Compare two screens' sharpness with PPI

A 27" 1440p monitor and a 24" 1080p one look similar on a shelf — but the pixel density differs. Put numbers on sharpness before buying.

Tools used in this guide

The job

Resolution alone does not tell you how sharp a display looks — 1920×1080 is crisp on a phone and coarse on a 27-inch monitor. PPI (pixels per inch) is the comparable figure: how densely the pixels are packed.

How to do it

Enter the horizontal and vertical resolution and the diagonal size in inches — or pick a preset to start from. The result is PPI plus dot pitch (the physical size of one pixel), megapixels, and the reduced aspect ratio.

Typical references: ~96 PPI classic desktop, ~110 PPI 27" QHD, ~160 PPI 27" 4K, 450+ PPI phones.
Dot pitch = 25.4 ÷ PPI; smaller means finer.
Run it twice to compare two candidates side by side.

Worked example

2560×1440 on 27 inches: diagonal pixels √(2560²+1440²) ≈ 2937, ÷ 27 ≈ 108.8 PPI, dot pitch 0.233 mm. The same resolution on 24 inches rises to ~122 PPI — noticeably crisper at the same desk distance.

Limits

PPI says nothing about panel quality, color, or scaling comfort — operating systems can render larger UI on high-PPI screens, changing how much fits. Advertised diagonals are nominal and rounded; check the spec sheet when precision matters.