Calculate Image Dimensions for Web
Ensure images fit their containers perfectly — find the right width and height for any layout.
Common dimensions
Web tips
If your CSS container is 800px wide and you want a 16:9 image, calculate the height: 800 / 16 × 9 = 450px. This tool does that for you.
Using aspect-ratio CSS? The tool shows the simplified ratio (e.g. 8:5) which you can use directly in aspect-ratio: 8/5 in CSS.
For responsive images, calculate at your largest breakpoint, then CSS handles the scaling. The ratio stays the same at all widths.
Always specify width and height attributes on <img> tags (matching the image's natural ratio) to prevent Cumulative Layout Shift (CLS).
工作原理
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