Screen Size Calculator

How to use

1. 1Enter the diagonal screen size (the way TVs and monitors are sold). Switch the unit toggle to inches or centimetres to match what the manufacturer published.
2. 2Pick an aspect ratio from the preset grid, or type a custom width-to-height ratio. The default 16:9 covers most TVs and modern monitors.
3. 3Read the physical width, height, surface area, and reduced aspect ratio in the result panel. Inches and centimetres are shown side by side.
4. 4Optionally enter the screen resolution (or pick a preset) to also see PPI, dot pitch in millimetres, the total pixel count, and a density grade.
5. 5Click Copy summary to grab a one-line description of the screen dimensions for a spec sheet, a chat message, or a purchase note.

About this tool

Screen Size Calculator turns a diagonal screen measurement and an aspect ratio into the actual physical width, height, surface area, and (when a pixel resolution is given) the pixel density of any display. Type the diagonal in inches or centimetres, pick an aspect ratio from the preset row (16:9 covers most TVs and monitors, 16:10 covers many laptops, 21:9 and 32:9 cover ultrawides, 4:3 and 5:4 cover older displays, 3:2 covers Surface devices, 1:1 covers square panels, 9:16 and 9:19.5 cover vertical phones), or type a custom width-to-height ratio. The width and height are computed from a Pythagorean decomposition of the diagonal, so the numbers are mathematically exact: width = (w / sqrt(w² + h²)) × diagonal, height = (h / sqrt(w² + h²)) × diagonal. Results are presented in inches and centimetres side by side so you can compare them against a tape measure, a desk depth, a wall plan, or a packing box without doing the unit conversion yourself. The surface area is also computed (handy when comparing two displays that have different aspect ratios but the same diagonal, where the wider screen actually shows less area), and the simplified aspect ratio is shown alongside the decimal ratio in case your design tool, mounting bracket, or specification sheet asks for that form. Add a resolution and the tool also reports PPI (pixels per inch), dot pitch in millimetres (the distance between adjacent pixel centres, lower is sharper), the total pixel count in megapixels, and a density grade so you can compare a 24-inch 1080p panel against a 27-inch 1440p panel against a 32-inch 4K panel at a glance. Presets for common diagonals (6.1" and 6.7" phones, 11" tablets, 13.3" to 16" laptops, 24" to 34" monitors including ultrawides, 43" to 85" TVs) and common resolutions (Full HD, QHD, 4K, 8K, ultrawide, super-ultrawide, WUXGA, native MacBook Pro resolutions) make it fast to test a candidate purchase or a desk layout. Useful when shopping for a monitor or TV and planning how it will fit on your desk or wall, comparing two displays where the diagonal is the same but the aspect ratio is different (21:9 ultrawides really do feel smaller than 16:9 panels of the same diagonal), planning a TV mounting position based on physical height not diagonal, sizing AR or VR canvases against a real-world panel, picking a tablet that matches your bag dimensions, or any moment when the manufacturer only published the diagonal and you need the actual width and height. All calculations run locally in your browser. Nothing is uploaded.

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