Design · Free
Aspect Ratio Calculator
Find the aspect ratio of any width and height (1920 × 1080 = 16:9), or the missing side when you resize an image or video to a ratio.
Ratio of a size
16:9 · 1.7778:1
Widescreen HD (YouTube, TVs, monitors)
Resize to a ratio
1,280 × 720 px
About this tool
Type a width and a height in pixels and get the simplest whole-number ratio — 1920 × 1080 is 16:9, 1080 × 1920 is 9:16, 2560 × 1080 is 64:27 (the panels sold as "21:9") — together with the ratio as a single decimal, which is how cinema formats such as 2.39:1 are usually quoted. Well-known ratios are named, so you can see at a glance whether a size suits YouTube, Instagram, a phone screen or an ultrawide monitor.
The second panel works the other way round: pick a ratio (or type any, including decimals like 2.39:1), then enter the new width or the new height, and the tool gives the other side rounded to whole pixels. It is the quick answer to "what height keeps 16:9 at 1280 pixels wide?" when you export a video, crop a thumbnail or size an embed.
Everything is calculated in your browser; nothing you type is sent anywhere.
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