The short version: Install Rectangle, grant it Accessibility permission, then hit Ctrl + Option + ← to snap the active window to the left half and Ctrl + Option + → for the right. That’s split screen in two keystrokes, and unlike macOS Split View it won’t hide your desktop or disrupt Cmd+Tab. Full setup and shortcut list below.
The fastest path to split screen
Want the answer without the context? Download the Rectangle app, allow it under System Settings → Privacy & Security → Accessibility, then use these two:
Left half — Ctrl + Option + ←
Right half — Ctrl + Option + →
Click the window you want to move, press the shortcut, then click the other window and press the opposite one. Two windows side by side in roughly four seconds. Everything below walks the setup properly and covers the rest of the shortcuts worth knowing.
Why not just use macOS Split View?
macOS has shipped Split View for years — hold the green button, pick a side. It functions, but it carries a cost that catches people out: Split View shoves both windows into a full-screen space of their own. Your desktop vanishes, other windows get harder to reach, and Cmd+Tab behaves differently because you’ve left the normal desktop behind.
Sequoia’s newer tiling improved matters and handles basic halves without going full-screen, which is a real gain for casual use. It still has no size cycling, no sixths, no custom shortcuts. A dedicated app keeps windows on your regular desktop, snaps them instantly by keyboard, and lets you keep working the way you already do. That’s the difference people clock within a day.
Step-by-step setup
Step 1 — Install Rectangle
Grab Rectangle from the official site, or via Homebrew: brew install --cask rectangle. It’s free and open source, so there’s nothing to buy and no account to make.
Step 2 — Grant Accessibility permission
First launch triggers an Accessibility request. macOS opens System Settings → Privacy & Security → Accessibility, where you flip Rectangle on. This is mandatory — macOS blocks any app from moving windows without it, and every window manager needs the same thing. If snapping misbehaves later, check this toggle first.
Step 3 — Snap your first two windows
Click the window you want on the left, press Ctrl + Option + ←. Click the second window, press Ctrl + Option + →. That’s your split screen, with both windows still on the normal desktop where Cmd+Tab works exactly as it always did.
The shortcuts worth memorizing
Two are enough to split a screen, but these are the ones that become muscle memory quickly.
Left half — Ctrl + Option + ←
Right half — Ctrl + Option + →
Maximize — Ctrl + Option + Enter
Center — Ctrl + Option + C
Top half — Ctrl + Option + ↑
Bottom half — Ctrl + Option + ↓
Next display — Ctrl + Option + Cmd + →
Previous display — Ctrl + Option + Cmd + ←
All of them remap freely in Rectangle’s settings if the defaults collide with another app or don’t suit your hands.
The trick most people miss: size cycling
This is the feature that changes how split screen feels. Press the same shortcut twice and the window cycles to a different width — Ctrl+Option+← once gives a half, again a third, again two-thirds. One combination covers several layouts, so you stop calculating which shortcut yields which width and just tap until it looks right.
It’s why a two-thirds/one-third split is as easy as a fifty-fifty. On a wide monitor that’s the gap between a usable layout and a cramped one, and it’s the one thing macOS native tiling has no answer for.
Splitting three or more windows
Two windows is the common case, but thirds and sixths widen it. Use the thirds shortcuts, or cycle into them, to line up three windows — browser, editor, terminal, say. On an ultrawide, sixths let you run six columns with nothing overlapping.
The real limit isn’t the app, it’s screen width. On a 13-inch laptop, two windows is the sensible ceiling. On a 34-inch ultrawide, three or four is comfortable — and that’s exactly where keyboard-driven snapping pays off, because dragging that many windows by hand turns tedious fast.
Drag-to-snap, if you prefer the mouse
Rectangle also does the Windows-style move: drag a window to a screen edge and it snaps to that half, a corner for a quarter, the top for maximize, with a translucent preview showing the landing spot before you release. If you came from Windows and miss Win+Arrow and drag-to-edge, this covers both halves of that habit — keyboard and mouse snapping in one app.
When something doesn’t work
Nine times out of ten, dead shortcuts mean the Accessibility permission got reset, which commonly happens after a macOS update. Return to System Settings → Privacy & Security → Accessibility, remove Rectangle for Mac, add it back, and restart the app. The other usual suspect is a shortcut conflict with another app claiming the same combination — remap either side and it’s done.
Whether you use Rectangle for keyboard shortcuts or its drag-to-snap zones, the result is the same: more control over your desktop. And if you pair it with Rectangle for Mac, you get both input methods in one free, open-source tool.
Frequently asked questions
What’s the keyboard shortcut to split screen on Mac?
With Rectangle installed, Ctrl + Option + Left Arrow snaps the active window to the left half and Ctrl + Option + Right Arrow to the right half. Do one, then the other with a second window, and you have a split screen. macOS alone has no equivalent single-keystroke shortcut for this.
Can you split screen on a Mac without an app?
Yes, partially. macOS Split View (hold the green button) and Sequoia’s built-in tiling both split windows without extra software. Split View pushes windows into a full-screen space, and native tiling lacks size cycling, sixths, and custom shortcuts — which is why many people install a dedicated app instead.
How do I split screen into three windows on a Mac?
Use thirds. In Rectangle, the thirds shortcuts (or repeat-pressing a halves shortcut to cycle into a third) place windows in left, center, and right columns. Three windows works comfortably on displays 27 inches and wider; on a laptop screen, two is usually the practical limit.
Why does my Mac split screen shortcut stop working?
Almost always the Accessibility permission was reset, typically by a macOS update. Re-grant it in System Settings → Privacy & Security → Accessibility and restart the app. The other frequent cause is another app claiming the same keyboard shortcut, which you fix by remapping one of them.