Can I run a virtual screen at 120 Hz?

You can add a 120 Hz mode to a virtual screen, while a mirrored or streamed image may still deliver fewer than 120 distinct frames per second. The advertised virtual rate and the image actually presented on the physical monitor are separate parts of the display path.

Open Settings > Displays > [virtual screen], enable Custom refresh rate list, and use Add Refresh Rate to enter 120. This configuration requires Pro. Keep a 60 Hz entry as a fallback, apply the requested virtual-screen reconnect, then select the intended resolution and refresh rate in the app menu. Reconnecting temporarily removes that virtual desktop.

The default list supplies 60 Hz modes. Custom entries can range from 24 to 240 Hz, but macOS and the Mac's virtual-display support determine which modes work. The physical monitor and its connection must also support the desired output rate. Changing the virtual list does not upgrade that connection.

If motion stutters, frames repeat or the picture develops artifacts, compare 60 Hz at the same desktop size. A reported 120 Hz value or browser timing counter may not reflect the frames reaching the physical monitor through the mirror or stream path. Results can differ with the Mac, macOS, desktop size and presentation method.

Mirroring can also change the physical target’s refresh-rate choices, including VRR. To expose its separate mode menus, enable Settings > Menu > Allow resolution change for mirror target displays, then inspect the target’s Refresh Rate menu. This permits low-level changes and lets resolution/refresh-rate protection apply to mirror targets. The connection must already offer the desired VRR mode. Check the resulting physical mode and repeat the test after reconnecting.

See Virtual Screen refresh rates for mode configuration, and virtual-screen performance for scaling and presentation tradeoffs.