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
| Field | What to enter |
|---|---|
| Horizontal pixels | A number |
| Vertical pixels | A number |
| Diagonal | Units: 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 pixels | Pixel density (PPI) |
|---|---|
| 1,280 | 71.4 |
| 1,920 | 88.9 |
| 2,560 | 108.8 |
| 3,200 | 130 |
| 3,840 | 151.9 |
| 5,120 | 197 |
Formula
PPI = √(width² + height²) ÷ diagonal (in)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.
Frequently asked questions
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).