How to change the default PDF viewer on a Mac
In Finder, select any PDF and choose File > Get Info, or press ⌘I. Expand the Open with section, pick the app you want from the pop-up menu, then click Change All and confirm. From then on, double-clicking any PDF opens it in that app. To go back, repeat the steps and pick Preview.
With PDF Unlimited (free)
Select a PDF in Finder
Click once on any PDF in Finder, on your desktop or in Downloads. Do not open it.
Open Get Info
Choose File > Get Info, or press ⌘I. You can also Control-click the file and choose Get Info.
Expand Open with
In the Info window, click the arrow next to Open with to show the app menu.
Choose the app
Click the pop-up menu and choose the app you want, for example PDF Unlimited. If it is not listed, choose Other… and find it in Applications.
Click Change All
Click Change All, then confirm. Every PDF on your Mac now opens in that app when you double-click it.
With Preview, built into macOS
Select a PDF and press ⌘I
In Finder, select any PDF and choose File > Get Info.
Pick Preview
Under Open with, choose Preview from the pop-up menu.
Change All
Click Change All and confirm. PDFs open in Preview again.
Open a PDF in a different app just once
You do not have to change the default to try another app. Control-click the PDF in Finder, choose Open With, then pick the app. Or drag the file onto the app's icon in the Dock. The default stays as it was.
Apple's own tip is worth repeating: do not click Change All if you only want that one file to open in a different app. Without Change All, the choice applies to the selected file only.
How to open a PDF on a Mac
Double-clicking a PDF opens it in the default app, which is Preview on a new Mac. You can also open the app first and choose File > Open, or drag the file onto the app icon. If nothing happens, or you see an error, see what to do when a PDF won't open on Mac.
Why your default keeps changing
Some apps offer to become your default PDF viewer when you install or first open them, and it is easy to click yes without noticing. Web browsers can also open downloaded PDFs themselves instead of handing them to a Mac app, which is a browser setting, not a Finder one.
If PDFs suddenly start opening somewhere unexpected, run through the steps above again and click Change All. That resets the choice for every PDF.
Make PDF Unlimited the default
If you use PDFs for more than reading, it helps when they open straight into an app that can sign, merge, compress and redact. Download PDF Unlimited, drag it to Applications, then follow the steps on this page and choose it in the Open with menu.
It opens in Read mode, so a double-click still feels like a viewer: thumbnails, outline, search. Switch modes when you need to do something. Comparing options first? See the best free PDF readers for Mac.
If the app is missing from the list
The Open with menu only lists apps your Mac knows can open PDFs. If you just installed one and it is not there, open the app once from Applications, then try again. If it is still missing, choose Other… at the bottom of the menu and pick it from the Applications folder. Apps left in Downloads or on a disk image may not show up, so move them to Applications first.
Questions
How do I set the default PDF viewer on a Mac?
Select a PDF in Finder, press ⌘I, choose an app under Open with, and click Change All. Confirm when asked.
How do I make Preview my default PDF viewer again?
Follow the same steps and choose Preview in the Open with menu, then click Change All.
Why don't I see Change All?
Make sure you selected a single PDF file, not a folder or several different file types. The Open with section must be expanded.
Can I change the default without making it permanent?
Yes. Control-click the file and choose Open With to use another app just once. Your default stays the same.
Will changing the default PDF app affect my files?
No. It only changes which app opens them. The PDFs themselves are not modified.