To print a document on paper that isn’t listed, create a custom size from the Mac print dialog, then select it for the job. Open the document and choose File > Print, open Paper Size, and choose Manage Custom Sizes. Add a size, enter its dimensions, and select it in the print dialog before printing. The available controls can vary by app and printer, so confirm the printer supports the sheet you plan to load. Apple’s guide to custom paper sizes

Create a custom size in the print dialog

First check the Paper Size menu for the size you need. If it is missing, use the custom-size controls when available:

  1. Open the document in the app you intend to print from, then choose File > Print.
  2. Open the Paper Size pop-up menu and choose Manage Custom Sizes.
  3. Click the Add button to create a size.
  4. Give the new size a recognizable name and enter its width and height using the units shown in the dialog.
  5. Set the margins if the dialog provides margin controls, then close the custom-size window.
  6. Back in the print dialog, choose the new size from Paper Size. Check the preview and other available print settings, then print.

Apple documents these controls but notes that they may not be available in every app or for every printer. If the menu or option is missing, consult the app’s or printer’s documentation; the interface may differ from Apple’s general steps. Apple Support: Print on unusual sized paper by creating a custom paper size on Mac

Enter dimensions and margins carefully

Use the actual sheet dimensions, with width and height oriented to the way you want the page laid out. For example, for a card measuring 5 by 7 inches, enter 5 inches for width and 7 inches for height for a portrait layout; swap them for landscape. This is an illustrative example, so check the units displayed in your dialog and the dimensions of your physical paper before printing.

Margins define where content can be placed on the page, but the printer may have areas it cannot print to. Keep margins within the printer’s supported printable area when that information is available. If text is clipped or margins come out incorrectly, Apple suggests trying Margins > User Defined and entering zero for nonprintable margins; it says this can help in some cases. A zero setting does not make every printer capable of printing edge to edge, so use the printer’s own documentation for its limits. Apple’s custom paper-size instructions

Choose the size for this job, not just the document

Creating a size and selecting it for the current print job are separate actions. After defining the size, choose it again from Paper Size in the print dialog. If the document itself must be laid out at those dimensions, set the page size in the app as well when it offers that control. Apple notes that apps such as Pages and Microsoft Word can set a document’s page size independently, and that print settings include scaling options. Apple Support: Choose a paper size for your printed document on Mac

If you need to print a document designed for one size onto a different sheet, use the print dialog’s scaling controls when available. Apple describes Paper Handling > Scale to fit paper size and a destination paper size option; Scale Down Only keeps smaller documents at their original size. Scaling changes how the page fits the sheet, while choosing a custom paper size specifies the sheet size. Check the preview so you can catch unexpected shrinking, clipping, or orientation changes before sending the job. Apple Support: Choose print options before you print on Mac

If the custom size is missing or the printout is wrong

If Manage Custom Sizes is absent, or the new size does not appear in the selection menu, try the same task in another app that offers the control, or consult your printer and app documentation. Apple cautions that features can vary by app and printer. Paper handling options such as tray selection or manually feeding envelopes are also printer dependent, so make sure the printer is loaded appropriately and set any available media or feed options in the print dialog. Apple Support: Choose print options before you print on Mac

For a one-off job, select the custom size in that job’s print dialog. The Default paper size setting in Apple menu > System Settings > Printers & Scanners is intended for routine printing and also affects the page size of new documents; Apple says changing it does not resize existing documents. Avoid changing the default when you only need a single unusual print. Apple Support: Choose a paper size for your printed document on Mac

Before printing a stack, review the document dimensions, selected paper size, orientation, margins, scaling, and printer feed settings. A quick single-page check can reveal a mismatch between the page setup and the paper loaded in the printer.

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