LG UltraFine 40U990A-W
39.7" IPS · 5120× 2160 · 140 PPI
Optimal Viewing Distance
62cm
Retina distance: 62.4cm / 24.6in
Too Close
< 19cm
Perfect Zone
62cm
Good Zone
94cm
Acceptable Zone
1.6m
Too Far
2.5m
62cm Perfect Zone
Retina quality — pixels are invisible at this distance.
94cm Good Zone
Sharp image — slightly past the ideal distance but still excellent.
1.6m Acceptable Zone
The screen appears smaller — you're starting to miss fine details.
2.5m Too Far
You're not using your screen's full resolution. Move closer.
Specifications
| Brand | LG |
|---|---|
| Model | UltraFine 40U990A-W |
| Screen Size | 39.7" |
| Resolution | 5120×2160 |
| Panel | IPS |
| Refresh Rate | 120 Hz |
| Variable Refresh Rate (VRR) | FreeSync Premium |
| Response Time | 5 ms GTG |
| HDR Certification | DisplayHDR 600 |
| SDR Brightness | 450 nits |
| HDR Peak Brightness | 600 nits |
| Contrast Ratio | 1:2,000 |
| Ports | 2x HDMI · 1x DP · USB-C · USB Hub |
| Color Gamut | sRGB 100% · DCI-P3 99% |
| Viewing Angle | 178° — Excellent |
| Pixel Density (PPI) | 140 |
| Aspect Ratio | 21:9 |
| Year | 2025 |
Category Ranking
Pixel Density (PPI)
#30 / 67in category
93 PPI140 PPI224 PPI
HDR Peak Brightness
#22 / 67in category
250 nits600 nits2000 nits
DCI-P3 Color Gamut
#2 / 63in category
79%99%100%
Refresh Rate120 Hz
StandardHighUltra
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Frequently Asked Questions
What is the optimal viewing distance for the LG UltraFine 40U990A-W?
The optimal viewing distance for the LG UltraFine 40U990A-W (39.7") is approximately 62cm. At this distance, individual pixels become invisible to the human eye.
What is the PPI of the LG UltraFine 40U990A-W?
The LG UltraFine 40U990A-W has a pixel density of 140 PPI (pixels per inch) with a 5120×2160 resolution on a 39.7" display.
Is the LG UltraFine 40U990A-W good for desktop work?
With 140 PPI and a 39.7" IPS display, the LG UltraFine 40U990A-W is very good for desktop work when viewed from the recommended distance of 62cm.
Methodology & Sources
Formula: Retina distance (cm) = 3438 / PPI. Displayed values are rounded for readability.
Sources: Official manufacturer spec sheets and product pages. Specs are normalized before comparisons.
Last updated:
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