Show file extensions like .pdf and .docx on your Mac

Why it happens

Finder hides the end of most file names to keep them short, so report.pdf shows as just report. That makes it hard to tell a picture from a document with the same name. Ticking one box makes Finder show them all.

How to fix it

1. Click the Finder icon in the Dock so the word Finder appears next to the Apple menu at the top of the screen.

2. Choose Finder, then Settings…, click the Advanced tab and tick Show all filename extensions.

   Finder›Settings…›Advanced›Show all filename extensions

3. Close the settings window and look at any folder. Names now end in .pdf, .docx, .jpg and so on.

Still not fixed?

1. Want to hide the ending on just one file instead? Untick Show all filename extensions first, because it overrides the per-file setting. Then select the file, press Command-I, open Name & Extension and tick Hide extension.

   Finder›File›Get Info›Name & Extension

2. Getting a warning every time you change an ending? That's Finder checking you meant it. To stop it, untick Show warning before changing an extension in the same Advanced tab.

   Finder›Settings…›Advanced›Show warning before changing an extension

3. Remember that changing the ending doesn't convert the file. Renaming photo.heic to photo.jpg won't make it a JPEG, so use Export in Preview for that.

4. If Finder forgets the checkbox every time you restart, contact Apple Support so they can look at your user account.