How To Show Or Hide Filename Extensions On Your Mac

Hi, this is Gary with MacMost.com. Let me tell you why sometimes when you look at file names on your Mac they have extensions and sometimes they don't.

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So when you're looking at files in the Finder sometimes it can be confusing as to why you see file extensions for some files but you don't see them for other files. If you want to see them for all files it's easy to turn on a single preference in the Finder and then you see all file extensions. But if you have that turned off then you get a mix. Why is that? What causes some files to show extensions while other don't. 

So here I have some files in the Finder and I can see that some of them show a file extension and others do not. Here's one with a .rtf file extension and here's one that has no file extension at all. If I want to force the Finder to show file extensions for every file that has one I can do that by going to Finder, Preferences, then go to Advanced, and then turn on Show all filename extensions. If I do that you can see every single file here has the extensions shown. If I turn it off some of them will hide the file extension but others do not. What's the difference?

Let's take a look at the information for these files. With the first file selected I'm going to choose File, Get Info or Command i. It will show me, for this file, that the filename and extension does indeed include the extension there but Hide extension is turned off. It's an option here under Name & Extension. If you don't see it you may have to open up the Name & Extension section. If I turn on Hide extension you can see the extension is now hidden.

Now, sure enough, if I were to select a file that has no extension and do Command i, for get info, you can see here that Hide extension is indeed checked. That's why the extension is hidden. So I can turn that off if I want to show the extension for that particular file. Turn it On if I don't want to show the extension. So every file has this checkbox and can either show or hide its own extension.

Now if I want to change it for several files I can. I could select several files and instead of doing Command i for to get info I'm going to hold the Option key down and choose Show Inspector. Show Inspector not only creates a persistent window that will show me information for whatever is selected, but if I have more than one item selected it will simply say 2 Items up here and still allow me to make changes across those items like, for instance, the Hide extension checkbox. I can turn it Off for both of those at the same time or On for both of those at the same time.

Now what could be a little confusing is why do some files have those turned off and others have those turned on. For instance here's a Numbers document. If look at that one I could see the Hide extension is turned on. Here's another Numbers document and if I look at that one I could see that Hide extension is turned off. Why were these created differently? Well it's pretty simple.

When you create a new file it simply follows the preference in Finder Preferences Advanced as to whether this checkbox is checked here. So right now I have it turned off.  So if I go to create a new file in, say, Pages and let's say  it's called Test 3 and I will Save it as Test 3. You could see Test 3 has the file extension. That checkbox is turn Off which matches the Finder Preference right here turned Off. If I now turn it On and I create a new document in Pages and call that one Test 4 and Save it. Now if I look at the info for this document here you could see that's checked and that matches the Finder Preference right here. So I could uncheck this now and notice how Test 4 has no file extension and Test 3 has a file extension because it's following the setting I had in the Finder when I created the file.

That's how people end up with a mix of some files with the file extension being shown and others with it not. If I didn't want to use file extension in most cases it's pretty easy for me to select everything to Command Option i. Turn this On for all of them and you could see it's On. Now I'll have no file extensions except when I go to Finder Preferences and turn this On.

So what's the right way to go. Well if you always want to see file extensions, like I do, then you just have that setting turned On in the Finder and don't worry about it. You'll always see extensions. If, on the other hand, you'd rather not see them just have it always turned Off. If you want to see them temporarily then turn that Preference On in the Finder but remember to turn it Off right away afterwards. Otherwise you're going to get end up turning on File Extensions for any new documents you create. It's easy to correct the problem if you accidentally turned it on for a few. Just use the Inspector or Get Info for that file and turn it off.