Use the iMac 2019 (27-inch 5K) as a monitor
The 27-inch 5K iMac from 2019 is the first iMac that can be a monitor for another Mac in two ways: wirelessly with Apple's AirPlay, or over one Thunderbolt cable with DisplayBridge, the app I develop.
In short: AirPlay is free and fine for the occasional presentation. For everyday work at the panel's full 5K, DisplayBridge is the better fit. I haven't had a 2019 on my desk yet, but it has the same Thunderbolt 3 ports as the 2017 and 2020 models I've tested, so it should work the same way.
The iMac 2019 in facts
| Full name | iMac (Retina 5K, 27-inch, 2019), model number A2115 |
|---|---|
| Display | 5120 × 2880 pixels, 500 nits, wide color (P3) |
| Thunderbolt ports | Two Thunderbolt 3 (USB-C) ports on the back |
| Last macOS | macOS 15 Sequoia |
| DisplayBridge | Should work (same ports and macOS support as the tested models), not tested yet |
| AirPlay to Mac | Yes, it can receive AirPlay |
| Target Display Mode | No |
| Used price (eBay US) | Median $499; half of all working units sold between $325 and $650 |
What DisplayBridge is
DisplayBridge is the app I develop for exactly this job: using one Mac as a display for another. The same app runs on both Macs; you connect them with a Thunderbolt cable, click Connect, and the iMac appears in System Settings as a second display of your Mac. Unlike AirPlay, the picture is uncompressed at the full 5K and 60 Hz, and the sound can play on the iMac. When you disconnect, the iMac is a normal Mac again. It costs $29 once after a free 7-day trial; the iMac that shows the picture never needs a license.
AirPlay or DisplayBridge on the iMac 2019?
Since macOS Monterey, the 2019 iMac can receive AirPlay from another Mac and act as its extended display. It is free and wireless, which makes it the easiest choice for showing a presentation or a video on the big screen. The picture is sent as compressed video, though, and doesn't run the panel at its native 5K, so text is softer and there is a noticeable delay when you work with the mouse.
DisplayBridge connects the two Macs with one Thunderbolt or 40 Gbit/s USB-C cable in one of the iMac's two Thunderbolt ports. The picture arrives uncompressed at the full 5120 × 2880 pixels and 60 Hz, the delay is roughly 10 milliseconds longer than with a directly connected monitor, and the sound plays through the iMac's speakers. It costs $29 once, after a free 7-day trial. My Target Display Mode guide compares the two side by side, and the step-by-step guide shows the DisplayBridge setup.
Known weak points of the iMac 2019
The 2019 has no well-known screen defect, but its standard configurations come with a Fusion Drive: a hard disk combined with a small piece of flash storage. It is slow, and it is the part that most often fails on these iMacs. For use as a display, the speed doesn't matter much, since the iMac only has to start up and run DisplayBridge. A failing drive, however, means it may no longer start at all. When you look at one, let it start up from off, use it for a few minutes, and run First Aid in Disk Utility. Models with an SSD instead of a Fusion Drive avoid the problem.
Like every 5K iMac, check the screen edges for a pinkish tint on a white background; the problem is best known from the 2015 model, but it is worth ruling out on any 5K iMac.
What a used iMac 2019 costs
Working 27-inch 5K iMacs from 2019 sold on eBay in the US for a median of $499 in the last three months; half of them went for between $325 and $650. The top configurations with a Core i9 and the Radeon Pro Vega 48 sell for much more. If you only need a monitor, the 2017 model is the better deal at about $280 for a display of the same class. The 2019 makes sense if you also want a Mac that runs macOS Sequoia.
Before you buy one, go through the checklist on my iMac 2017 page: Thunderbolt ports, screen edges, Apple Account and Find My, company management (MDM) and firmware password. Like the 2017, the 2019 has no T2 chip and therefore no Activation Lock in hardware, so the seller signing out of their Apple Account is what matters.
Prices: eBay US sold listings, condition "Used", July to October 2026, without listings for parts, damaged or locked units, and without sellers with no positive feedback. Checked on 11 October 2026.
Questions about this
Should I use AirPlay or DisplayBridge with an iMac 2019?
AirPlay if you only need the big screen now and then and want it wireless; it costs nothing. DisplayBridge if you want to work on the iMac every day: the picture is uncompressed at the full 5K and 60 Hz over a cable, and the sound plays on the iMac too. It costs 29 dollars once, after a free 7-day trial.
Has DisplayBridge been tested with the iMac 2019?
Not yet. I've tested the 2017 and 2020 models and the iMac Pro. The 2019 sits between them, with the same two Thunderbolt 3 ports and support for current macOS versions, so it should work the same way. The free trial is the easiest way to check it on your own iMac.
Is an iMac 2019 worth buying just to use as a monitor?
Only if you also want a newer Mac. As a pure monitor, the 2017 model has a display of the same class and sells for roughly half the price: about 280 dollars against about 500 dollars for a working 2019 on eBay in the US.