I’ve wanted to do this at least a hundred times before, and finally looked it up. Sometimes you have connected your computer to a network many times in the past and magically your computer remembers it. But then you get a new phone and you want to connect your phone to that network, but you don’t remember the password, even though your computer is connected to it.
Certainly if your computer knows and remembers the password, it can show you what it is, right? Yep. Here’s how.
Open the Keychain Access app, found in
/Applications/Utilities/Keychain Access. Click on “System” on the left hand side in the “Keychains” section.
Sort the list by “kind”, and you will see the wireless networks that your computer has remembered. You can also use the search box in the upper right corner to type in the network name. Additionally, depending on your version of Mac OS, you might click on “Login” in the “Keychains” section, and the screenshots might look slightly different.
Double click on the network you want, and a window will pop up with its details. Then click on “Show Password”, type in your system password (not the network password) to edit your keychain, and voila, there is the password.