What is PPI — and why does it matter?
PPI (pixels per inch) measures how densely a screen packs its pixels. It is calculated by dividing the screen's diagonal resolution in pixels by its diagonal size in inches: PPI = √(width² + height²) ÷ diagonal. Two screens can have the same resolution, but the smaller one will always look sharper because the same number of pixels is squeezed into a smaller area.
The higher the PPI, the crisper text and fine details appear. At phone viewing distance, Apple popularized the “Retina” threshold of roughly 300 PPI — the point at which most people can no longer distinguish individual pixels at a typical ~30 cm distance. Modern flagships routinely reach 450–520 PPI. For laptops and desktop monitors viewed from farther away, the comfortable threshold drops to around 220 PPI and 100–160 PPI respectively.
Practical buying guidance
- Phones: anything above ~400 PPI is effectively indistinguishable from the best; below ~320 PPI you may notice softness on small text.
- Tablets & laptops: aim for 220–270 PPI for crisp text work; a 14″ 16:10 laptop at 2560×1600 lands near 216 PPI, which is comfortable.
- Monitors: a 27″ 4K display gives ~163 PPI and sharp text, while a 24″ 1080p panel gives ~92 PPI — noticeably softer for long reading sessions.
PPI is only part of the story: panel technology (OLED vs IPS), refresh rate (60 vs 120+ Hz) and color coverage all shape the real-world experience. Use the device comparison tool to weigh two models side by side, the PPI calculator to compute density from any resolution and size, and the full device table to sort the whole database.
All specifications are a public snapshot and may change — always confirm with the vendor's official site.