HTML Link & Heading Extractor
About CSS Aspect Ratio Generator
The CSS `aspect-ratio` Rule & Padding-Bottom Fallback Generator creates modern `aspect-ratio: width / height` declarations and legacy padding-bottom percentage hacks (`(height / width) * 100%`) for responsive video embeds, image containers, and responsive cards.
How to Use CSS Aspect Ratio Generator
Step 1
Select a common preset ratio or enter custom width and height dimensions in pixels.
Step 2
Review the modern CSS `aspect-ratio` and legacy padding fallback code.
Step 3
Click "Copy CSS".
Practical Use Cases for CSS Aspect Ratio Generator
Preventing Cumulative Layout Shift (CLS) on Images & Videos
Enforce `aspect-ratio: 16 / 9` on responsive video wrappers and image containers to reserve vertical layout space before media assets finish loading.
Building Responsive Video & Banner Components
Generate standard aspect ratios for 16:9 widescreen video, 4:3 standard, 1:1 square, 9:16 vertical TikTok/Reels, and 21:9 ultrawide banners.
Input & Output Examples
Generating 16:9 Aspect Ratio with Legacy Fallback
Ratio: `16:9` (1920x1080)
Modern CSS: `aspect-ratio: 16 / 9;` | Legacy Fallback: `padding-top: 56.25%; /* (9/16)*100 */`
Key Features & Performance
- ✓Presets: 16:9 (Widescreen), 4:3 (Standard), 1:1 (Square), 9:16 (Stories/Reels), 21:9 (Ultrawide), 3:2 (Photography), 2:1 (Social Header).
- ✓Calculates exact reduced aspect ratio fractions from custom pixel dimensions (e.g. `1440x900` $\\rightarrow$ `8:5`).
- ✓Generates both modern `aspect-ratio` CSS and responsive padding-top intrinsic ratio wrappers.
- ✓100% Client-Side memory execution.
- ✓1-Click Copy CSS rule.
Key Terminology & Definitions
`aspect-ratio` CSS Property
A native CSS property that sets a preferred aspect ratio for the box, automatically calculating the other dimension when either width or height is defined.
Cumulative Layout Shift (CLS)
A Core Web Vital metric measuring visual stability; reserving aspect ratio space prevents unexpected layout jumps as images download.