PPI Calculator (Pixels per Inch). Enter your screen's width in pixels, height in pixels, and diagonal size to calculate its PPI (pixels per inch). Your PPI Calculator returns pixel density, dot pitch, diagonal resolution in pixels, and total megapixels — giving you a complete picture of your display's sharpness. Also try the calculate Estimated Download Time, Total Seconds & Effective Speed — Download Time.
PPI stands for pixels per inch and measures how densely pixels are packed on a screen. A higher PPI means sharper, crisper images because more pixels are packed into each inch. For example, a smartphone with 400 PPI will look noticeably sharper than a monitor at 100 PPI when viewed at the same distance. See also our calculate Lowest Monthly Cost, AWS S3 Monthly Cost & Google Cloud Storage Monthly Cost — Cloud Storage Cost.
PPI is calculated in two steps. First, use the Pythagorean theorem to find the diagonal resolution in pixels: diagonal_px = √(width² + height²). Then divide that diagonal pixel count by the physical diagonal size in inches: PPI = diagonal_px ÷ diagonal_inches.
Dot pitch is the physical distance between the centers of adjacent pixels, measured in millimeters. It is the inverse of PPI — a lower dot pitch means a higher PPI and a sharper display. It is calculated as: dot pitch (mm) = (diagonal in inches / diagonal in pixels) × 25.4.
PPI² is the number of pixels contained in one square inch of screen area, calculated by squaring the PPI value. It gives you a measure of total pixel density in two dimensions rather than just along a line, which can be useful when comparing display sharpness more rigorously.
For desktop monitors viewed at arm's length, 90–110 PPI is standard, while 150+ PPI is considered high-density. Laptops typically benefit from 150–220 PPI. Smartphones viewed close up generally need 300+ PPI to appear sharp, and 400+ PPI is considered retina-quality for handheld devices.
Your screen resolution (width × height in pixels) can be found in your operating system's display settings. The diagonal size is the physical measurement from one corner of the screen to the opposite corner and is typically listed in the device specifications or printed on the product box.
Yes — select 'Centimeters' from the Diagonal Units dropdown and enter your diagonal measurement in cm. The calculator automatically converts the value to inches for the PPI calculation and also returns the pixels per centimeter (PPcm) result.
Aspect ratio is the proportional relationship between a screen's width and height (e.g. 16:9). It is derived from the pixel resolution — a 1920×1080 display has a 16:9 aspect ratio. Aspect ratio affects how content appears on screen but does not directly determine PPI, which also depends on the physical screen size. You might also find our IP Subnet Calculator useful.