I have a 27" iMac with 2.5K built-in display resolution. Also i may replace it with a 5K/retina one. The problem is mirroring it's display without changing my mac's resolution other than it's native resolution.

When I use a Thunderbolt to HDMI converter and an HDMI cable, my mac forces me to use lowest resolution between itself and my tv (1920x1080/2K). So it prefers the tv's resolution and my mac switches it's built-in display resolution to 2K and this is not what I want.

So, I think about Apple TV and AirPlay mirroring. My question is:

Is it possible to mirror my mac's high resolution built-in display to a low resolution (2K) tv through Apple TV without changing the mac's resolution?

If it's possible, naturally higher resolution image will be scaled down/transcoded to a lower resolution image. Texts and details on original image will be corrupted/blurred but it's ok, I don't expect/need a super clear image on the tv.

So, will Apple TV do the job, can it transcode original high resolution image to fullscreen 2K image for my tv?

  • Long time now... Have you found any solution? Looks like Apple is sitting quiet knowing they simply cannot force their hardware to mirror Retina 5K to their Apple TV, which sound ridiculous. Can't they simply scale resolution down before sending it to the Apple TV?
    – cadavre
    Nov 3, 2018 at 0:02

1 Answer 1


Well macOS comes built-in with this feature. When connecting your Mac to AirPlay, open System Preferences > Displays and just pick the Mac's resolution instead of the TV's resolution (mirror Mac display - match Mac's resolution).

On newer macOS versions you can also change this setting from the Control Center icon on the menu bar (next to the Clock) and then pick Displays.

If you want something more complex, there's an app called SwitchResX which allows you to force any resolution you'd like on your any of your monitors.

The main features are simple enough but it also allows you to change extremely advanced settings so be careful if for example you want to change the monitor timings/frequencies or something like that.


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