Aspect Ratio Calculator
Scale dimensions without distortion
100% Private & In-Browser
Processed locally using client-side JavaScript. Your files and data never touch any server.
Instant & Unlimited
No registration, no waiting queues, and no limits on file conversions or generations.
What is Aspect Ratio Calculator?
The Aspect Ratio Calculator solves the missing dimension of any ratio: enter your ratio (16:9, 4:3, 21:9, or a custom one) plus either the width or the height, and it returns the matching other side. It also simplifies pixel dimensions down to their simplest ratio form.
How to use Aspect Ratio Calculator
Enter the target ratio, or paste existing dimensions to detect it.
Enter the one dimension you already know — width or height.
The tool solves the proportional second dimension instantly.
Use the simplified-ratio output for specs, CSS, or documentation.
- Solve for width or height against any custom ratio
- Automatic ratio simplification from raw pixel dimensions
- Common presets (16:9, 4:3, 1:1, 21:9) plus fully custom input
- Instant, private, free — computed on your device
- Resizing images and video thumbnails without distortion.
- Specifying responsive embeds and canvas sizes in CSS or design files.
- Checking whether two screens or prints share the same shape ratio.
Frequently Asked Questions
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