How to Change the Default Paper Size in macOS (A4 vs US Letter)

When sending documents to a printer or exporting digital PDFs from native Mac apps such as Pages, Safari, or Preview, macOS automatically formats your pages based on your system-wide default paper size. By default, Apple sets this parameter according to your primary regional language; if your Mac is configured with US English, macOS defaults to US Letter (8.5 × 11 inches), whereas British English and European regions default to international standard A4 (210 × 297 mm).

When this default does not match your physical printer paper tray, print jobs can fail, prompt constant manual bypass tray errors, or cause printed documents to truncate text and scale margins awkwardly. Configuring the correct default paper size eliminates these issues across all installed printers and applications.

Understanding the Difference Between A4 and US Letter

While A4 and US Letter appear superficially similar, their physical aspect ratios and dimensions diverge significantly:

• A4 (ISO 216): Measures 210 × 297 mm (8.27 × 11.69 inches). It is narrower and noticeably taller than US Letter. Standardised across the United Kingdom, Europe, Australia, India, and most global territories.
• US Letter (ANSI A): Measures 215.9 × 279.4 mm (8.5 × 11.0 inches). It is slightly wider and shorter than A4. Standardised primarily across North America (United States, Canada, and parts of Mexico).

If you attempt to print a US Letter layout onto an A4 sheet without scaling, the bottom 17.6 millimetres of margin space remains excessively large, while top and side margins may sit uncomfortably close to the sheet edge.

How to Change the Default Paper Size in macOS Sonoma and Sequoia

To configure your global default paper standard across modern macOS versions:

1. Click the Apple menu () in the top-left corner of your menu bar.
2. Select System Settings.
3. In the left-hand navigation sidebar, scroll down and click Printers & Scanners.
4. On the right side of the window, locate the Default paper size dropdown menu situated at the bottom of the pane.
5. Click the dropdown and select your preferred standard:
   • A4 (for international standard office printing)
   • US Letter (for North American documentation)

The selection applies immediately. Every native and third-party application will now pre-populate new document canvases and print preview dialogue sheets with your chosen format.

Adjusting Paper Size in macOS Ventura and Monterey

If you are using an older version of macOS featuring the legacy System Preferences panel:

1. Open System Preferences from the Apple menu.
2. Click Printers & Scanners.
3. Locate the Default paper size dropdown at the bottom of the primary printer list.
4. Select either A4 or US Letter.

Overriding Paper Size for Individual Print Jobs

Setting a system default does not prevent you from printing foreign document formats when needed. Whenever you trigger a print job (via Command + P in any Mac application):

1. In the Print dialogue sheet, click Show Details if the full settings panel is collapsed.
2. Click the Paper Size dropdown.
3. Select the alternative format required for that specific job (such as Legal, Executive, A5, or #10 Envelope).
4. Click Print. macOS will remember the custom choice solely for that active application session without altering your global system default.