Screen Tools
Enter a diagonal, width, or height plus the aspect ratio to get every display dimension — in inches, cm, mm, feet, and meters.
All calculations run locally in your browser. Nothing is uploaded.
Selecting a resolution automatically sets its aspect ratio.
Pick a resolution or aspect ratio, enter the diagonal you know, and press Calculate.
When you shop for a TV, monitor, or laptop, the screen size is advertised as a diagonal measurement — a “55-inch TV” or a “27-inch monitor”. That single number does not tell you the actual width and height of the display. Those depend on the screen's aspect ratio, the shape of the rectangle. A 55-inch 16:9 TV and a 55-inch 21:9 ultrawide monitor end up with very different widths, heights, and total viewing areas.
What is aspect ratio? The aspect ratio describes the shape of a screen: 16:9 means the screen is 16 units wide for every 9 units tall. It is the most common ratio today, used by 4K TVs, Full HD monitors, and most laptops. Older TVs and some tablets use 4:3, which is closer to a square. Ultrawide monitors use 21:9 or even 32:9 for a much wider field of view, while 3:2 (Surface-style panels) and 16:10 (productivity laptops) sit somewhere in between.
How the dimensions are calculated. Diagonal, width, and height form a right triangle, so the Pythagorean theorem connects them. Given a ratio w:h and the diagonal:
Two screens with the same diagonal but different ratios therefore have different widths, heights, and areas — a 55-inch 16:9 panel has roughly 1,292 square inches of viewing area, while a 55-inch 4:3 display offers about 1,452 square inches because its shape is less stretched.
Why screen size matters. Knowing the true width and height helps you check whether a TV fits the wall before mounting it, whether a monitor fits your desk, and how two displays really compare. Area is the fair comparison metric: a 65-inch TV has almost 40% more viewing area than a 55-inch one — not just 18% more as the diagonal numbers suggest — because area scales with the square of the diagonal.
Common screen sizes at a glance. Most TVs sold today run from 43 to 85 inches in 16:9. Monitors are commonly 24, 27, or 32 inches; laptops 13 to 17 inches. A 34-inch 21:9 ultrawide offers a wider workspace than a 34-inch 16:9 panel but less height, and a 49-inch 32:9 super ultrawide is essentially two 27-inch monitors side by side. Remember the results describe the panel itself — bezels add a few millimeters per side.
Units of measurement. Screens are listed in inches almost everywhere, but some regions and product sheets use centimeters or millimeters. One inch equals 2.54 cm or 25.4 mm, and the conversion table in the results also shows feet and meters for wall-mounting and desk planning.
A 34-inch 21:9 panel is about 31.3 in (79.4 cm) wide but only 13.4 in tall. Compare both numbers with your desk space before buying.
A 65-inch 16:9 TV measures roughly 56.7 × 31.9 in (144 × 81 cm). Use the conversion table to check the wall space in your preferred units.
Aim for roughly 110 PPI or more at your normal viewing distance. Select a resolution preset to see the PPI before ordering.
Convert Roman numerals to numbers and back (1–3999) with breakdowns, chart, year conversion, validator and generator.
Describe what you want to match and get a working regular expression with explanations and examples.
Test regular expressions against sample text with match highlighting, capture groups, and explanations.
Complete regular expression syntax reference with examples for every major construct.
Looking for something else? Browse all tools