Free Aspect Ratio Calculator
Find the missing width or height for any aspect ratio — perfect for resizing images, videos and layouts without distortion. Enter your original dimensions and a new size, and get the proportional value instantly.
How to Use
Enter the original width and height, then type a new width or height. The tool calculates the matching value and shows the simplified ratio. Common presets are one click away.
- Calculate the proportional width or height
- Shows the simplified ratio (e.g. 16:9)
- Popular presets for video, photos and social media
- Handles both landscape and portrait
- Instant recalculation
Common aspect ratios
16:9 is standard for HD video and YouTube. 4:3 is the classic TV and older camera format. 1:1 is square (Instagram), 9:16 is vertical (Stories, Reels, TikTok), and 21:9 is ultrawide cinema. Keeping the ratio when resizing prevents stretched or squashed images.
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