BenQ BL2420U review: a compact 4K monitor for gamers & professionals


The 24-inch BL2420U is the little brother of one of our favourite BenQ monitors at XSReviews, the BL3201PT. Like its peers, it comes with a full-sRGB IPS panel, an incredibly sharp 4K resolution and a plethora of special modes and added features. This was a winning combination at 32 inches, so how does it work at 24 inches and £380? Let’s find out.

Specifications & Features


  • 23.6-inch IPS panel with LED backlight
  • 16.7 million colours, 8-bit colour depth
  • 4K (3840 x 2160) resolution at 60 Hz
  • 100% sRGB coverage
  • Blue light reduction, CAD/CAM modes
  • 1000:1 native contrast
  • 300 nits brightness
  • 178 L/R, 178 U/D viewing angles
  • 7ms GTG response time


  • DisplayPort 1.2a, HDMI 2.0 (4K / 60Hz)
  • HDMI 1.4, DVI-D (4K / 30Hz)
  • 2x USB 3.0 passthrough
  • 3.5mm audio passthrough


  • Modes: sRGB, CAD/CAM, Animation (10 levels), Presentation, Standard, Low Blue Light (3 levels), Movie, Photo, Eco, M-Book, User
  • Adjustability: 25° tilt, 90° pivot, 140mm height adjust



The BenQ monitor is quite restrained and professional in its design, with just a few telltale signs that this is a higher class of monitor: relatively slim bezels, fancy touch-activated buttons and white LEDs. It’s worth noting that the blue trim in these press photos don’t appear to have made it to my review unit, but their absence isn’t problematic.

The ports are found in the traditional place, on the back of the monitor and facing down. This isn’t as convenient as the side-facing ports of BenQ’s larger monitors. There are plenty of ports here too, including DisplayPort 1.2a, two HDMI ports (one 2.0, one 1.4) and dual-link DVI.


The BL2420U has two USB 3.0 ports and a headphone jack on the back, which is handy for connecting additional peripherals such as mice, keyboards and gamepads.


The left and right sides of the monitors are clean, with no ports or features.

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The on-screen display itself is easily fiddled with, thanks to the convenient touch-activated buttons at the bottom right of the monitor. These are far better than small plastic buttons tucked away somewhere behind the monitor, which are all too often found on monitors that are otherwise high-end.


The BL2420U is a fine looking monitor, but it’s not here to look pretty — it’s here to do a job. Let’s take a look at how well it achieves it, starting with some synthetic benchmarks and moving on to our first-hand impressions.


First, we’ll look at the monitor’s gamut. As promised, it delivers 100% of sRGB, in addition to 79% of AdobeRGB and 75% of NTSC. That’s more than enough for most photo and video work, and well-suited for the professions targeted by this monitor.


We can already see a very good DeltaE value for white point and 50% gray, something that we’ll return to later with our colour accuracy benchmark. Brightness and white point are damn near perfect after calibration, too.

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Let’s look at how colour is represented across the monitor. Good, professional monitors should ideally provide a very uniform colour, so that an element (say, part of a photo) positioned in the corner of your monitor looks the same when it’s moved to the centre. The BL2420U does well here, with DeltaE values between 0.5 and 2.1 on maximum brightness, and 0.5 and 1.4 on 50% brightness. This is a very good score, and means that colours will not be dramatically different depending where they are physically on the monitor.


We can do the same test in terms of luminance; how different is each sector in terms of brightness? Here we see again quite strong results, ranging from 1% to 10%. The upper right and bottom left are the most different, but it’s not enough to compromise professional work.


Colour accuracy is another important consideration. With the exception of the turquoise shade (ID 1F), we see excellent colour accuracy across the board. The average DeltaE value, 0.97, is exactly where we hoped to see it.


Tone response is also on the money, adhering closely to the Gamma 2.2 standard.


All in all, the monitor is well suited for professional work, and has no obvious flaws.


Here’s what we thought of the monitor after one month of sustained use, both for work (writing, editing, photos and video production) and play (PC games including Fallout 4, StarCraft II, Counter-Strike: Global Offensive and UnderRail).


As a monitor for getting work done, the BL2420U unsurprisingly excels. The monitor’s accurate colour reproduction and 4K resolution are ideal for photo or video work, particularly for editing 1080p video as you have space for a 1:1 preview as well as your usual editing tools.


The monitor is also nice for writing; at 200% scaling you get very crisp text indeed. Having a 200% scale in Windows is much cleaner than the BL3201PT’s 150%, and you still have the option to drop it lower to increase the amount of on-screen space you have to work.

Having extra USB ports and easy controls also helps a lot, ensuring you can have your monitor and other equipment set up quickly and conveniently.

Adjustability is also important, and the BL2420U is also well equipped here. You can rotate the screen 90 degrees for portrait work, as well as adjust the tilt and height. The various professional modes — sRGB, animation, CAD/CAM — will doubtless be a welcome inclusion for users in those fields as well.


As a gaming monitor, the BL2420U is quite strong. Gaming at 4K is a demanding task (our test rig was able to handle medium settings on recent games like Fallout 4 with a Core i7 2600k and a Nvidia GTX970), but it does look fantastic. If you have a multiple-GPU or other high-end system, then you should be in for a treat. Even if you have a less powerful system, then you can still enjoy with older games like Counter-Strike: Global Offensive at 4K.


If you’re playing now fast-paced, competitive titles like DotA 2 or CS:GO, then a 144Hz monitor at 1080p or 1440p makes more sense than a 4K monitor at 60Hz. However, for all other titles, you may as well stick with the highest resolution you can hit 60fps with at your preferred detail settings. Gaming at 4K looks noticeably better than 1440p and vastly better than 1080p, so it’s well worth it if you can reach it.


The BL2420U is a brilliant monitor well suited for professionals and gamers alike; the 4K resolution and excellent colour reproduction ensure photos look true to life and games look sharp. Its high price is well justified by the quality of its panel, the attention paid to detail and the extras provided. If you’re looking for a compact 4K monitor with plenty of extras, the BL2420U should be at the top of your list.


  • 4K at 24 inches is a beautiful experience, whether working or gaming
  • Lots of ports and passthroughs ensure you’re always connected
  • Touch controls make for easy adjustments
  • Professionals are well catered for, with special modes and features


  • Gaming at 4K at optimum settings requires a beastly PC
  • 144Hz monitors will better suit competitive gamers
  • You do pay a premium for a professional-grade monitor; there are many cheaper, larger 4K monitors on the market
  • With 200% scaling, you’ll definitely notice low-resolution assets while browsing the web and using some programs




11 responses to “BenQ BL2420U review: a compact 4K monitor for gamers & professionals”

  1. Freek van der Heijden avatar
    Freek van der Heijden

    What were the monitor’s settings (color temperature – RGB) in the calibrated state?

    1. Both remained at their default settings.

      1. Freek van der Heijden avatar
        Freek van der Heijden

        The reason I asked that was because I thought it would be possible to ‘calibrate’ the monitor just by changing settings in the OSD. I now get the impression that the ‘calibrator device’ you were using changes the settings via a color profile, rather than the monitor’s settings.
        Is it wrong to assume that I can just use your calibrated color profile and use it on my computer? If so, could you provide me with that file?

        1. Hi Freek,

          Yes, that’s correct. Unfortunately, I don’t have the monitor or the color profile any more; the monitor has been returned and the computer I tested with has had Windows reinstalled. However, not every monitor will benefit from one colour profile, due to the variance between monitors. It’s probably better that you get or borrow a colorimeter (e.g. and run it against your particular panel. Sorry I couldn’t be of more help!



          1. Freek van der Heijden avatar
            Freek van der Heijden

            Thank you! I will look into that

  2. What about the contrast?

    1. The Spyder4Elite reads about 600:1, but it also chronically under-reads. The 1000:1 stated contrast should be accurate. I didn’t notice it being exceptionally good or bad, just okay.

      1. Ok thanks for your reply

  3. henri sormunen avatar
    henri sormunen

    How is the response time on this monitor, is it noticeable while gaming? Thanks for the review!

    1. The response time seems OK; it’s listed as 7ms rather than the 4ms of most IPS monitors. So not brilliant, but I didn’t feel disadvantaged playing CS:GO or other fast-paced games.

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