The Aspect Ratio Calculator helps you calculate, maintain, and convert aspect ratios for screens, images, videos, and UI components. Given any two dimensions (width and height), it instantly calculates the simplified ratio (such as 16:9 or 4:3) and the equivalent dimensions at any target size. It works in both directions: you can enter a ratio to calculate pixel dimensions, or enter pixel dimensions to find the ratio. Common preset ratios are included for quick selection: 16:9 (widescreen video and monitors), 4:3 (traditional TV and tablet), 1:1 (square social media), 9:16 (vertical mobile video), and 21:9 (ultrawide). This tool is useful for web developers setting responsive image dimensions, video editors calculating output resolution, UI designers working with fixed-ratio containers, and photographers cropping images to specific print sizes. The tool runs entirely in your browser and requires no account or installation. To extend the output further, Flexbox Generator can generate CSS Flexbox layout code, SVG Optimizer can optimize and clean up SVG file markup, and Favicon Generator can generate favicons in multiple sizes from any image.
Maintaining the correct aspect ratio prevents the two most common image problems on the web: squishing (where an image appears narrower or shorter than intended) and stretching (where it appears wider or taller). Both occur when width and height are set independently without preserving the original ratio. This calculator makes it trivial to find the missing dimension: enter the known dimension and the desired ratio and the other dimension is calculated immediately. For responsive web design, this is especially useful when converting a fixed-size design to percentage-based or fluid dimensions. For video production, standard broadcast and streaming ratios each have specific requirements: 1920x1080 for 16:9 HD, 3840x2160 for 16:9 4K, 1080x1920 for 9:16 vertical. Social media platforms also enforce specific ratios: Instagram Feed accepts 1:1 to 4:5, Story and Reel use 9:16, Twitter/X cards use 16:9. Cropping to the wrong ratio causes auto-cropping by the platform, often removing important parts of the image. The greatest common divisor reduction used internally ensures that ratios like 1920:1080 simplify cleanly to 16:9 rather than leaving large numbers that obscure the underlying relationship.