PPI Calculator
px
px
in
Pixel Density91.79 PPI
Dot Pitch0.2767 mm
Resolution2.07 MP
The PPI Calculator reports how densely packed the pixels on a screen are, measured in pixels per inch. Enter the display horizontal and vertical resolution along with its diagonal size in inches, and it finds the diagonal pixel count, divides by the physical diagonal, and returns the density. Higher PPI generally means sharper text and images because individual pixels become harder to see.
Formula
PPI = √(widthPx² + heightPx²) / diagonalInches
- widthPx
- Horizontal resolution in pixels
- heightPx
- Vertical resolution in pixels
- diagonalInches
- Physical diagonal size of the screen in inches
How it works
- Enter the screen horizontal and vertical resolution in pixels (for example 1920 by 1080).
- Enter the diagonal screen size in inches as quoted by the manufacturer (for example 24).
- The calculator finds the diagonal in pixels with the Pythagorean theorem, divides it by the diagonal in inches for PPI, and also reports the dot pitch in millimetres and the total megapixels.
Worked example
A 24-inch monitor running 1920 × 1080.
- Diagonal pixels = √(1920² + 1080²) = √(3,686,400 + 1,166,400) = 2202.91.
- PPI = 2202.91 ÷ 24 = 91.79.
- Dot pitch = 25.4 ÷ 91.79 = 0.2767 mm.
About 91.79 PPI with a 0.2767 mm dot pitch.
Frequently asked questions
- What is a good PPI for a monitor?
- Desktop monitors around 90 to 110 PPI look crisp at normal viewing distance. Phones and tablets are viewed closer, so they target 300 PPI or more to keep pixels invisible.
- What is the difference between PPI and DPI?
- PPI describes pixel density on a screen, while DPI describes ink dots per inch on a printer. They are often used interchangeably but refer to displays and printing respectively.
- What is dot pitch?
- Dot pitch is the distance between the centres of adjacent pixels, in millimetres. It is the reciprocal of PPI scaled by 25.4, so a higher PPI gives a smaller dot pitch and a finer image.
- Why does a larger screen with the same resolution have lower PPI?
- The same number of pixels spread over a bigger diagonal means each pixel is physically larger, so density falls. That is why a 27-inch 1080p panel looks softer than a 24-inch one at the same resolution.