A paper size chart lists every standard sheet dimension in one place — in millimetres, centimetres, inches, and pixels at any chosen DPI — so A4 (210 × 297 mm), US Letter (8.5 by 11 in), and A3 (297 by 420 mm) can be compared at a glance. The chart works because paper standards are based on simple maths: ISO 216, the international system, defines every A and B sheet with a height-to-width ratio of the square root of two (about 1.414), which means folding any sheet across its longer side produces two copies of the next smaller size with the same proportions. North America uses its own ANSI-based system, where US Letter is 8.5 by 11 inches (215.9 by 279.4 mm), US Legal is 8.5 by 14 inches (215.9 by 355.6 mm), and Tabloid, also called Ledger, is 11 by 17 inches (279.4 by 431.8 mm). Because all of these sizes can be expressed in millimetres, centimetres, and inches, a single chart can replace three or four separate reference tables. Add a pixel column at a chosen DPI and the chart becomes a setup sheet for designers, print buyers, and anyone who has ever guessed whether A4 is bigger than Letter. The Paper Sizes Chart pairs exactly that reference grid with a live converter that turns any size into pixel dimensions at the resolution you type.
The ISO 216 system: A and B series
The international paper standard is ISO 216, which defines the A series used in nearly every country outside North America and the B series used for posters, books, and envelopes. Its defining trick is the aspect ratio: every sheet has a height-to-width ratio of √2 (about 1.414). Because of that constant ratio, folding a sheet in half across its longer side produces two sheets of the next size down, each keeping the same proportions. The series is anchored by A0, which has an area of almost exactly one square metre and measures 841 by 1189 millimetres. Halving A0 gives A1 (594 by 841 mm), then A2 (420 by 594 mm), A3 (297 by 420 mm), and the everyday A4 at 210 by 297 mm, continuing down to A10. That same halving rule means A4 is exactly the same shape as A0, A1, A2, A3, A5, and so on, which is why a Word document formatted for A4 prints correctly on A3 with proportional margins and why scaling artwork between A sizes never distorts it.
The B series sits one geometric step between the A sizes. B0 measures 1000 by 1414 millimetres (a little larger than A0), and each subsequent size follows the same √2 halving rule. B sizes are useful when an A size is too small but the next A size up is too large: posters, book covers, and envelopes often call for B4, B5, or B6 because they fall neatly between A sizes. In a paper size chart, B entries usually appear alongside A entries so the reader can pick the closest fit without re-measuring. B5, for example, is the standard pocket-book trim size in much of Europe, and it is roughly halfway between A4 and A5 in both dimensions.
| Size | Millimetres (W × H) | Centimetres (W × H) | Inches (W × H) |
|---|---|---|---|
| A0 | 841 × 1189 | 84.1 × 118.9 | 33.1 × 46.8 |
| A1 | 594 × 841 | 59.4 × 84.1 | 23.4 × 33.1 |
| A2 | 420 × 594 | 42.0 × 59.4 | 16.5 × 23.4 |
| A3 | 297 × 420 | 29.7 × 42.0 | 11.7 × 16.5 |
| A4 | 210 × 297 | 21.0 × 29.7 | 8.3 × 11.7 |
| A5 | 148 × 210 | 14.8 × 21.0 | 5.8 × 8.3 |
| A6 | 105 × 148 | 10.5 × 14.8 | 4.1 × 5.8 |
US Letter, Legal, and Tabloid in inches
North America uses its own ANSI and US conventions rather than ISO 216. US Letter is 8.5 by 11 inches (215.9 by 279.4 mm), US Legal is 8.5 by 14 inches (215.9 by 355.6 mm), and Tabloid (also called Ledger) is 11 by 17 inches (279.4 by 431.8 mm). Because these sizes are defined in inches, their millimetre values are exact conversions rather than round numbers, which is why Letter and A4 look so close in size but never match exactly. A4 (210 × 297 mm) is a little narrower and a little taller than US Letter (215.9 × 279.4 mm), so a document formatted for one will shift its margins or clip slightly when printed on the other. Designers who send files across the Atlantic usually build a master at the international size and produce a US Letter export, or vice versa, instead of trusting that the two will swap without changes.
There are also the ANSI drawing sizes — A, B, C, D, and E — used by architects and engineers. ANSI A is 8.5 by 11 inches (the same as US Letter), ANSI B is 11 by 17 inches (Tabloid), ANSI C is 17 by 22 inches, ANSI D is 22 by 34 inches, and ANSI E is 34 by 44 inches. They use the same naming letters as the ISO A and B series but are unrelated to the metric system, which is another reason a single chart that lists both systems side by side saves so much lookup time.
How to look up a size and convert it to pixels
The Paper Sizes Chart combines a reference table with a live converter so the lookup and the pixel calculation happen in the same place. Four steps cover the whole workflow.
- Scan the reference table to find your paper size in the A series, B series, or US group, with dimensions shown in millimetres, centimetres, and inches.
- In the converter, choose a paper size from the dropdown to load its exact dimensions.
- Type the resolution you need in the DPI field (300 is standard for print, 72 for screen) to see the pixel width and height instantly.
- Read off the pixel result alongside the millimetre, centimetre, and inch values to set up your canvas or export.
Everything runs locally in your browser, so no files are uploaded and no sign-in is required. The page is interactive the moment it loads, which makes it useful for one-off checks during a design session as well as for batch planning across many sizes in one go.
Reading the table at a glance: mm, cm, and inches
Converting between the three physical units is straightforward once you fix one constant: one inch equals exactly 25.4 millimetres. From there, millimetres to inches is a division by 25.4, and millimetres to centimetres is a division by ten. The reference table in the chart shows all three units side by side for every size so you can copy whichever your workflow expects — millimetres for a print-shop quote, centimetres for a school assignment, inches for a US product spec. The same row also tells you at a glance that A4 is narrower than Letter, that A3 is exactly twice the area of A4, and that B5 sits between A4 and A5 in both dimensions.
A second useful comparison is the area of each sheet, which doubles with each step up the A series. A4 is one sixteenth of a square metre, A3 is one eighth, A2 is one quarter, A1 is one half, and A0 is one full square metre. The B series follows the same doubling rule but starts from a slightly larger B0 at 1000 by 1414 millimetres, so each B sheet is roughly 1.4 times the area of the corresponding A sheet. Knowing the area helps when you are estimating ink coverage, paper weight, or postage, all of which scale with the sheet area rather than its longer side.
Choosing a DPI for screen, web, or print
Pixels are different from physical units because a sheet has no fixed pixel count until you pick a resolution. DPI (dots per inch) bridges the physical and digital worlds: the pixel width equals the width in inches multiplied by the DPI, rounded to a whole pixel. At 300 DPI, the standard for high-quality print, A4 becomes 2480 by 3508 pixels; at 72 DPI, a classic screen value, the same A4 is only 595 by 842 pixels. That gap is why designers set canvas sizes in pixels but think in paper sizes, and why a print shop asks for 300 DPI artwork.
A rough rule of thumb: 72 DPI suits on-screen previews and legacy web defaults, 150 DPI is fine for office laser printers and everyday documents, and 300 DPI is the floor for any image that will be commercially printed. Photos for large-format posters often go to 600 DPI at the final export size because the viewing distance is short. Higher DPIs are wasted on screen work, where the display cannot resolve more than about 100 to 150 pixels per inch anyway. Setting the right DPI is the difference between a sharp print and a fuzzy one, and it is the single number that turns a paper size into a usable canvas.
Worked example: A4 at 300 DPI
Suppose you need the pixel canvas size for an A4 print at 300 DPI. Start with the A4 width of 210 millimetres. Divide by 25.4 to get inches: 210 / 25.4 = 8.268 inches. Multiply by 300 DPI: 8.268 × 300 = 2480.4 pixels, which rounds to 2480 pixels. The height follows the same pattern: 297 mm / 25.4 = 11.693 inches, multiplied by 300 = 3507.9 pixels, which rounds to 3508 pixels. The result, A4 at 300 DPI, is 2480 × 3508 pixels — the exact figure the chart returns. The same A4 at 72 DPI works out to 595 × 842 pixels, and at 150 DPI to 1240 × 1754 pixels, all following the same formula of inches times DPI rounded to the nearest whole pixel. For any other size, plug the millimetre dimensions into the same arithmetic, or just type the size and DPI into the converter.
Common uses for a paper size chart
Designers use a chart like this to set up documents, size images for printing, prepare files for cutting or binding, and sanity-check export dimensions before sending anything to a printer. Print buyers cross-reference a quote sheet that lists paper in inches against a design file measured in millimetres. Students often need a quick A4-to-pixels lookup for a poster assignment or a slide deck, while developers use the same chart to generate fixed-size thumbnails or PDF templates without re-deriving the maths. A single source that lists every standard size in three units and adds an instant pixel conversion removes a surprising amount of friction from each of those workflows.
If you regularly work with PDF files at specific paper sizes, the same reference pairs well with tools that need a starting canvas dimension. For instance, a chart like this can give you the exact millimetre value you need to create a blank PDF at any page size in your browser, since blank-page generators usually ask for width and height in points or millimetres rather than in pixels. Once you know the size, the rest of the workflow — exporting, merging, or splitting — becomes a matter of matching the units to the tool, which is exactly what the chart is for.