# PPI Calculator (Pixels per Inch)

URL: https://speedycalculator.com/calculators/other/ppi/
Last updated: 2026-10-25

> The PPI calculator finds the pixel density of a screen from its resolution and diagonal size, plus the dot pitch and the viewing distance at which individual pixels become hard to see.

## Inputs

- Horizontal pixels
- Vertical pixels
- Diagonal (in, cm)

## Results

- Pixel density
- Dot pitch
- “Retina” viewing distance
- Megapixels

## Formula

```
PPI = √(width² + height²) ÷ diagonal (in)
```

## Explanation

Higher PPI means sharper text and images. Phones often exceed 400 PPI; desktop monitors are usually 90–220 PPI.

### How to use the PPI Calculator

- **Horizontal pixels**
- **Vertical pixels**
- **Diagonal**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

The diagonal resolution in pixels is divided by the diagonal size in inches.

### Inputs explained

FieldWhat to enterHorizontal pixelsA numberVertical pixelsA numberDiagonalUnits: in, cm

### What each result means

- **Pixel density** = sqrt([Horizontal pixels]^2 + [Vertical pixels]^2)÷[Diagonal]
- **Dot pitch** = 25.4÷[Pixel density]
- **“Retina” viewing distance** = 3438÷[Pixel density]
- **Megapixels** = [Horizontal pixels]×[Vertical pixels]÷1e6

### Example values

How the main result changes when **Horizontal pixels** changes and everything else stays at the example values above:

Horizontal pixelsPixel density (PPI)1,28071.41,92088.92,560108.83,2001303,840151.95,120197

## Worked example

Inputs — Horizontal pixels: 2,560; Vertical pixels: 1,440; Diagonal: 27 in.

Results — **Pixel density = 108.8 PPI**; Dot pitch = 0.2335 mm; “Retina” viewing distance = 31.6 in; Megapixels = 3.69.

## FAQ

**What is a Retina display?**
One where pixels are not distinguishable at normal viewing distance for 20/20 vision.

**Is PPI the same as DPI?**
PPI is for screens; DPI is for printers, though people often use them interchangeably.

**What formula does the PPI Calculator use?**
PPI = √(width² + height²) ÷ diagonal (in).