Calculate proportional video dimensions and compare common aspect ratios.
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How to use Video Aspect Ratio Calculator
- Enter the original dimensions.
- Enter the desired width.
- Use the calculated height in your video editor and check its export requirements.
Example
1920 × 1080 reduces to 16:9. At width 1280, the proportional height is 720.
Method and formula
The greatest common divisor reduces original dimensions to an aspect ratio. Target height = target width × original height / original width, rounded to a whole pixel. The nearest common ratio is selected by comparing numeric width/height values with 16:9, 9:16, 1:1, 4:5 and 4:3.
Limits and supported input
This tool calculates dimensions; it does not edit, encode or export videos. Rounded dimensions can differ slightly from the exact ratio. Encoders may require even pixel sizes; check your editor. Input dimensions are whole numbers up to 1,000,000.
Privacy
This tool processes the input in your current browser tab. It does not upload your input or call a paid or remote API. Copying places text on your system clipboard; downloading saves a file on your device. Site hosting logs, analytics, ads, third-party embeds and other installed plugins are separate and can have their own data handling. JavaScript is required for the tool, while this explanation remains available without it.
Frequently asked questions
Can this convert a landscape video to vertical?
It can calculate sizes, but reframing and cropping need a video editor.
Why show a nearest ratio?
It is a numerical comparison, not an official platform recommendation.