Paper sizes on iPhone are the standardized dimensions you see in the iOS Print sheet - names like A4, US Letter, 4x6, and Legal - plus the pixel dimensions those physical sheets translate to once you pick a resolution. AirPrint exposes both the ISO A and B series and the North American sizes, so the same Print menu lets you target any standard sheet your printer can hold. The iPhone, however, does not show millimetres, centimetres, or pixels next to those names; the Print menu is limited to size labels. To get the underlying numbers - useful when you are exporting a PDF on the phone, designing an image for print, or sanity-checking artwork - you need a reference chart that lists every standard size in mm, cm, and inches, then a converter that turns any of those sizes into pixels at the DPI you plan to print or display at. The Paper Sizes Chart runs in any browser tab on the iPhone, pairs a complete reference table with a live DPI-to-pixels converter, and works without installing an app or signing in.
Where iPhone Shows Paper Sizes
The iPhone exposes paper sizes in two distinct places: the operating system's Print sheet, and any PDF or image tool that lets you set a page size before export. The Print sheet is the one most people meet first. Tap the Share button in Mail, Safari, Photos, or Notes, choose Print, then tap the page-style menu in the top-right of the print preview. On recent versions of iOS that menu lists Letter, Legal, A4, A5, A6, B5, 4x6, 5x7, and a few photo-specific sizes such as postcard. The exact list varies slightly by printer model and by region, but the international ISO A and B sizes always appear alongside the US sizes because AirPrint drivers surface both.
Outside of printing, paper sizes matter when you create a PDF on the iPhone. Apps such as Files, Pages, and most note-taking apps let you start a new document from a template; the templates are named after paper sizes - A4, US Letter, A5 - so the page you type on is already the right size for printing later. The moment you want to export a custom-sized image or PDF, however, the app usually only asks for width and height in pixels, not in inches or millimetres. That gap is where a converter earns its place.
Standard Paper Sizes at a Glance
The table below shows the dimensions iPhone users most often see in the Print menu, in millimetres, centimetres, and inches. All values come from published standards - ISO 216 for the A and B series, and ANSI or US standards for Letter, Legal, and Tabloid - so the numbers are exact, not rounded. Pixel values are deliberately omitted because they change with DPI; the converter at the Paper Sizes Chart gives you the live pixel figure the moment you choose a resolution.
| Paper size | Millimetres (mm) | Centimetres (cm) | Inches |
|---|---|---|---|
| A4 | 210 x 297 | 21.0 x 29.7 | 8.27 x 11.69 |
| A5 | 148 x 210 | 14.8 x 21.0 | 5.83 x 8.27 |
| A6 | 105 x 148 | 10.5 x 14.8 | 4.13 x 5.83 |
| B5 | 176 x 250 | 17.6 x 25.0 | 6.93 x 9.84 |
| US Letter | 215.9 x 279.4 | 21.59 x 27.94 | 8.5 x 11 |
| US Legal | 215.9 x 355.6 | 21.59 x 35.56 | 8.5 x 14 |
| Tabloid (Ledger) | 279.4 x 431.8 | 27.94 x 43.18 | 11 x 17 |
| 4 x 6 photo | 101.6 x 152.4 | 10.16 x 15.24 | 4 x 6 |
| 5 x 7 photo | 127.0 x 177.8 | 12.7 x 17.78 | 5 x 7 |
The ISO 216 system is anchored by A0, which has an area of almost exactly one square metre and measures 841 by 1189 mm. Each size down the ladder - A1, A2, A3, A4 - is the previous sheet folded in half across its longer side, which is why every sheet in the series keeps the same height-to-width ratio of the square root of two (about 1.414). A4 lands four folds below A0 at 210 by 297 mm. The B series sits between the A sizes and is used for posters and envelopes; B5 at 176 by 250 mm is a common book-paper size that fits between A4 and A5.
The North American sizes are defined in inches first, then converted to millimetres using the exact factor 1 inch equals 25.4 mm. That is why US Letter at 215.9 by 279.4 mm never lands on a round number - and why A4 and Letter are close but never identical. A4 is slightly narrower and a little taller, so a document designed for one can clip or shift margins when printed on the other.
How to Look Up a Paper Size and Convert to Pixels on iPhone
Follow these steps to find a paper size and its pixel dimensions right on the iPhone, using the Paper Sizes Chart in Safari or any other browser.
- Open Safari on your iPhone and load the Paper Sizes Chart page. The chart loads fully in the browser, so you do not need to install an app or sign in.
- Scan the reference table to find your paper size in the A series, B series, or US group. Each row shows the size in millimetres, centimetres, and inches side by side.
- In the converter, choose your paper size from the dropdown to load its exact dimensions into the input fields.
- Type the resolution you need in the DPI field. Use 300 for high-quality print output, 150 for draft prints, and 72 for screen-only PDFs.
- Read off the pixel result next to the millimetre, centimetre, and inch values. The pixel figure updates instantly as you change the DPI, so you can compare print and screen sizes without leaving the page.
The converter runs locally in your browser, which means no file is uploaded and no account is created. You can rotate the iPhone to landscape if the table feels tight in portrait, and you can bookmark the page for quick access the next time you print or export.
A4 in Pixels at 300 DPI: A Worked Example for iPhone Users
The pixel value that gets quoted most often is A4 at 300 DPI, because 300 DPI is the resolution print shops ask for. Here is how that figure is built, step by step, so you can repeat the same calculation for any other size.
Start with A4's width in millimetres: 210 mm. Convert to inches by dividing by 25.4, since 1 inch equals exactly 25.4 mm: 210 / 25.4 = 8.2677 inches. Multiply by the DPI to get the raw pixel width: 8.2677 x 300 = 2480.31 pixels. Round to the nearest whole pixel: 2480 pixels.
Now repeat for the height. A4 is 297 mm tall. 297 / 25.4 = 11.6929 inches. 11.6929 x 300 = 3507.87 pixels. Rounded: 3508 pixels.
So A4 at 300 DPI is 2480 by 3508 pixels, the standard canvas size for an A4 print file. The same A4 sheet at 72 DPI, a typical screen value, is only 595 by 842 pixels, because 210 / 25.4 x 72 rounds to 595 and 297 / 25.4 x 72 rounds to 842. This is why designers think in paper sizes when laying out artwork but set the canvas in pixels: the physical sheet has no fixed pixel count until you choose a resolution. The Paper Sizes Chart performs this calculation for every paper size the moment you pick a DPI, so you do not have to redo the arithmetic every time you switch from 72 to 150 to 300 DPI.
Why Pixel Size Matters When You Print or Export on iPhone
Setting the right pixel canvas is the difference between a print that looks crisp and one that looks pixelated. Printers spray tiny dots of ink, and a 300 DPI image gives the printer enough dots per inch to render smooth edges and fine type. At 72 DPI, the same image on paper shows visible squares instead of smooth curves, because each pixel must be stretched across multiple ink dots.
iPhone cameras shoot at far higher resolutions than that. Recent models capture 12-megapixel or 48-megapixel photos, which is more than enough to print at A4 or even A3 without resizing. The issue usually runs the other way: when you crop, annotate, or export a photo on the iPhone, the app may save a smaller version that is fine for screen but too small to print. Knowing that A4 at 300 DPI needs an image of 2480 by 3508 pixels lets you check the export size before sending anything to a printer. If the file is short of that, you can either shoot at a higher resolution, choose a smaller paper size, or accept a slightly lower DPI.
Two practical cases come up most often on iPhone. First, exporting a PDF from Notes, Pages, or a third-party app: the export dialog usually lets you set the page size, and picking A4 or Letter there matches what your printer expects, so the printed output fills the page instead of leaving a white border. Second, printing a photo at home: a 4 x 6 print at 300 DPI needs an image of 1200 by 1800 pixels, which any modern iPhone can supply. If you scale the photo down too aggressively before printing, the printer upsamples it and the result looks soft.
For anyone who needs the same numbers again and again - a freelance designer exporting client PDFs, a student submitting a print-ready assignment, a small-business owner printing shipping labels - keeping a quick reference open on the phone saves repeated lookups. The Paper Sizes Chart stays usable on the iPhone because it is a regular web page, not an app that needs updating, and the converter responds instantly as you switch between paper sizes and DPI values.
If you're weighing options, PDF N-Up on iPhone: 2-Up and 4-Up in Safari covers this in detail.
If you're weighing options, Create a Blank PDF on iPhone in Mobile Safari covers this in detail.