Aspect Ratio Calculator (16:9, 4:3, 1:1, 21:9)
Calculate proportional screen and image dimensions for video, displays, and photos.
- 100% free
- Files stay on your device
- No sign-up, no watermark
Original Dimensions & Aspect Ratio
Proportional Resize Solver
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What is Aspect Ratio Calculator (16:9, 4:3, 1:1, 21:9)?
Size video canvases and graphic assets accurately. Select industry-standard aspect ratios (16:9 widescreen, 4:3 SD, 9:16 mobile, 21:9 ultrawide) or calculate custom proportions from existing pixel dimensions.
How to use Aspect Ratio Calculator (16:9, 4:3, 1:1, 21:9)
- 1
Add your file or input
Choose a supported file, drag it onto the upload area, or type/paste the data this tool works with.
- 2
Adjust the options
Pick the output format, quality, size or other settings the tool offers. Defaults work well for most files.
- 3
Process and download
Run the tool and save the result. Processing happens in your browser, so nothing is uploaded to a server.
Frequently asked questions
How do you find the simplified aspect ratio of any resolution?
The calculator finds the Greatest Common Divisor (GCD) using Euclid’s algorithm for both width and height (e.g. 1920x1080 divided by 120 yields exactly 16:9).
What is the standard aspect ratio for YouTube and modern monitors?
16:9 is the universal standard for YouTube, high-definition television, and desktop monitors, with common resolutions of 1920x1080 (1080p) and 3840x2160 (4K).
Can I scale an image to a specific width and calculate the exact height?
Yes! Enter your desired width and lock the ratio; the matching height is calculated instantly.
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