1, Decimal Inch Drawing Sheet Size and Format, American Society of Mechanical Engineers, for the ANSI A to E sheets
- International standard paper sizes, Markus Kuhn, University of Cambridge, on the A, B and C series, the √2 ratio and the C envelope sizes
- Paper size, Wikipedia, used as a secondary check for North American and architectural sizes
- CSS Values and Units Module Level 4: absolute lengths, W3C, for 1 in = 96 px = 72 pt = 25.4 mm
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