Aspect Ratio Calculator
How to Use
Enter width and height to calculate the aspect ratio. Use the presets to quickly fill in common ratios like 16:9 or 4:3. The resize calculator lets you find new dimensions that maintain the same proportions.
Aspect Ratios Explained
An aspect ratio describes the proportional relationship between width and height. 16:9 is the standard for HD/4K video and most monitors. 4:3 was the classic TV and early computer standard. 21:9 is used for ultrawide displays and cinema. 1:1 is square, common in social media. 9:16 is vertical video for mobile platforms like TikTok and Instagram Reels.
Use Cases
- Responsive web design: determine ratios for the CSS aspect-ratio property and prevent layout shifts
- Video editing: calculate crop dimensions when converting footage to 16:9 or 9:16
- Image cropping: find optimal dimensions that maintain proportions when resizing for social media
- Social media sizing: check recommended ratios for Instagram (1:1, 4:5), YouTube (16:9), X/Twitter headers (3:1), and more
- Print design: calculate image ratios for paper sizes like A4 (approximately 1:1.414) or B5
The CSS aspect-ratio Property
The CSS aspect-ratio property lets you define the preferred width-to-height ratio of an element. For example, 'aspect-ratio: 16 / 9;' automatically calculates the height based on width. It replaces the legacy padding-top hack (padding-top: 56.25%) for responsive video embeds and card layouts. You can copy the ratio calculated by this tool and apply it directly in your CSS.
Privacy
All calculations happen entirely in your browser. No data is sent to a server, stored, or logged.