How to Show All Possible Screen Resolutions for a Display in Mac OS X

Though it’s generally recommended to use the ‘Default for display’ screen resolution option, Mac users who connect their computer to an external display or TV may find it helpful to be able to see, access, and use all possible display resolutions for a particular screen. This can be particularly useful if a display is either showing at an incorrect screen resolution, or if you’d like to use a specific resolution that is not shown in the available ‘Scaled’ resolutions list of OS X.

Reveal All Possible Screen Resolutions for a Display Connected to a Mac

This works to reveal additional screen resolution choices for any display connected to a modern Mac, it also applies to all modern versions of OS X:

1. Open System Preferences from the  Apple menu in OS X
2. Click on “Display”
3. Under the ‘Display’ tab, hold down the OPTION / ALT key while you press on the ‘Scaled’ button alongside Resolution to reveal all available screen resolution options for the display
4. Choose the resolution desired from the complete list of available screen resolutions, then close out of System Preferences as usual

You must hold the Option key when clicking on ‘Scaled’ to reveal all possible screen resolutions for the external display(s), and if you have multiple external displays in use on a Mac, you’ll want to hold the option key when choosing “Scaled” and selecting a resolution for each connected display.

For example, here’s the default selection of “Scaled” resolutions shown on a particularly 24″ external display connected to a MacBook Pro:

Now after holding down the OPTION key while clicking on the “Scaled” radio button, many additional screen resolutions are revealed as available to use:

Though these additional choices become available, they may not necessarily look right, and they may not render correctly, so just because they’re shown as options does not necessarily indicate you should use them for that particular screen.

Note this does not apply to Retina displays, where changing the resolution is a bit different and is only offered in scaled views rather than numerical resolutions anyway.

As mentioned above, sometimes this trick can be necessary to be able to select the proper screen resolution for an external display, which, although it’s pretty rare, can present itself as an improperly set screen resolution, usually at a lower resolution than what the display can handle. If you encounter that problem, sometimes simply using the Detect Displays feature after disconnecting and reconnecting the screen to the Mac can be sufficient to have the external display find and use the proper screen resolution.

Topmost photo of dual screen configuration borrowed from this Mac setup post