Connect an external display to your iMac
You can connect an external display, a projector, or an HDTV to ports on your iMac that support video output.
Connect one external display (up to 6K), a projector, or an HDTV to one of the two Thunderbolt / USB 4 ports 
on your iMac. For more information about the ports, see Take a tour: iMac.
Note: If you connect multiple devices to a single port and one of the devices is an external display, the display must be the last device in the connection. This doesn’t apply when you use a multiport adapter or hub.
Tip: If you have an HDTV connected to an Apple TV, you can use AirPlay to mirror your iMac screen in up to 1080p HD. See Stream content on a larger screen with AirPlay for details.
If your display has a connector that doesn’t match the port you want to use, you may be able to use it with an adapter (sold separately). Visit apple.com, your local Apple Store, or other resellers for more information and availability. Review the display’s documentation or check with the display’s manufacturer to make sure you choose the right product. See the Apple Support article Adapters for the Thunderbolt 4, Thunderbolt 3, or USB-C port on your Mac.
To connect this device | Use this cable or adapter |
|---|---|
Apple Pro Display XDR | Thunderbolt 3 (USB-C) cable |
Thunderbolt 3 (USB-C) display | Thunderbolt 3 (USB-C) cable |
USB-C display | USB-C (USB 3.1) cable |
Thunderbolt 2 display | Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter |
HDMI display or HDTV | USB-C to HDMI adapter or a USB-C Digital AV Multiport adapter. |
VGA display or projector | USB-C VGA Multiport adapter |
DisplayPort or Mini DisplayPort display | USB-C to DisplayPort or Mini DisplayPort adapter |
DVI display or projector | USB-C to DVI adapter |
Adjust and arrange displays. After you connect an external display or projector, use Displays settings in System Settings to set how the displays are arranged, turn screen mirroring on or off, and make other adjustments to color, resolution, and more. See Connect a display to your Mac in the macOS User Guide.
Troubleshooting. If you’re not sure how many external displays your iMac supports, check your Technical Specifications. Open System Settings, choose Help > iMac Specifications, then locate Video Support (you may need to scroll). To troubleshoot an issue with an external display, see Get help with video issues on external displays connected to your Mac.