Aspect Ratio Calculator
Calculate aspect ratios, resize dimensions proportionally, and get CSS aspect-ratio values
16:9
1.7778
Common Ratios
Proportional Resize
aspect-ratio: 16 / 9;Aspect Ratio Calculator
Calculate aspect ratios, resize dimensions proportionally, and get CSS aspect-ratio values
Features
- Calculate aspect ratio from any width and height
- Proportional resize — enter new width or height to auto-calculate the other
- Common ratio presets (16:9, 4:3, 1:1, 21:9, etc.)
- Visual aspect ratio preview
- CSS aspect-ratio property output
- Swap dimensions with one click
- 100% client-side processing
How to use
- Enter width and height to calculate the aspect ratio.
- Or click a preset ratio button.
- Use the Proportional Resize section to find new dimensions.
- Copy the CSS aspect-ratio value for your stylesheets.
Tips & Best Practices
- Use 16:9 for standard video and presentations.
- Use 1:1 for social media profile pictures and Instagram posts.
- The CSS aspect-ratio property is supported in all modern browsers.
FAQ
What is an aspect ratio?
An aspect ratio is the proportional relationship between width and height. For example, 16:9 means for every 16 units of width, there are 9 units of height.
What aspect ratio is best for video?
16:9 is the standard for HD video and most screens. 21:9 is used for ultrawide/cinematic content. 9:16 is standard for vertical/mobile video.
How does proportional resize work?
Enter either a new width or new height, and the calculator will compute the other dimension to maintain the same aspect ratio — no stretching or distortion.