Why a 3-Way Split Screen is the Best Way to Use an External Display with Your Mac

When you connect your Mac to an external display, you might be used to splitting the screen into two windows, left and right. However, after spending long hours working this way, I’ve found that splitting your screen into three sections can be much more comfortable—especially for your neck and shoulders. Here, I’ll share why I recommend a 3-way split and how you can set it up on your Mac.

Contents

3-Way Split Screens Help Reduce Neck Strain
How to Split Your Mac Screen into Three
Using 2/3 Width for Certain Apps
Recommended: 27-inch or Larger 4K Displays for Triple Split
Final Thoughts

3-Way Split Screens Help Reduce Neck Strain

The main reason I recommend splitting your screen into three sections is simple: it helps reduce the strain on your neck.

When you use a standard two-window split, you rarely look at both windows equally. In most cases, one side becomes your primary workspace, and you end up spending more time looking at that side.

As a result, you tend to keep your head turned at an angle for extended periods. This can put stress on the muscles on one side of your neck, which may lead to stiffness or shoulder pain over time.

Of course, I’m not a medical professional, so I can’t say for certain if this is medically accurate. But from my own experience, staring in the same direction for too long does make my neck hurt.

To improve this, I think it’s best to arrange your windows so that you can maintain a natural, forward-facing posture as much as possible.

When you use a two-way split, you often end up looking at just one side of the screen for long stretches. Keeping your head turned sideways like this can easily lead to neck pain.

That’s why I started using a three-way split: the main window sits directly in front of me, while the secondary windows are placed on either side. This setup helps me keep my head straight and reduces discomfort.

How to Split Your Mac Screen into Three

Instead, I recommend splitting your display into three windows. Place your main window in the center, with secondary windows on the left and right. This way, you can focus straight ahead most of the time and only glance sideways when needed.

But how can you actually set up a three-way split? Unfortunately, macOS’s built-in Split View only supports two windows. If you want to neatly divide your screen into thirds, you’ll need a third-party app.

I use an app called BetterSnapTool, which is available on the Mac App Store for $1.99 USD. It’s reasonably priced and well worth the cost for the productivity boost it brings.

BetterSnapTool is available for download from the Mac App Store. As of this writing, it costs $1.99.

With BetterSnapTool, you can drag windows to the edges or corners of your screen to automatically resize them—either to half, a quarter, or (importantly) a third of your display.

There’s also a menu bar icon, where you can quickly select “Left third”, “Middle third”, or “Right third” to snap your window to exactly one-third of your screen, perfectly aligned.

Selecting [Change Window Position/Size] → [Left third] resizes the window to one third of the screen and moves it to the left. Likewise, choosing [Middle third] or [Right third] places the window in the center or on the right, respectively.

If you find using the menu bar tedious, you can easily set up custom keyboard shortcuts—something I highly recommend. Personally, I use combinations like Control + Shift + Option + Arrow Keys. This avoids conflicts with other shortcuts and makes window management much faster.

To set up keyboard shortcuts, first click the menu bar icon and select [Preferences].

Click the [Shortcuts] tab at the top of the window that opens. Then, click the box next to [left third] and press your preferred key combination.

Repeat the same steps to set up shortcuts for [middle third] and [right third].

This allows you to resize and reposition windows instantly with just the keyboard—super efficient, especially on an M1 Pro MacBook Pro, where it runs smoothly with no issues.

Using 2/3 Width for Certain Apps

Some apps may feel cramped at just one-third of the screen. In these cases, BetterSnapTool also lets you set windows to two-thirds width, either on the left or right. You can access these options from the menu bar or assign them to custom shortcuts—for example, I use Control + Shift + Arrow Keys (without the Option key) for two-thirds splits, making it easy to remember.

Selecting [Left two thirds] or [Right two thirds] from the menu bar icon resizes the window to two thirds of the screen on the left or right side.

By setting up keyboard shortcuts under [Preferences] → [Shortcuts], you can resize windows even more easily.

Recommended: 27-inch or Larger 4K Displays for Triple Split

If you want to work comfortably with three windows side by side, I recommend using a 4K display of at least 27 inches.

I currently use the Dell U2723QE. Its native resolution is 3840×2160 pixels, but I run it at a scaled resolution of 3008×1692 on macOS. I choose this because it keeps UI elements like icons and the menu bar at a comfortable size. At this setting, each third of the screen is about 1003 pixels wide—plenty of space for my text editor (Jedit Ω) or web browsing in Safari.

If you try to do this on a smaller 23-inch display, each window gets pretty narrow, making it harder to work efficiently. That’s why a 27-inch or larger 4K display is ideal for three-way splits.

Using the maximum (More Space) setting gives you a larger workspace, but UI elements become smaller and harder to operate.

Some 27-inch monitors are sold with 1080p resolution for a lower price, but I strongly recommend going 4K or higher. Even the smallest MacBook Air (M1) has a 2560×1600 pixel display—so buying an external monitor with fewer pixels than your laptop isn’t a smart investment.

This is my current workspace. At first, I didn’t think I needed such a large display, but after discovering the benefits of using a three-way split, I now feel this is the best setup for me.

Final Thoughts

Upgrading to a large, high-resolution external display—and using a 3-way split—has made my workflow much more efficient. If you’re looking to boost your productivity with your MacBook setup, I highly recommend giving it a try.