Pixels Per Inch (PPI) Calculator

$PPI = \frac{\sqrt{{width_px}^{2} + {height_px}^{2}}}{diagonal_in_inches}$

How To Use

Enter the display’s width in pixels.
Enter the display’s height in pixels.
Choose inches or centimeters for the diagonal size.
Enter the diagonal size.
Click “Calculate” to see the PPI.

What Is Pixels Per Inch (PPI)?

Pixels per inch (PPI) is a measure of how many pixels fit within a linear inch of a display. A higher PPI number means the display can show more detail in the same amount of space, resulting in sharper and clearer images. This calculation helps compare screens, from small mobile devices to large monitors, based on how finely they can render text, graphics, and other visual elements.

Examples

Example 1

Width: 1920 px
Height: 1080 px
Diagonal: 15 inches

Steps:
1920² = 3,686,400
1080² = 1,166,400
Sum = 3,686,400 + 1,166,400 = 4,852,800
√4,852,800 ≈ 2,202.91
PPI = 2,202.91 / 15 ≈ 146.86

The PPI is about 146.86.

Example 2

Width: 1280 px
Height: 720 px
Diagonal: 13 cm (about 5.12 inches, since 13 ÷ 2.54 ≈ 5.12)

Steps:
1280² = 1,638,400
720² = 518,400
Sum = 1,638,400 + 518,400 = 2,156,800
√2,156,800 ≈ 1,468.61
Diagonal: 13 cm = 5.12 in
PPI = 1,468.61 / 5.12 ≈ 286.08

The PPI is about 286.08.