Can I split one physical monitor into two independent desktops?

There is no simple BetterDisplay setting that turns two regions of a physical monitor into two independent hardware displays. You can show separate virtual desktops in Picture in Picture windows, but the physical monitor’s original desktop remains underneath them.

For a software workaround, create two virtual screens with the desired desktop sizes, open each in Picture in Picture, and position the viewing windows in the two regions. For example, two 1920 × 1080 desktops have the proportions of two stacked halves of a 1920 × 2160 portrait monitor. Picture in Picture requires Pro and screen-capture permission.

Follow the two-desktop tutorial for independent source creation, logical and pixel sizing, window placement, pointer handling and safe removal, with an ultrawide example and a stacked portrait variant.

For a clean presentation, choose Above Menu, Dock, Spaces for each PIP window and turn off Title Bar & Window Controls and Window Shadow. Position and resize the windows to cover the intended regions. These options change the viewing windows. They do not remove the physical desktop underneath. See Picture in Picture for the window settings.

Move the apps you want to use onto the virtual desktops, and select those desktops in your screen-sharing app. Each virtual desktop can provide a separately selectable sharing source when the sharing app supports it. Placing two viewing windows on the physical monitor does not make an app running on that physical desktop use only half of it in fullscreen.

This setup needs deliberate window placement and pointer handling. BetterDisplay saves each PIP window’s size and position. Once you have placed the windows, you can enable Lock Window Position and Prohibit Resizing to avoid moving or resizing them accidentally. Enable Start Automatically if you want them to reopen when their source screens connect.

Test startup and sleep/wake with your arrangement, especially if the physical displays change. The virtual screens remain additional displays in macOS, and the viewing windows are not automatically independent input surfaces. See working with virtual desktops and moving the pointer to the source desktop.

If your monitor supports hardware Picture by Picture, that may be a better fit for separate display inputs. Check that it supports the particular split you need: side-by-side support does not establish a vertically stacked layout. See hardware Picture by Picture for resolution considerations.

Open each PIP window from the menu of the virtual screen you want to view, then move that window onto the physical monitor. Capturing the physical monitor that contains the viewing window instead can produce a repeating image of the window inside itself. For two equal stacked halves of a portrait 9:16 screen, each virtual desktop should have a 9:8 aspect ratio.