How to snap windows into layouts on a Mac

Before you start

Install Casement and allow Accessibility (see set up Casement). Snap layouts are free.

If macOS tiling is enabled, it may also react when you drag to an edge. Turn off one so only one acts.

Steps

1. Open the windows you want to arrange.
2. Click and hold the title bar of the first window, and drag it toward the top of the screen.
3. A set of layouts appears: halves, thirds, one large window with two stacked beside it and a four-way grid. Move over the one you want and release.
4. Repeat with the next window and choose its zone; the layout fills in around them.
5. To use the keyboard instead, press ⌃⌥← or ⌃⌥→ for left and right halves, ⌃⌥↑ to fill the screen, or ⌃⌥2, ⌃⌥3 and ⌃⌥4 to tile the front two, three or four windows.
6. On a larger external monitor, try the four-column layout or ⌃⌥6 for a six-window grid.

Check that it worked

The window should fill its zone exactly, with no gaps beyond the usual margin.

Repeat on a second monitor; layouts apply to whichever screen you drag to.

If something goes wrong

• Nothing appears when you drag. Check Accessibility is on for Casement.
• The window jumps somewhere unexpected. macOS tiling may also be active; turn one off.
• A shortcut does nothing. Another app may use the same keys. Change either shortcut.

What to do next

Browse the keyboard shortcuts, and the guides on Windows-style snap layouts and snapping on an ultrawide monitor.

Layouts worth learning first

• Halves. Two windows side by side, such as a document and its reference. This is the layout most people use fifty times a day.
• Thirds. Three columns on a wide screen: a main window flanked by chat and mail.
• One large, two stacked. A main window with two smaller ones beside it, good for watching a dashboard while you work.
• Four-way grid. Four windows on a big screen for monitoring or comparison.

Pick two arrangements and use only those for a week. Muscle memory builds faster when the choice is small.

A worked example

Sam works on a 34-inch ultrawide. He used to keep one window maximised and hunt for the others. Now he snaps a code editor to the left two-thirds, a browser to the right third, and moves chat to the laptop screen. The arrangement is the same every morning, so he stops thinking about windows and thinks about the work. When he needs focus, ⌃⌥↑ fills the screen with the editor, and ⌃⌥← puts it back.