Aspect Ratio Calculator
Free aspect ratio calculator for CSS aspect-ratio property. Enter 16:9 or pixel dimensions to get simplified ratios, CSS declarations, and responsive sizing, all in your browser, no upload.
Runs locally in your browser. Your input is not uploaded to DevToolMate servers.
Developer Quick Tips
- Enter aspect ratio as 16:9, 16/9, or 16x9 to instantly generate CSS aspect-ratio syntax and padding-top hack percentages for responsive embeds.
- Use pixel width and height mode to simplify large dimensions like 1920×1080 into the smallest whole-number ratio (16:9) with one click.
- Copy ready-to-paste CSS declarations directly into your stylesheets; all calculations run locally in your browser with no server upload.
- Calculate responsive embed sizing by entering your desired width and getting the proportional height for video, iframe, or image containers.
- Generate padding-top percentage values for legacy aspect-ratio hacks on older browsers that don't support the CSS aspect-ratio property.
Frequently asked questions
Does the aspect ratio calculator upload my data?
No. Aspect Ratio Calculator runs entirely in your browser using local processing. Your input is never uploaded to DevToolMate servers or any external service.
Is this aspect ratio calculator free?
Yes, completely free. No account, login, or payment required. All calculations happen on your device, and you can use it as many times as you need.
How do I use the aspect ratio calculator for CSS?
Enter a ratio like 16:9 or pixel dimensions (e.g., 1920×1080). The tool outputs a ready-to-copy CSS aspect-ratio declaration (e.g., aspect-ratio: 16 / 9;) and a decimal ratio for use in calculations.
What is the padding-top hack for aspect ratio?
The padding-top hack is a legacy technique for maintaining aspect ratio on responsive embeds before CSS aspect-ratio property support. The calculator generates the percentage value (e.g., 56.25% for 16:9) to use with padding-top in your CSS.
Can I calculate aspect ratio from pixel dimensions?
Yes. Switch to Size mode, enter width and height in pixels, and the calculator simplifies them to the smallest whole-number ratio and shows the CSS aspect-ratio property syntax.
Will my input persist after I close the tab?
No. Input stays in memory only while the page is open. Closing the tab clears all tool input. Your browser theme preference is stored locally but is separate from tool data.
What formats does the aspect ratio calculator accept?
Ratio mode accepts 16:9, 16/9, or 16x9 formats. Size mode accepts positive pixel numbers for width and height. The tool validates input and reports clear errors for malformed entries.
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