5120×2160 (21:9 (64:27)) is a resolution, not a size. The same pixel grid can arrive on a 39″ panel or a 52″ one — and it looks and feels quite different on each. Here's the same 5K2K WUHD grid at 39″, 40″, 45″, 52″, drawn to scale.
| Size | Width × Height | PPI | Pixel pitch | How it feels |
|---|---|---|---|---|
| 39″ | 35.9″ × 15.2″ | 142 | 0.178 mm | Sharp — you may prefer slight UI scaling |
| 40″ | 36.9″ × 15.5″ | 139 | 0.183 mm | Sharp — you may prefer slight UI scaling |
| 45″ | 41.5″ × 17.5″ | 123 | 0.206 mm | Sharp — you may prefer slight UI scaling |
| 52″ | 47.9″ × 20.2″ | 107 | 0.238 mm | Comfortable — the common desktop sweet spot |
Resolution is only the pixel count. Stretch those pixels across a bigger diagonal and each one gets larger, so pixel density (PPI) falls — text and edges look softer, even though nothing about the resolution changed. Shrink the diagonal and density rises, giving crisper text but smaller UI that you may want to scale up.
For a normal desk viewing distance, roughly ~95–120 PPI is the comfortable range where the interface reads well at 100% scaling. Below that, pixels start to show; well above it, everything is sharp but the UI shrinks until you turn on OS scaling. Viewing distance matters too — the farther you sit, the more forgiving a lower PPI becomes.
So a 5K2K WUHD panel can be a crisp 39″ (~142 PPI) or a roomy but softer 52″ (~107 PPI) — same pixels, different experience.