To find and resolve duplicate fonts on a Mac, open Font Book and choose File > Resolve Duplicates. For control over which copy remains active, choose Resolve Manually, review each font’s copies, select the version to keep, and resolve it. Choose automatic resolution when you’re comfortable letting Font Book handle the duplicates using your settings. (Apple’s Font Book guide)

Find duplicate fonts in Font Book

Font Book checks for duplicates when you install a font and may offer to keep both versions, skip the installation, or replace the existing font. To check fonts already installed, open Font Book and select File > Resolve Duplicates. This is Font Book’s documented manual check; Apple does not document a separate duplicate-search command in this workflow. (Apple’s Font Book guide)

If Font Book presents a choice between automatic and manual resolution, use the option that matches your goal. Automatic resolution is quicker, but the treatment of inactive copies depends on Font Book settings. Manual resolution lets you inspect copies and choose which one stays active.

Resolve duplicates manually

  1. In Font Book, choose File > Resolve Duplicates, then choose Resolve Manually.
  2. Examine the duplicate group and its copies. Font Book marks its recommended choice Active and selects it by default. Select another copy if you want a different version kept active.
  3. Click Resolve This Duplicate to handle that group. If Font Book found more than one group and you have reviewed them, click Resolve All Duplicates.
  4. Recheck the font list and, if the font is used in a document, confirm that the intended version is available in the app where you need it.

Font Book’s “Active” label is its recommendation, not a statement that the selected copy is necessarily the one you intended. Compare the copies before resolving when versions or installation sources matter. Apple documents the selection and resolution controls, but does not promise that every app will immediately reflect the change; for issues in a third-party app, Apple directs users to that app’s developer. (Apple’s Font Book guide, Apple’s troubleshooting guide)

Choose whether inactive copies go to the Trash

To set how Font Book handles inactive duplicate files when possible, open Font Book > Settings and look under General for Resolve duplicates by moving files to the Trash when possible. When this option is selected, Font Book can move inactive copies to the Trash during resolution; when it is not selected, duplicates may instead be deactivated. Check this setting before using automatic resolution if you want to know whether inactive files may be moved. (Apple’s Font Book settings guide, Apple’s Font Book guide)

Moving a copy to the Trash differs from deactivating it. A deactivated font remains on the Mac, appears dimmed in Font Book, and can be activated again. A removed font is no longer available in Font Book or in apps’ Fonts windows; Apple says removed fonts are moved to the Trash. (Apple’s font removal guide)

When duplicate resolution is unavailable

Some fonts are installed and activated automatically by macOS. System fonts cannot be removed or deactivated, and Font Book may show those controls dimmed. Do not try to force a system font out of service as a duplicate-resolution step. (Apple’s troubleshooting guide)

If a font looks wrong or a document has trouble opening, a duplicate may not be the only issue. Font Book can validate a selected font with File > Validate Selection, or validate a file with File > Validate File. In the validation window, green indicates a pass, yellow a warning, and red a failure. Apple says a failed font can be selected and removed with Remove Checked. Validation and duplicate resolution address different problems, so use validation when you suspect a damaged font. (Apple’s Font Book guide)

If the font remains missing or looks different in a particular third-party app after you resolve duplicates, check that app’s support guidance. Font Book can manage the Mac’s fonts, but Apple advises contacting the app developer for help using fonts in third-party apps. (Apple’s troubleshooting guide)

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