PPI (pixels per inch) is the number of pixels packed into one linear inch of a display, calculated from the diagonal pixel count divided by the diagonal size in inches.

What PPI counts as "Retina" or high-density?

There is no fixed cutoff, but displays viewed at arm's length (phones, tablets) are usually considered high-density above roughly 300 PPI. Monitors viewed further away look sharp at lower PPI, often 100-140.

Is PPI the same as DPI?

They are related but not identical. PPI describes pixel density on a screen; DPI (dots per inch) describes printed dot density. The terms are often used interchangeably for displays, but DPI technically applies to print output.

How do I find my screen resolution?

Check your device or monitor specs page, or your operating system's display settings, which usually list the native resolution in pixels (for example 1920 x 1080).

Does a higher PPI always look better?

Higher PPI means finer detail, but the benefit depends on viewing distance. Beyond a certain PPI at a given distance, the human eye cannot resolve additional detail, so diminishing returns apply.

Dot pitch is the physical size of one pixel, expressed in millimeters. It is the inverse of PPI converted to metric: 25.4 divided by PPI.

PPI Calculator

Name: PPI Calculator
Availability: InStock
Author: Nham Vu

Enter screen resolution and diagonal size to get pixels per inch (PPI) and pixel density.

Screen Specs

Device Preset

Width (px)

Height (px)

Diagonal Size (inches)

Enter resolution and screen size to see results

Summary

Enter screen resolution and diagonal size to get pixels per inch (PPI) and pixel density.

How it works

Enter the horizontal and vertical resolution in pixels, or pick a device preset.
Enter the diagonal screen size in inches.
The tool computes the pixel diagonal using the Pythagorean theorem.
PPI is the pixel diagonal divided by the physical diagonal.
Dot pitch (the physical size of one pixel) is shown as the inverse of PPI, in millimeters.

Use cases

Compare pixel density between two monitors or phones before buying.
Check whether a display qualifies as "Retina" grade (roughly 300+ PPI at normal viewing distance).
Estimate print sharpness expectations when mirroring a screen resolution to a physical size.
Verify a manufacturer's advertised PPI figure.
Plan UI scaling for a custom-built monitor or embedded display.
Size a projector or TV screen for a target pixel density.

Frequently Asked Questions

Last updated: 2026-07-21 · Reviewed by Nham Vu