Standard paper sizes on Mac include the international A series and the North American Letter, Legal, and Tabloid formats, and the everyday A4 sheet at 210 by 297 mm alongside US Letter at 8.5 by 11 inches (215.9 by 279.4 mm) sits at the top of every print dialog. macOS exposes these sizes as named presets inside File > Page Setup and inside the Paper Size pop-up menu in the print sheet, so the operating system already knows the dimensions for almost every home and office job. The built-in presets give you the name and a small preview, not the exact figure you need when you are sizing a Photoshop canvas at 300 DPI or building a new Pages document from scratch in millimetres. A reference table fills that gap, and the Paper Sizes Chart pairs every standard sheet with a live DPI-to-pixel converter that moves you from the size in the tray to the canvas on screen without a calculator. The rest of this guide covers every standard sheet a Mac recognises, the steps to look one up, how to set the size inside macOS apps and the print dialog, and how to convert any of those sizes into pixels for design work at print or screen resolution.
Paper Sizes macOS Recognises Out of the Box
The standard list that ships with the system print dialog covers the everyday ISO A series, the smaller ISO B series used for posters and envelopes, and the North American Letter, Executive, Legal, and Tabloid formats. The most common entries you will see in the Paper Size menu on a typical Mac are A3, A4, A5, B4, B5, US Letter, US Legal, Tabloid (sometimes called Ledger), and the envelope sizes DL, C5, and #10. macOS pulls this list from the printer driver installed for the active printer, which means the exact set can grow or shrink depending on which printer is selected at the top of the print sheet.
For day-to-day office work, A4 and US Letter carry almost everything: school reports, contracts, invoices, slides printed as handouts, and standard letters. A3 and Tabloid are the next step up for posters, architectural drawings, and folded brochures. A5 is the diary-and-flyer size, sitting at 148 by 210 mm. Envelope presets appear under the Paper Size menu when the printer driver supports them, and DL (220 by 110 mm) is the standard European envelope that fits an A4 sheet folded into thirds. Knowing which preset to pick matters because macOS automatically scales or crops the document to fit the chosen sheet when you print, and a wrong choice is the most common reason a layout that looks fine on screen ends up clipped at the printer.
How to Find a Paper Size in the Chart and Converter
- Scan the reference table inside the chart to find your sheet in the A series, B series, or US group, with its dimensions listed side by side in millimetres, centimetres, and inches.
- Open the converter section and pick the same paper size from the dropdown so the exact width and height load into the form.
- Type the resolution you need into the DPI field. Use 300 for print, 150 for draft proofs, and 72 for screen-only work.
- Read the pixel width and pixel height from the result panel, then copy the millimetre, centimetre, or inch value next to it depending on which unit your Mac app expects.
For example, choosing A4 from the dropdown loads 210 by 297 mm, 21.0 by 29.7 cm, and 8.27 by 11.69 in. Typing 300 into the DPI field returns 2480 by 3508 pixels, the standard print-ready size for an A4 page. Switching the DPI to 72 returns 595 by 842 pixels, which is the screen-only size you would use for a presentation slide that never goes to paper. The three unit columns let you grab whichever number your app needs without converting by hand. Designers, print buyers, students, and developers lean on this combination of reference table and live converter because it cuts the lookup, the unit math, and the pixel math into one step.
How to Set a Paper Size on Mac in Pages, Word, and the Print Dialog
macOS keeps paper size in two layers: the document layer, which controls the page size inside the app, and the print layer, which controls what the printer driver actually receives. The two usually match, but you can decouple them temporarily if you want to scale a document onto a different sheet for a one-off print. Here is how to handle each layer on a Mac.
Set the document page size
- In Pages, Word, Numbers, or Keynote, open the document and choose File > Page Setup (or in Word, Format > Document).
- Click the Page Size pop-up menu and pick A4, US Letter, A3, or another preset. The custom option lets you enter exact millimetres or inches when no preset matches.
- Tick the box labelled Use the default printer's paper size if you want the document to follow the active printer. Leave it unticked if the page size should stay locked regardless of which printer receives the job.
- Click OK to apply. The rulers and margins inside the app snap to the new sheet.
Set the paper size for a single print job
- Open File > Print in any app. The print sheet slides down from the top of the window.
- Find the Paper Size pop-up menu inside the print sheet. On a typical install it sits directly under Orientation.
- Pick the preset that matches the sheet loaded in the printer tray. If you do not see the size you need, choose Manage Custom Sizes and type the exact dimensions in millimetres or inches.
- Adjust the Scale slider if you want to shrink or grow the document to fit a sheet that is not its native size.
Set a permanent default for every print job
- Open the Apple menu and choose System Settings (System Preferences on older macOS releases).
- Click Printers & Scanners in the sidebar, then select the default printer.
- Open the Default Paper Size menu and pick the size that matches the paper you load most often.
- Close the window. From this point on, every app that asks the system for the default paper size receives this value until you change it again.
Confirm the size sent to the printer
- Reopen File > Print, then click Show Details at the bottom of the print sheet.
- Open the Advanced or Paper Handling panel, depending on the driver. The actual size the printer is about to receive is listed there in both inches and millimetres.
- If the listed size does not match what you set, return to the Paper Size menu and pick again. A mismatch here is what causes macOS to silently scale the job or print onto the wrong sheet.
Converting a Paper Size to Pixels for Design Work on Mac
When you create a new document in Photoshop, Affinity Designer, Pixelmator, or any canvas-based Mac app, the page size is asked for in pixels rather than millimetres. The conversion is the same regardless of which app you use: take the width and height in inches, multiply each by the DPI, and that is the pixel count for that side of the canvas. The formula in full is pixels = (mm / 25.4) x DPI, because one inch equals exactly 25.4 millimetres.
Worked example with A4 at 300 DPI:
- Width in inches: 210 mm / 25.4 = 8.27 in.
- Pixel width: 8.27 x 300 = 2480 pixels (rounded to the nearest whole pixel).
- Height in inches: 297 mm / 25.4 = 11.69 in.
- Pixel height: 11.69 x 300 = 3508 pixels.
The result is a 2480 by 3508 pixel canvas, which is the standard print-ready size for an A4 page. Drop the DPI to 72 and the same A4 sheet becomes 595 by 842 pixels, the classic on-screen size used by older Office documents and most web previews. At 150 DPI, the in-between choice for draft proofs and high-quality on-screen review, the canvas lands at 1240 by 1754 pixels. The companion guide Paper Size Chart With Image: Pixels at Any DPI walks through the same conversion for the larger A and B series sheets when you are sizing posters and book spreads.
A Series, B Series, and US Sizes Compared
The international A series is built around ISO 216, which sets every sheet to the same height-to-width ratio of the square root of two (about 1.414). That ratio is what lets you fold an A sheet in half across its longer side and land on the next size down with the same proportions. The series is anchored by A0 at 841 by 1189 mm, which has an area of one square metre, and ends at A10. The B series (B0 at 1000 by 1414 mm, then B1, B2, and so on) sits between the A sizes and is used for posters, books, and envelopes when an in-between dimension is needed. North America uses ANSI and US conventions instead, defined in inches, which is why US sizes do not round to whole millimetres.
| Size | Millimetres | Centimetres | Inches |
|---|---|---|---|
| A4 | 210 x 297 mm | 21.0 x 29.7 cm | 8.27 x 11.69 in |
| A3 | 297 x 420 mm | 29.7 x 42.0 cm | 11.69 x 16.54 in |
| A5 | 148 x 210 mm | 14.8 x 21.0 cm | 5.83 x 8.27 in |
| B5 | 176 x 250 mm | 17.6 x 25.0 cm | 6.93 x 9.84 in |
| US Letter | 215.9 x 279.4 mm | 21.59 x 27.94 cm | 8.5 x 11 in |
| US Legal | 215.9 x 355.6 mm | 21.59 x 35.56 cm | 8.5 x 14 in |
| Tabloid / Ledger | 279.4 x 431.8 mm | 27.94 x 43.18 cm | 11 x 17 in |
The crucial detail in the table is that A4 and US Letter are close but never equal: A4 is 5.9 mm narrower and 17.6 mm taller. A document set up for A4 and printed onto Letter, or the other way around, usually shifts its margins and may clip a header or footer. The companion guide Paper Sizes Explained: A Series, B Series, and US Formats covers the full A and B ranges, including the envelope sizes that match each sheet.
Common Paper Size Mix-Ups Mac Users Run Into
Three mistakes account for most of the paper-size headaches Mac users report. The first is the Letter-versus-A4 swap, which is invisible on screen because the two sheets are nearly the same size, but shows up as clipped or shifted content at the printer. The second is leaving the default at US Letter after installing a new printer in a country that uses A4, which causes macOS to silently scale every job and produce slightly fuzzy output. The third is feeding envelopes through a printer without picking an envelope preset, which most drivers handle poorly and which often prints straight onto the platen instead of the envelope.
A quick habit avoids all of them. Open the chart before you set up a new document or a new print job, confirm the exact millimetre or inch value, then pick the matching preset in macOS. If your workflow mixes ISO and US sizes, save two custom sizes in Manage Custom Sizes so the exact dimensions are one click away rather than something you have to remember. That single habit is what keeps documents, canvases, and print jobs aligned across the operating system and any printer you attach to the Mac.