---
title: "Pixel density (PPI) calculator — free, runs in your browser"
description: "Pixels per inch from resolution and screen size, with viewing distance guidance. Free, no sign-up, and nothing you enter leaves your browser."
url: https://atoneplace.net/tools/pixel-density-calculator/
site: "At One Place"
---

# Pixel density (PPI) calculator

Pixels per inch from resolution and screen size, with viewing distance guidance.

## How it works

Calculates pixel density from a resolution and a diagonal screen size. The diagonal in pixels is the Pythagorean combination of width and height, divided by the diagonal in inches.

Density on its own says nothing about whether a screen looks sharp — viewing distance decides that. The human eye resolves roughly one arcminute of detail, which works out at about 60 pixels per degree. A phone held at 30 cm needs around 300 PPI to be beyond that limit; a television at three metres needs about 30. This is why a 4K phone is largely wasted while a 4K television at normal viewing distance is not, and why comparing PPI figures across device classes is meaningless.

The tool reports the distance at which a given density becomes indistinguishable from a higher one, which is the figure actually worth knowing.

> This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.

## Common questions

### How do you calculate PPI?

Take the square root of width squared plus height squared in pixels, then divide by the diagonal in inches. A 1920 × 1080 24-inch monitor is about 92 PPI.

### What PPI do I need?

It depends entirely on viewing distance. Roughly 300 PPI for a phone at 30 cm, 110 for a monitor at 60 cm, and 30 for a television at three metres.

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## Sources

- Calculated on this page — At One Place (/about/)