DPI Calculator (Pixel Density)

DPI (dots per inch) is a print term that counts ink dots per inch of paper. PPI (pixels per inch) is the screen equivalent, measuring how many pixels fit in one inch of a display. On monitors the two are used interchangeably because one pixel produces one visible dot. This calculator computes PPI from your screen's pixel resolution and physical diagonal size.

This calculator classifies 200-349 PPI as Retina-class (typical of high-density laptops and tablets) and 350 PPI and up as ultra-high (premium smartphones). Below 120 PPI, individual pixels are visible at normal viewing distance. Apple's original Retina pitch cited about 300 PPI for a phone held 10 to 12 inches away, since the exact threshold depends on how close you hold the device.

Physical size dilutes resolution. A 27-inch 4K (3840 x 2160) panel works out to about 163 PPI, which this calculator categorizes as standard. A 27-inch 1080p (1920 x 1080) panel is roughly 82 PPI, which falls in the low range. The pixel density difference is real, but Windows and macOS scale the interface by default, so the two screens can look similar until you inspect fine text or icons up close.

300 DPI is the standard for photo prints and magazine-quality output. 150 DPI is acceptable for posters viewed from several feet away. Large-format prints like banners and billboards can drop to 30-72 DPI because they are seen from far enough away that individual dots are not visible.

Check the spec sheet or the model number, for example a Dell U2723 is 27 inches. You can also measure the visible panel corner to corner with a tape measure, excluding the bezel. Most manufacturers publish the diagonal size on the product page or in the manual.