PPI Calculator

How to use

1. 1Pick a common display preset, or type your own resolution as width in pixels and height in pixels.
2. 2Leave the mode on Pixel density, then enter the screen diagonal in inches, the corner to corner size used to describe a monitor or TV.
3. 3Read the PPI result along with dot pitch, total pixels, megapixels, physical size, and a density grade.
4. 4Use Swap if you entered width and height the wrong way round, or tap Clear to start over.
5. 5Switch to Screen size for a target PPI, enter a target density, and read the diagonal a panel would need at that resolution.
6. 6Copy any single value or the summary. Everything is calculated in your browser with no upload.

About this tool

PPI Calculator works out the pixel density of a screen from two numbers anyone can find on a spec sheet: the resolution in pixels and the diagonal size in inches. PPI means pixels per inch, the count of pixels packed into one inch of a display, and it is the figure that decides whether a screen looks crisp or whether you can see individual pixels up close. The math is plain geometry. A display that is W pixels wide and H pixels tall has a diagonal of sqrt(W^2 + H^2) pixels, and spreading that pixel diagonal over a physical diagonal of D inches gives PPI = sqrt(W^2 + H^2) / D. From that single result the tool derives everything else a display calculator is expected to report. Dot pitch, the centre to centre distance between neighbouring pixels, is 25.4 divided by the PPI because there are 25.4 millimetres in an inch. The physical width and height in inches and centimetres come from dividing each pixel count by the PPI, which is exactly why two screens at the same resolution but different sizes have different densities: a 1080p panel at 24 inches is sharper than the same 1080p panel at 32 inches. The tool also reports total pixels and megapixels and the full diagonal resolution in pixels, then assigns a descriptive density band, from standard density through high density and retina class up to ultra high density, with a clear reminder that perceived sharpness depends on viewing distance and not on PPI alone. A wall mounted television seen from across a room can look perfectly crisp at a low PPI, while a phone held at reading distance needs a far higher one to hide its pixels. A second mode answers the reverse question people search for just as often: given a resolution and a target PPI, how large or small does the diagonal need to be? That is the same formula rearranged to D = sqrt(W^2 + H^2) / target PPI, which is handy when choosing a monitor size that will hit a density you like, or checking whether a given panel can reach retina class. Presets load common displays, from 1080p and 1440p and 4K monitors at popular sizes to a typical laptop, phone, and tablet, so you can confirm the tool against hardware you already know, and a reference table lists the approximate density of those familiar screens. A note worth keeping in mind: PPI describes pixels per inch on a screen, while DPI describes dots per inch in printing, so the two are not interchangeable even though people often say DPI when they mean PPI. For sizing an image for print at a chosen DPI, the DPI Calculator in the related tools is the right tool. Everything here is computed locally in your browser using simple arithmetic. The resolution, diagonal, and target values you type are never uploaded, never logged, and never leave your device.

Free to use. Works in your browser. No signup, no login.