PPI Calculator
Work out pixels per inch two ways: from an image and the size you intend to print it, or from a screen resolution and its diagonal measurement. Both give you the true pixel density rather than a tagged value.
Leave the height blank to work from the width alone.
How to calculate PPI
For a printed image, divide the pixel count by the physical size: PPI = pixels ÷ inches. A 2550 pixel wide file printed 8.5 inches across is 2550 ÷ 8.5 = 300 PPI.
For a screen, the width and height are combined first because the diagonal is what manufacturers quote: PPI = √(width² + height²) ÷ diagonal in inches. A 27-inch 2560 × 1440 monitor works out at about 109 PPI.
Worked with the values in the calculator above
DPI across width = 2,550 px ÷ 8.5 in = 300 DPI
DPI across height = 3,300 px ÷ 11 in = 300 DPI
usable density = the smaller of the two = 300 DPIPPI = √(2,560² + 1,440²) ÷ 27 in = 108.79 PPI
1 px = 1 ÷ 108.79 PPI = 0.00919 in What counts as a good pixel density?
Above roughly 300 PPI a print is indistinguishable from continuous tone at reading distance. Screens are judged differently because you sit further away: 90 to 110 PPI is a standard desktop monitor, 130 to 200 PPI is a high-density laptop, and anything above 200 PPI is marketed as retina-class.
Pixel density and resolution are not the same thing. A 4K panel at 55 inches has a far lower PPI than a 4K panel at 27 inches, even though both hold the same number of pixels.
At the density above
One inch square at 96 PPI
96 × 96 = 9,216 pixels fill this square.
Reference table
| Display | Resolution | Diagonal | PPI |
|---|---|---|---|
| 24" monitor | 1920 × 1080 | 24 in | 91.8 |
| 27" monitor | 2560 × 1440 | 27 in | 108.8 |
| 27" 4K monitor | 3840 × 2160 | 27 in | 163.2 |
| 32" 4K monitor | 3840 × 2160 | 32 in | 137.7 |
| 15.6" laptop | 1920 × 1080 | 15.6 in | 141.2 |
| MacBook Pro 14.2" | 3024 × 1964 | 14.2 in | 253.9 |
| iPad Pro 12.9" | 2048 × 2732 | 12.9 in | 264.7 |
| iPhone 6.1" | 1179 × 2556 | 6.1 in | 460.0 |
| 55" 4K TV | 3840 × 2160 | 55 in | 80.1 |
Frequently asked questions
What PPI is a 6.1-inch phone at 2556 × 1179?
About 461. √(2556² + 1179²) is 2,815 pixels on the diagonal, and 2,815 ÷ 6.1 is 461 — roughly four times a desktop monitor, which is why phone text looks sharper at the same nominal size.
How do I calculate pixel density?
Pixel density and PPI are the same measurement. Take the pixels along one edge, divide by that edge in inches, and the result is the density in pixels per inch.
How many pixels per inch is high resolution?
For print, 300 PPI is the professional standard and anything below 150 PPI looks soft in the hand. For screens, above 200 PPI is considered high resolution at normal viewing distance.
Is PPI the same as DPI?
In everyday use they are interchangeable. Strictly, PPI counts pixels in an image or on a display while DPI counts the ink dots a printer lays down, and a printer may use several dots per pixel.
What is my screen PPI?
Switch the calculator above to the screen method, enter your resolution and the diagonal size from the spec sheet, and it reports the true density along with the dot pitch in millimetres.