Calculate Ratios for Responsive Design
Find the correct height for responsive images and containers given a fixed width and target ratio.
Common dimensions
Responsive tips
Responsive containers need a known aspect ratio to maintain layout. Enter your container width and ratio to get the exact height needed.
The CSS padding-top trick: padding-top: 56.25% gives a 16:9 container. Calculate your ratio as (h/w × 100)% to get the right percentage.
Modern CSS: aspect-ratio: 16/9 works in all modern browsers. Use the simplified ratio output from this tool directly in CSS.
For <img> tags, always specify width and height attributes matching the image's natural ratio. Prevents layout shift (CLS) as images load.
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