Screen Size Calculator

Screen sizes are normally advertised by their diagonal measurement, but a diagonal alone does not reveal the panel's width or height. A 24-inch widescreen monitor is much wider and shorter than a 24-inch display with an older 4:3 shape. This screen size calculator combines pixel width, pixel height, and diagonal inches to recover the physical dimensions while preserving the display's exact aspect ratio. The calculation starts with the diagonal pixel length, found from the square root of horizontal pixels squared plus vertical pixels squared. Dividing the physical diagonal by that pixel diagonal produces the physical size of one pixel. Multiplying that scale by the horizontal and vertical resolutions gives screen width and height in inches. The calculator also converts those measurements to centimeters, multiplies width by height for viewable area, and divides diagonal pixels by diagonal inches for pixels per inch. Pixel density is useful when comparing displays that have different sizes or resolutions. A 4K phone and a 4K television contain similar pixel counts, but the phone packs them into a much smaller panel and therefore has far higher PPI. Higher density can make text and images appear smoother, although viewing distance, eyesight, panel quality, and operating-system scaling also influence perceived sharpness. Television viewers sit farther away than laptop users, so a lower PPI can still look detailed. Enter the panel's native resolution rather than the scaled resolution shown by an operating system. Manufacturers usually quote the diagonal of the active display area, though bezels and rounded corners can introduce small differences from measurements taken with a tape. The output assumes square pixels, which is standard for modern monitors, televisions, tablets, and phones. Unusual video formats with non-square pixels require additional correction and are outside this calculator's scope. Physical dimensions help with desk planning, wall mounting, multi-monitor layouts, presentation design, and comparisons between differently shaped screens. Viewable area can reveal why a modest increase in diagonal produces a much larger panel: area grows with the square of linear size. By showing dimensions, area, aspect relationship, and PPI together, this calculator gives a more complete description than an advertised diagonal or resolution can provide alone.