A MacBook next to an iMac on a wooden desk.

Want to be more productive on your Mac? Add another monitor, and you’ll spend less time switching between spaces, tabs, and windows. With Catalina, you can even use an iPad as a second monitor with the new “Sidecar” feature.

Pick a Monitor

First, you have to pick the right monitor for the job. Your budget will play a large role here, so first, decide what you want to spend, and which features are most important to you.

Here are some things to consider before you choose a monitor:

  • Resolution: This is the number of pixels displayed onscreen at once, measured on two axes (e.g., 1920 x 1080). Generally, the higher the resolution, the better the image quality. Higher resolutions, like 4K and 5K, require more powerful hardware.
  • Size: Most displays are around the 27-inch mark. Smaller, 24-inch displays remain popular with gamers, and people who have minimal desk space. Larger, 32-inch and ultrawide monitors are also available. Your decision ultimately depends on your budget and available space.
  • Pixel density: Measured in pixels per inch (PPI), pixel density describes how closely-packed the pixels are on the display. The higher the pixel density, the better the image quality, as you’re less likely to see individual pixels.
  • Display and panel type: This is the major factor when it comes to quality and performance. You can choose an LCD panel built on IPS, TN, or VA technology or opt for cutting-edge OLED panels if the budget allows.
  • Refresh rate: This refers to the number of times the display refreshes per second. The refresh rate is measured in hertz (Hz). Basic monitors support 60 Hz, which is fine for office work, web browsing, or anything without fast-moving images. Most high-refresh-rate monitors (144 Hz) are considered “gaming” monitors and would be overkill for those who aren’t.
  • Color accuracy: Which color profiles does the monitor support? If you use your monitor for creative work, like photo and video editing, or design, you need one with a high degree of color accuracy. You should also consider buying a monitor calibration tool.
  • Other characteristics: Do you want a curved monitor for a more immersive viewing experience? How about one you can use in portrait mode for coding or mobile development that tilts 90 degrees? Do you plan to mount the monitor on a VESA mount?

If you have the hardware and budget for a 4K monitor, the HP Z27 comes highly recommended from sites like Wirecutter. You can get the reduced, 1440p resolution version of the same display for a few hundred dollars less.

Apple says LG’s Ultrafine 5K display is suitable to use with its latest range of laptops. This display uses Thunderbolt 3 to drive the monitor and simultaneously provide 85 watts of charge for your laptop over USB-C. Acer’s XR342CK 34-inch curved display scores top marks for an ultrawide if you have the necessary desk space.

RELATED: How to Use Your iPad as an External Mac Display With Sidecar

Can Your Mac Handle It?

Technical Specifications for a MacBook Pro on Apple.com.

It’s important to make sure your Mac is powerful enough to drive any external displays at the resolution and refresh rate you need. One easy way to do this is to check the technical specifications of your particular model. To find your model, click the Apple logo in the top-right corner of the screen and choose “About This Mac.”

Search for your exact model on Apple’s website (e.g., “MacBook Pro Retina mid-2012”), and then click “Support” to reveal the technical specifications sheet. Under “Graphics and Video Support” (or similar), you should see something like, “Simultaneously supports full native resolution on the built-in display, and up to 2560 by 1600 pixels on up to two external displays.”

Recent MacBook Pro models can support four external displays at 4K, or two at 5K. Some people have connected more than the recommended number of displays successfully, although this usually results in a significant hit to performance.

Get the Right Adapters and Dongles

CalDigit Dual HDMI Thunderbolt 3 Hub

Depending on which Mac you use, you might already have everything you need to hook up an extra monitor or two. If you have a fairly recent MacBook, you might need to purchase a hub to get access to an HDMI or DisplayPort output.

There are three types of display connections you’re most likely to encounter:

  • HDMI: The same technology that connects Blu-ray players and consoles to your TV can carry video and audio. HDMI 1.4 is capable of up to 4K resolution at 30 frames per second (fps), while HDMI 2.0 can do 4K at 60 fps.
  • DisplayPort: This standard computer connection type for displays can carry video and audio. Often favored by gamers for its higher bandwidth connection, DisplayPort enables higher refresh rates, and thus, more frames per second.
  • Thunderbolt: This high-speed, active connection developed by Intel and Apple allows features like USB power delivery to charge laptops. It also allows daisy-chaining to connect multiple Thunderbolt devices in sequence.

You have to match your USB-C hub to your connector type. CalDigit produces a mini dock with dual-HDMI and a variety of other ports. You can also save some money and just grab a straight adapter, like the Thunderbolt 3 dual DisplayPort adapter from OWC. If you’re going the HDMI or DisplayPort route, remember not to waste money on overpriced cables.

Thunderbolt 3 monitors are another great choice. They use a simple “active” Thunderbolt 3 cable, which usually simultaneously charges your laptop. Apple’s official cables are $40 and “officially” supported, but you can find cables that cost half that online, like these from Zikko. Just make sure you get a certified, 40-Gbps cable that supports up to 100-watt charging.

You might also come across DVI and VGA monitors, although these are old and outdated now. Single-link DVI only manages slightly better than 1080p resolution and doesn’t carry audio. VGA is a deprecated analog connection. If you want to connect a DVI or VGA monitor, you’ll also need a specific adapter.

Arrange Your Displays

Now that you’ve arranged your monitors on your desk, plugged them in, and turned them on, it’s time to consider the software side of things. This is how you create a consistent experience between displays. You want your mouse cursor to flow naturally from one display to the other, and in the sequence in which they are arranged.

With your external display(s) connected, launch System Preferences > Displays. On your primary display (i.e., your MacBook or iMac screen), click the “Arrangement” tab. All detected displays are visible on the diagram. Click and hold on a display to show a red outline on the corresponding monitor. Uncheck “Mirror Displays” if you see the same image on both.

Now, click and drag your monitors to arrange them in the same order in which they sit on your desk. You can drag a monitor to any side of the screen, including above and below. Pay attention to the offset between the monitors, as this affects the point at which your cursor moves from one display to the other. Play around with the arrangement until you are happy.

Resolution, Color Profile, and Rotation

The "Display" tab on macOS.

With System Preferences > Display open, you see each display’s settings. This is where you change settings like resolution and refresh rate. Leave the resolution at “Default for this display” to use the monitor’s native resolution (recommended) or click “Scaled” to see a full list of available resolutions.

If you use your monitor in portrait mode for mobile development or text editing, you can set the current angle in the “Rotation” drop-down menu. Depending on which way your monitor articulates, you choose either 90 or 270 degrees. If you mount your monitor upside down for some reason, you can choose 180 degrees.

Click the “Color” tab to see the list of color profiles your display supports. Check the “Show profiles for this display only” box to see a list of officially supported profiles. Unless your monitor explicitly supports a third-party color profile (like Adobe RGB), you might encounter inaccurate colors when you use other settings.

RELATED: How to Match Colors on Your Multiple Monitors

Multiple Monitors and the Dock

macOS Dock Alignment and Preferences

The position of the dock can pose some issues when you use multiple monitors. The dock is supposed to appear on the “primary” display only, but how you arrange your displays can impact this. To change your primary display, head to System Preferences > Displays, and then click the “Arrangement” tab.

One of the displays will have a white bar at the top of the screen. Click and drag this white bar to set another display as the primary monitor. If you have the dock aligned at the bottom of your screen, you should now see it on your primary monitor.

The primary display in the "Arrangement" tab on macOS.

If you set the dock on the side of the screen where your external monitor connects to your MacBook or iMac, the dock appears on your external display regardless of what you do. You can’t “force” the dock to stick to your iMac or MacBook display. You either have to live with the dock at the bottom of the screen, change your display arrangement, or look at your external display to use the dock.

You can change the dock alignment under System Preferences > Dock.

Performance and Multiple Displays

Even if you don’t exceed the maximum number of supported displays according to your computer’s technical specifications, it’s worth it to consider how external displays affect performance. Your Mac only has so much processing power, particularly when it comes to graphics.

The more displays you use, the more of a performance hit your Mac is going to take. It’s a lot easier on your Mac if you use an external, 1080p display (1920 x 1080 = 2,073,600 pixels), rather than an external, 4K display (3840 x 2160 = 8,294,400 pixels). You might notice performance degradations, such as general slowdown, stuttering, or increased heat output.

Furthermore, if you put even more strain on your hardware with GPU-intensive tasks, like video editing, the drop in performance will be even more pronounced. If you use your Mac for these types of tasks, an external GPU (eGPU) might provide the extra power you need to drive external displays and get the job done.

External Monitors and MacBooks

A MacBook Air with its lid closed.

One of the best things you can do for your productivity is to add an external display to your MacBook (if it can handle it). Fortunately, you can opt to use only an external display, but you need a spare keyboard, and a mouse or Magic Trackpad to do so.

Simply connect your external display to your MacBook, log in as usual, and then close your laptop’s lid. The internal display goes to sleep, and your MacBook’s keyboard and trackpad are no longer accessible, but your external display won’t budge.

This allows you to take advantage of larger external displays while mitigating the performance hit associated with driving multiple monitors. It’s a great way to get a standard “desktop” experience from your normally portable MacBook. The only drawback is your MacBook might produce more heat in the closed position because it inhibits passive cooling through the keyboard.

Use Your iPad as a Display with Sidecar

If you have an iPad that supports iPadOS 13, you can also use your tablet as an external display. You can even use your Apple Pencil in macOS with compatible apps. It’s one of the many new features in macOS 10.15 Catalina that you can download for free from the App Store.

Profile Photo for Tim Brookes Tim Brookes
Tim Brookes is a technology writer with more than a decade of experience. He has covered a wide range of topics including Apple, security, productivity tips, gaming and more for publications like How-To Geek, Zapier, and MakeUseOf.
Read Full Bio »