I edit on an older 27" display that’s neither 2K nor 4K, it’s something in between: 2560 x 1440 pixels, which is still rather common. I’m still happy with it because my #1 priority is color accuracy, and it still calibrates well. I fully expect my next 27" display to be 4K or higher just because that’s more of the standard now, but 2560 x 1440 px has not held me back in any way for photo editing itself.
Because you mentioned sharpening for print, note that even if your display matches your printer dpi (e.g., 300 dpi, which many smartphone screens actually exceed now), a resolution match doesn’t guarantee perfect sharpening preview because digital displays don’t render image details the same way as a printer. Some of the traditional advice passed down (e.g., “always judge sharpening at 50% zoom”) was based on halftone screening (for a printing press) viewed on 1990s displays (72 to 110 dpi). That might not apply to how sharpening looks through FM screening (desktop inkjet printer) when previewed on a Retina (Apple) or HiDPI (Windows/Android) display. The best way to judge sharpening on screen is not to generalize from what someone else said based on a software/display/printer combination you don’t know, but instead do some test prints to understand how various amounts of sharpening look on your display for the printer you use.
Addressing your question above, the main thing that’s different between the choices you stated is the pixel density (1x, 2x…). That can be important for someone who wants to see sharper UI and text, or needs to properly preview graphics they design for 2x (Retina/HiDPI) displays. But for pure photography, pixel density is a lot lower priority than image quality (tone/color accuracy), so pixel density could be sacrificed on a limited budget.
If pixel density is a priority for you, then these are the differences you’ll see between 2K and 4K (and more):
| Inches (diagonal) | Panel dimensions in px | DPI (pixel density) | OS default scale factor | Effective UI dimensions | Megapixels |
|---|
| 27 | 1920 x 1080 (2K) | 81 | 1x | 1920 x 1080 @1x | 2.1 |
| 27 | 2560 x 1440 (QHD) | 109 | 1x | 2560 x 1440 @1x | 3.7 |
| 27 | 3840 x 2160 (4K) | 163 | 2x (Retina/HiDPI) | 1920 x 1080 @2x | 8.3 |
| 27 | 5120 x 2880 (5K) | 218 | 2x (Retina/HiDPI) | 2560 x 1440 @2x | 14.75 |
| 32 | 3840 x 2160 (4K) | 138 | 2x (Retina/HiDPI) | 1920 x 1080 @2x | 8.3 |
| 32 | 6016 x 3384 (6K) | 216 | 2x (Retina/HiDPI) | 3008 x 1962 @2x | 20.4 |
I threw in the Megapixels column because you might compare that to the megapixels in your cameras. The more they differ, the less you’ll be able to work at 1:1 and the more you’ll have to scroll or zoom. For example, if I had a 5K display it could show every pixel of my older 12MP camera at 1:1 with room left over for tools.
The first row shows that a 2K display at 27" is a rather low resolution display, because 27" is a long way to stretch out just 1920 pixels across. It can look a lot coarser than all other displays in the table, and although the effective working area is OK, it’s kind of minimal by today’s standards…not a lot of room to spread out windows and panels while leaving enough room over for the image you’re working on.
The last row represents the other extreme, the Apple Pro XDR display…when you look at the numbers you can see why Apple thought a 32" display should be 6K. We don’t have to agree with that, especially since most of us can’t afford that display, but what 6K buys you at 32" is both very large effective working area and 2x pixel density at the same time.
You can also see why Apple likes 5K for 27" displays: That results in perfect 2x pixel density of the traditional 2560 x 1440 px standard for 27".
The options you stated are the first and third rows in that table. Hopefully it will help you decide based on what kind of effective screen working area and pixel density you want. You can calculate your own numbers from many free monitor resolution calculator websites, that’s how I got those numbers.
For context, a typical 1x (legacy) desktop or laptop display is around 96–130 dpi, and a typical 2x (Retina/HiDPI) display is around 200–250 dpi.
