Choosing an external display for macOS

[nicnic77]

I'm reading all over the place that the macOS UI is best suited for a PPI of either 110 (non-retina) or 220 (retina) and anything in between should be avoided because it will result in less than optimal sharpness and excessive strain on the CPU.

Here's an interesting blog post about it:

Choosing an external display for macOS - Three f plus one

So considering all of this, I'm looking for dual 27" monitors. There are various configurations of PPI including:

27" 5k = 217 PPI
There are be no 27" 5k monitors on the market, except the iMac.

27" 4k monitors = 163 PPI
There is an endless supply of these, but the PPI is not-optional

27" 1140p = 108 PPI
There is an endless supply of these, and the PPI is optional

This would lead me to believe that I need to look for 1140p monitors. However, a number of other people are telling me that 27" 4k monitors are absolutely fine!

rtings.com recommend 1140p monitors over 4k and ignore all Dells:

The 6 Best Monitors For Mac Mini - Spring 2025

The best monitor for Mac Mini that we've tested is the Acer Nitro XV275K P3biipruzx. It's a 4k, 27-inch monitor that's great for a variety of uses.

www.rtings.com

So who do I believe! What are your experiences?

 

[Stephen.R]

The performance issue is entirely dependent on your Mac and how many displays you want to run.

yes a display at a non-optimal hidpi resolution isn’t quite as sharp as if it were at optimal hidpi resolution, but it’s still better than non-hidpi (ie a 4K 27” at “looks like 2560x1440” will still look better than a native 2560x1440 display, for most people.

Having said that personally I find 24” 4k’s to be a better compromise than a 27. ~21” 4K would be ideal, but 24” 4K beats that on account of being a product that exists for sale.

 

[nicnic77]

The performance issue is entirely dependent on your Mac and how many displays you want to run.

yes a display at a non-optimal hidpi resolution isn’t quite as sharp as if it were at optimal hidpi resolution, but it’s still better than non-hidpi (ie a 4K 27” at “looks like 2560x1440” will still look better than a native 2560x1440 display, for most people.

Having said that personally I find 24” 4k’s to be a better compromise than a 27. ~21” 4K would be ideal, but 24” 4K beats that on account of being a product that exists for sale.

I've got a MacMini M1 on order, and want dual screens. Already own 2 4k monitors (LG Ultrafine) but can't run two TB3 monitors from the M1.

So another vote for ignoring the 10/220 PPI thing and going 4k, not 1440p...

 

[McGiord]

Have you check this? https://www.macrumors.com/2020/11/24/m1-macs-able-to-run-six-external-displays/

Did you decide on which one to buy?

I'm looking for 2 external monitors to have next to my 27" 5K iMac (late 2015).

 

[nicnic77]

Have you check this? https://www.macrumors.com/2020/11/24/m1-macs-able-to-run-six-external-displays/

Did you decide on which one to buy?

I'm looking for 2 external monitors to have next to my 27" 5K iMac (late 2015).

I went for 2 of these:

27” UHD 4K Monitor - 27UL850 | LG UK

Discover LG 27UL850. Click for pictures, reviews, and tech specs for the LG 27” UHD 4K Monitor.

www.lg.com

I agonised over PPI but now I don’t know what all the fuss is about. Despite what plenty of people say, 4K 27” monitors are perfectly sharp. They’re hooked up to an i7 MM until 18th Dec when the M1 arrives and the Intel is returned.

 

[McGiord]

Thanks for the info. I finally bought only one of this, now looking for a wall mount to hold next to my iMac 27"

LG UltraFine UHD 27-Inch 4K UHD 2160p Computer Monitor 27UN850-W, IPS with VESA DisplayHDR 400, AMD FreeSync, and USB-C, White,Silver

Upgrade to an LG UltraFine IPS 4K screen, delivering ultra HD resolution with supremely accurate colors, even when viewed off-angle. The 27-inch display offers versatility of USB Type C connectivity (60 Watt power delivery) plus the benefits of HDCP 2.2 compatibility, so it will seamlessly displa...

www.amazon.com

 

[RedTheReader]

27" 5k = 217 PPI
There are be no 27" 5k monitors on the market, except the iMac.

There’s the LG UltraFine 5K. The 2016 model or the 2019 refresh.

LG UltraFine 5K Display - Apple

Apple Store Search Results

www.apple.com

Having said that personally I find 24” 4k’s to be a better compromise than a 27. ~21” 4K would be ideal, but 24” 4K beats that on account of being a product that exists for sale.

There’s the LG UltraFine 4K. This one is tricky, because there are many models with the same name apart for the one that was endorsed by Apple. I’m talking about the 21.5” model from 2016.

LG 22'' Class UltraFine™ 4K IPS LED Monitor (21.5'' Diagonal) (22MD4KA-B) | LG USA

Get information on the LG 22'' Class UltraFine™ 4K IPS LED Monitor (21.5'' Diagonal) (22MD4KA-B). Find pictures, reviews, and tech specs.

www.lg.com

 

[Stephen.R]

There’s the LG UltraFine 4K. This one is tricky, because there are many models with the same name apart for the one that was endorsed by Apple. I’m talking about the 21.5” model from 2016.

Yep, but AFAIK the 21.5" model is discontinued isn't it?

It's quite surprising to me that there's so little market for high-PPI computer displays, given how crazy phone PPI counts are getting. Sony released a phone with ~800 PPI 3 years ago. But we can't get any product variety on ~220 PPI at desktop sizes?

Dell even had a 5K 27" for a while, but that got canned. Even with the 24"s I have, it's plenty workable for non-pixel-perfect work (I'm not gonna tell a graphic designer what works for them, but for anyone dealing with text, they're superb); but they're also apparently end of life, because almost nowhere (here) has them. If I find somewhere that has any I'm likely to buy a third, because at this point I dont think I can assume any better alternative is going to be available any time soon from either Dell or from other manufacturers. I'd consider the current 24" 4K LG that Apple sells, but (a) it's USB-C/TB3 only: I can't run it from an eGPU. (b) it's literally twice the price of the Dells that I bought.

 

[SO8]

I'm just searching for a decent 27" monitor ... got as far as ordering the LG Ultrafine 5K display but cancelled it after reading some stuff which said it was probably being replaced !

I am struggling with all the monitors and their spec's ! I bought a Lenovo at £166 but it stutters when I watch Netflix though on normal PC stuff it is ok.

I use Lightroom and need a monitor that is super fine quality. The Lenovo will be going back but I can't decide what to get !!

​

 

[nicnic77]

After a lot of deliberation I went for 2 x 27” 4K LG 27UL850’s. Not 110ppi, or 220ppi as some people recommended, it’s actually bang in the middle - which should be be very sub-optimal. Well, my are fine and I wish I’d not spent so much time researching it all...

 

[McGiord]

After a lot of deliberation I went for 2 x 27” 4K LG 27UL850’s. Not 110ppi, or 220ppi as some people recommended, it’s actually bang in the middle - which should be be very sub-optimal. Well, my are fine and I wish I’d not spent so much time researching it all...

Your post help me to narrow it down. I learned yesterday about the letters and the years:

Some reported having issues with the USB ports and sleep mode with 2018 model.

 

[RedTheReader]

Yep, but AFAIK the 21.5" model is discontinued isn't it?

Yes, it’s discontinued unfortunately. But because it was such a popular display amongst the Mac community, you can still find them 2nd hand easily. It’s really the pricing that’ll get you, because they weren’t exactly cheap monitors to begin with. My usual recommendation would just be the current 24” 4K model that Apple sells, but because it’s a normal UHD resolution instead of something custom, I understand that it may be hard to justify.

It's quite surprising to me that there's so little market for high-PPI computer displays, given how crazy phone PPI counts are getting. Sony released a phone with ~800 PPI 3 years ago. But we can't get any product variety on ~220 PPI at desktop sizes?

It’s odd indeed. From what I’ve been seeing since about 2014, it’s only Apple that seems to care about maintaining “retina” level pixel density on desktop displays. First it was with the 5K iMac, then the bespoke LG monitors mentioned above, and finally the Pro Display XDR. Meanwhile on the open monitor market there’s been… nothing. At this point I’m forced to either stick with my 5K UltraFine for a long, long time, or just accept that resolution on other monitors will be secondary at best.

I'm just searching for a decent 27" monitor ... got as far as ordering the LG Ultrafine 5K display but cancelled it after reading some stuff which said it was probably being replaced !

I haven’t hear any such thing myself, but I have heard strong rumors of iPads, MacBooks, and iMacs getting miniLED displays. That’s a huge shift in panel technology. Apple cared enough to get the LG 5K UltraFine pushed out after the 5K iMac for their MacBooks (though it did take a while), so I’d imagine a revamped monitor will probably be released with miniLED. As for whether Apple will partner up with another brand to do it or just take matters into their own hands, I’m really not sure.

In any case, yeah, I can imagine our LG monitors getting successors soon. Personally, I’m kind of attracted to the 5K2K (5120 x 2160) 40” ultrawide that’s slatted for spring 2021. It’s not going to be a pixel-peeping display though, since the pixel density’s going to be the same as a normal 4K 32” monitor.