Aspect Ratio Calculator
Pick a preset ratio or enter your own, then type either a width or a height to get the matching dimension.
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Video Resolutions and Aspect Ratios Explained
Aspect ratio describes the proportional relationship between width and height. 16:9 is the standard for widescreen video: 1280×720 (720p), 1920×1080 (1080p), 2560×1440 (1440p) and 3840×2160 (4K UHD) all share it, which is why footage scales between them without cropping.
Vertical 9:16 is the native frame for mobile-first platforms — 1080×1920 is the safe delivery size for stories, reels and shorts. Square 1:1 (1080×1080) still performs well in feeds where vertical space is limited, while 4:3 (1600×1200) survives in photography, presentation decks and older sensor formats. Cinematic 21:9 (2560×1080) is used for letterboxed trailers.
When resizing, always change both dimensions together. Scaling only one axis stretches faces and text; scaling both and then cropping to the target frame keeps the subject proportional. Export at the platform's native resolution instead of relying on its re-encoder, which usually costs visible detail.
Frequently asked questions
Multiply the known dimension by the ratio: height = width × (ratio height ÷ ratio width). The calculator does this for you as you type.