Although Apple laptops and desktops have lots of virtues, the ease of finding fully compatible peripherals is not one of them. We were glad to have a chance to review LG's $699.99 UltraFine 4K Display (24MD4KL-B), one of the few resolutely Mac-centric monitors to have hit the market. This 24-inch monitor shows seamless compatibility with the MacBook Pro we tested it on, and it's also compatible with recent iPad Pros. It offers some essential, forward-looking ports (while leaving certain other, more common ports off), and it's geared to support Apple's standard color space. It's a little pricey, but it's a good choice if you have a Mac desktop setup and need a sharp, not-too-big display. Be forewarned, though: It won't work well moonlighting as a Windows-PC-connected panel, and the look of the chassis isn't quite as Mac-minded.
An Underserved Niche
You won't find all that many 24-inch 4K (3,840-by-2,160-pixel) monitors—that native resolution is found almost exclusively on displays with larger screens. Those that are available tend to retail for less than $400. And even fewer monitors have been introduced that are specifically geared to the Mac. In addition to the 24MD4KL-BL, LG has a 27-inch 5K monitor, the 27MD5KA-B, but that's about all you'll find. Apple itself has announced it will release its own ultra-luxe new-generation monitor in the fall, but for five grand—and if you want a stand for it, that's a thousand bucks more.
What makes for a good Mac monitor is largely the same set of things that makes any monitor good: a sturdy, adjustable frame, a native resolution and screen size that complement each other, accurate rendering of colors, and a useful selection of ports. I'll discuss how the 24MD4KL-B stacks up against these criteria throughout the review, but let's first discuss some of its Mac-specific virtues.
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As mentioned, this panel can be used with recent MacBook Pros and iPad Pros, or as a second display for an iMac Pro or a recent iMac. (You'll want to hook it up via a Thunderbolt 3 port in the case of the Macs, or via the USB Type-C port found on the latest iPad Pros.) The monitor integrates well with macOS, and you can change its settings directly from your Mac's Display dialog. Also, it covers more than 97 percent of the DCI-P3 color space, a version of which Apple uses as its standard wide-gamut color space.
Note that the 24MD4KL-B is so Mac-centric that this is not a model to consider if you're looking for a Windows (or even a dual-use Windows/Mac) monitor. We were able to use it with several Dell XPS and Razer laptops using DisplayPort over their compliant Thunderbolt 3/USB-C ports, but, by a long shot, not every laptop will have this kind of connectivity.
Indeed, the monitor turns on automatically when you connect a laptop to it via a Thunderbolt 3 port, and the monitor has no dedicated onscreen display (OSD) from which to control settings. Mac users can change some display settings in macOS itself, but Windows users don't have that option. (The only setting I was able to control through my Dell XPS 13 was the audio volume for the panel's built-in speakers.) And as I discuss below, although you may be able to mod the 24MD4KL-B to work better with Windows, unless you live to tinker, it's more trouble than it's worth.
The 24MD4KL-B has a 24-inch (measured diagonally) IPS panel with a native resolution of 3,840 by 2,160 pixels, for a 16:9 aspect ratio. This translates to a pixel density of 186 pixels per inch (ppi). While this is impressive for a monitor in its general size class (for example, two 27-inch 4K models we've tested, the Acer Predator X27 and the ViewSonic VP2785-4K, have 163ppi pixel densities), it is low for the Mac world. (Generally, the higher the pixel density, the sharper the image.)
Take, for one, the screen in the 2019 Apple iMac 27-Inch with 5K Retina Display. It has a pixel density of 228ppi. The latest 15-inch MacBook Pro, meanwhile, comes in at 220ppi, and the iPad Pro (the 12.9-inch 2018 version) has a 264ppi measure. Now, granted, you'll be viewing content at close quarters on your iPad (or for that matter, your laptop), so a very high pixel density there makes sense. Still, the 24MDKL-B's 186ppi is nothing to sneeze at—it can produce a sharper image than most any monitor we have tested at its size.
A Minimalist Monitor
The 24MD4KL-B's design is simple and understated, though not unattractive. The cabinet and stand are both matte black, and look elegant enough, but to my eyes they are not particularly complementary to Apple's mostly silver hardware. Factoring in the stand, the 24MD4KL-B measures 16.4 by 21.8 by 9 inches (HWD), with the height increasing to 21.4 inches when fully extended, and it weighs 15 pounds.
The panel has half-inch bezels on the sides, top, and bottom. The back of the cabinet is beveled, tapering to meet the stand, which affixes to the monitor with a removable plate. The stand supports height and tilt adjustment. It can even be pivoted a few degrees for leveling purposes, much as you'd adjust a crooked picture frame. It comes with a 100mm VESA bracket should you want to wall-mount it instead.
Also in back is a socket for the power cord (the power supply is internal, so there's no power brick), as well as a slot for a locking security cable, and five ports, which I'll discuss below. The monitor is free of buttons or controls, which is a bit of an oddity in this Windows-centric world.
All USB-C and Thunderbolt, All the Time
The ports on the back panel are five in a row: three USB Type-C, and two Thunderbolt 3. All of them employ the same physical connectors, but the Thunderbolt 3 ports allow for much faster data transfer (up to 40Gbps, compared with 10Gbps for USB-C alone). Newer MacBook Pros are bristling with USB Type-C/Thunderbolt 3 ports; the 2016 15-Inch MacBook Pro that I used in testing has four USB-C/Thunderbolt 3 ports (its only ports, other than a headphone jack). My own Dell XPS 13 has two Thunderbolt 3 ports and one USB-C.
It's great that the 24MD4KL-B includes so many USB-C and Thunderbolt ports. (With a pair of Thunderbolt 3 ports, you can daisy-chain devices, connecting the panel to your Mac with one of the ports and onward to some other Thunderbolt 3 peripheral with the other.) The Thunderbolt 3 ports support power delivery of up to 85 watts, so you can quickly charge your late-model Mac laptop at the same time you're streaming content from it.
While the ports on the 24MD4KL-B are powerful, useful, and forward-looking, they are limited in variety. Your monitor may be future-proofed, but we're still living in the present, where many devices lack USB-C—let alone Thunderbolt 3—connectivity. They may connect via HDMI, USB Type-A, or even Thunderbolt 2 ports (like my five-year-old 15-inch MacBook Pro), the last of which uses a wholly different connector than Thunderbolt 3. You can buy solutions, of course: adapters and docks, though they're an extra expense and can be a hassle. You'll only want to go with this LG panel if your Mac and your peripherals are resolutely ready for USB-C/Thunderbolt 3.
Look, Ma, No Buttons
As I noted earlier, the monitor lacks any buttons or controls, and it doesn't even have an on/off switch. You control it directly from your Mac, using options in its Display dialog box. The settings you can tweak are more limited than with most monitors, but you can control brightness and resolution, change the color space, and go into "night mode," which makes colors warmer (reducing blue light), for instance. You turn the 24MD4KL-B on simply by connecting your MacBook to one of the monitor's Thunderbolt 3 ports.
You could also turn the 24MD4KL-B on by connecting it to a Windows machine, but your experience will be very limited. When I tried it with my Windows laptop (a Dell XPS 13), fuhgeddaboutit. It would render the laptop's screen contents, even display videos, but without the Mac's "seamless" integration, I had almost no control over settings. The monitor would not charge my laptop over the Thunderbolt 3 connection, nor could I change the brightness or color space. About the only thing that did work was controlling the volume of the 24MD4KL-B's onboard speakers.
In perusing support forums, I see that some people got this monitor to work with Windows machines, but only by adding a Thunderbolt 3 expansion card to the computer's motherboard (in the case of a desktop PC), tweaking the BIOS, and/or various other fixes. Even then, many people reported only partial success, with some functions still disabled. My advice? I'd turn back, if I were you. Don't buy the 24MD4KL-B if you don't have a Mac, and if you want to use it with a Windows machine alongside your Mac, prepare for some experimentation and the possibility of having only limited control over the picture.
Dazzling Brightness, Video and Photo Friendly
I measured brightness, color accuracy, and black level using a Klein K10-A colorimeter and the SpectraCal CalMAN 5 software.
The 24MD4KL-B's luminance (that is, its brightness per unit area) is rated by LG at 500 candelas per meter squared (nits); it measured at a brilliant 538 nits, the highest brightness I've recorded in a non-gaming monitor. In addition, I calculated its contrast ratio at 1,350:1, slightly better than its 1,000:1 rating.
According to LG, this panel is factory-calibrated to cover 98 percent of the DCI-P3 color space; CalMAN turned in a very close 97.5 percent result in our testing. Below is a color fidelity or chromaticity chart. The area within the triangle represents the DCI-P3 color space, and my data points (the circles) are the colors as we measured them. This color space, originally geared to digital cinema projection, is nearly identical to the Display P3 color space that is the standard on Macs.
Beyond these formal tests, I viewed a selection of our test clips, and it was a pleasure to watch video on the 24MD4KL-B. It showed vivid colors and had good dynamic range. The pair of built-in 5-watt speakers provides reasonable volume and sound quality for in-monitor speakers. Photos showed good contrast, and colors seemed true.
LG includes a one-year standard warranty with the 24MD4KL-B, which is meager, particularly considering the product's price. Most monitors are backed by three-year warranties.
A Boon to Mac Users
The LG UltraFine 4K Display (24MD4KL-B) has a lot to offer to Mac users. (Once again, note that it's a pure Apple play, not designed for Windows users.) Its virtues include a bright image with good color for both photos and video, good coverage of the Mac standard DCI-P3 color space, seamless integration with MacBooks, and compatibility with recent iPad Pros. Its relatively small screen, combined with a high (4K) native resolution, makes for high pixel density and a sharp image. But like most things in the Mac world, you do pay a premium for it—albeit, not as much as you'd shell out for LG's 27-inch 5K counterpart, the UltraFine 5K Display (27MD5KA-B), which lists at $1,299.99.
LG's UltraFine 4K Display (24MD4KL-B) is a pin-sharp, if pricey, pick as a Mac-friendly monitor, designed to pair with an Apple desktop or laptop equipped with Thunderbolt 3.
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