Screen Ratio Calculator

A screen ratio describes the proportional relationship between a display's width and height. It does not specify the physical size or total resolution by itself. A 1920 by 1080 monitor and a 3840 by 2160 television both reduce to 16:9, even though one contains four times as many pixels. This calculator divides both pixel dimensions by their greatest common divisor to show the cleanest whole-number ratio, while also reporting the width-to-height decimal. Aspect ratio matters whenever content must fit a screen. Video editors use it to prevent unwanted letterboxing or cropping, designers use it when preparing responsive layouts, and gamers compare it when choosing standard, ultrawide, or super-ultrawide monitors. Common ratios include 4:3 for older television and computer displays, 16:9 for modern video, 16:10 for productivity monitors, and 21:9 for ultrawide screens. Some marketed ratios are approximate because the exact pixel dimensions reduce to a less familiar pair. The diagonal resolution is the straight-line pixel distance between opposite corners. It is calculated with the Pythagorean theorem: the square root of width squared plus height squared. If you also enter the physical diagonal in inches, the calculator divides diagonal pixels by diagonal inches to obtain pixels per inch, or PPI. PPI measures pixel density rather than resolution alone. A smaller display can therefore look sharper than a larger display using the same number of pixels. Use the native pixel resolution reported by the device rather than a scaled desktop setting for the most meaningful result. Width and height can be entered in either landscape or portrait order; rotating a display reverses the ratio but does not change its diagonal pixel count or density. Fractional dimensions are accepted, although screen resolutions are normally whole pixels. The optional diagonal should describe the viewable panel rather than the outside dimensions of the case. Knowing the exact screen ratio helps you select compatible wallpapers, export video at the correct frame shape, compare monitors, and estimate how efficiently content will use the available panel. Combined with PPI, it also provides a practical way to compare apparent sharpness across phones, laptops, monitors, projectors, and televisions.