Aspect Ratio Calculator

The calculator answers two common questions at once. What ratio is this, and what size do I need to keep it? Type a width and height, say 1920 by 1080, and it returns 16:9, 1.7778, its common name and orientation, plus the CSS line aspect-ratio: 16 / 9 for anyone building a layout. In the resize section, set a new width and it works out the height, so 16:9 at 1280 wide gives 720.

A live preview frame shows the shape, and you can switch it between an image and a video placeholder. That makes it easier to judge whether 4:5 or 9:16 suits a post before exporting anything.

One click loads common ratios, each labeled with where it's used: 16:9 for YouTube and slides, 9:16 for TikTok, Reels and Shorts, 4:5 for Instagram portrait posts, 1:1 for avatars and thumbnails, 3:2 for DSLR photos, 21:9 for ultrawide and cinema, and 32:9 for super-wide dual-monitor setups. A quick reference list pairs standard pixel sizes with their ratios, such as 1080 by 1350 for a 4:5 post or 3440 by 1440 for a 21:9 monitor.

If you don't know an image's dimensions, choose a JPG, PNG, WebP or GIF and the page reads its width and height. The file stays on your device. There's no account, and the privacy page says the site currently runs no analytics or advertising scripts. It's a small, focused tool for designers, video editors and social media managers who resize things all day.