PPI Calculator

Enter your screen's resolution and diagonal size to get its pixel density (PPI), dot pitch, width and height. Pick a preset resolution or type your own.

Common sizes
Pixel density
108.79 PPI
42.83 pixels per cm
Dot pitch
0.2335 mm
Distance between pixel centers
Aspect ratio
16:9
Screen width
23.53 in
59.77 cm
Screen height
13.24 in
33.62 cm
Total pixels
3,686,400
3.69 megapixels

How to use the PPI calculator

  1. Pick a resolution preset, or type the width and height in pixels. Use the native resolution, not a scaled one. What Is My Screen Size? shows yours.
  2. Enter the diagonal size in inches, as listed in the specifications, or tap a common size.
  3. Read the pixel density, dot pitch and screen dimensions. They update as you type.

How PPI is calculated

Pixel density is the number of pixels along the diagonal divided by the diagonal length in inches. The diagonal in pixels comes from the Pythagorean theorem:

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

For a 27-inch 2560 × 1440 monitor, √(2560² + 1440²) = 2937.21 pixels, and 2937.21 ÷ 27 =108.79 PPI. The other results follow from the same numbers:

The calculator assumes square pixels, which nearly every modern screen has. It runs in your browser and nothing is sent anywhere.

PPI of common screen sizes

SizeResolutionPPIDot pitch
13.3″1920 × 1080165.60.153 mm
14″1920 × 1200161.70.157 mm
15.6″1920 × 1080141.20.180 mm
15.6″3840 × 2160282.40.090 mm
17.3″1920 × 1080127.30.199 mm
21.5″1920 × 1080102.50.248 mm
24″1920 × 108091.80.277 mm
24″2560 × 1440122.40.208 mm
27″1920 × 108081.60.311 mm
27″2560 × 1440108.80.233 mm
27″3840 × 2160163.20.156 mm
27″5120 × 2880217.60.117 mm
32″2560 × 144091.80.277 mm
32″3840 × 2160137.70.184 mm
34″3440 × 1440109.70.232 mm
49″5120 × 1440108.50.234 mm
55″3840 × 216080.10.317 mm
65″3840 × 216067.80.375 mm

Once you know your screen, check it for faults with the dead pixel test and thescreen bleed test, or measure its refresh rate with theFPS test.

Frequently asked questions

How do you calculate PPI?

Divide the diagonal resolution in pixels by the diagonal size in inches. The diagonal in pixels is the square root of width² + height². For a 27-inch 2560 × 1440 monitor that's 2937.21 ÷ 27 = 108.79 PPI.

What is a good PPI for a monitor?

It depends on how far away you sit: the farther you are, the less PPI you need for a sharp image. For comparison, a 24-inch 1080p monitor has 91.79 PPI, a 27-inch 1440p monitor has 108.79 PPI and a 27-inch 4K monitor has 163.18 PPI. Phones are held much closer, so they use far higher densities.

What is dot pitch?

Dot pitch is the distance between the centers of two neighboring pixels, usually given in millimeters. It's 25.4 divided by the PPI, because an inch is 25.4 mm. A smaller dot pitch means a denser, sharper screen.

Is PPI the same as DPI?

Not quite. PPI (pixels per inch) describes a screen, while DPI (dots per inch) describes printers and is also used for mouse sensitivity. People often use DPI for screens too, and for a display both terms mean the same thing.

Does a higher resolution always mean a higher PPI?

Only at the same screen size. A 32-inch 4K monitor has 137.68 PPI, which is lower than a 24-inch 1440p monitor at 122.38 PPI. Size and resolution together set the pixel density.

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