HTMLAspect Ratio Calculator
Solve for a missing width or height given an aspect ratio, compare two resolutions, and find the nearest named aspect ratio (16:9, 4:3, 21:9, 1:1, 9:16, etc.). Useful for sizing images, video thumbnails, responsive layouts, and print formats.
Ctrl+Enter to run | Ctrl+K to switch tools | Recent button shows input history
Repeating this work? Turn this kind of browser utility into an API batch, MCP prompt, extension workflow, or shared team recipe.
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How do I resize an image while keeping its aspect ratio?
Enter the original width and height, then enter only the new width (or height) you want. The tool calculates the other dimension for you. This prevents distortion.
What are standard aspect ratios?
Common ones: 16:9 (HD video, YouTube), 4:3 (traditional TV, iPad), 1:1 (Instagram square), 21:9 (ultrawide), 9:16 (TikTok/Reels portrait), 3:2 (DSLR / 35mm film).