Aspect Ratio Calculator
Designing a banner, cutting a video or scaling a photo usually means keeping a ratio like 16:9 or 4:5. This calculator turns any width and height into its simplest ratio, and works out the missing side for any ratio you choose.
- Never uploaded
- Instant, no sign-up
- Works offline
About this tool
Type a size to see its ratio and orientation, or pick a ratio and a new width to get the matching height — perfect before you resize or crop.
How it works
- 1
Enter a width and height to see their ratio.
- 2
Or pick a ratio and type a new width.
- 3
Use the result in the resizer or cropper.
Features
- Simplest form1920×1080 becomes 16:9, 1080×1350 becomes 4:5.
- Missing dimensionGet the exact height for any width at a given ratio.
- Common presets1:1, 4:3, 3:2, 16:9, 21:9, 9:16, 4:5 and 2:3 in one tap.
- Private by designEverything runs on your device. No uploads, no account, no watermark, and EXIF/GPS data is stripped from the result.
Supported formats
No file needed — enter numbers. Results update as you type.
Frequently asked questions
How is the aspect ratio calculated?
Width and height are divided by their greatest common divisor, so 1920×1080 → 16:9.
What ratio is Instagram?
1:1 for square posts, 4:5 for portrait and 9:16 for stories and reels.
What if my ratio isn't a neat number?
You'll see the simplest whole-number form and the decimal ratio, e.g. 1.333:1.
Are my images uploaded to a server?
No. Files are decoded, processed and re-encoded by your browser using the canvas API and Web Workers. Nothing is sent to any server, and there is no account or storage. Closing the tab discards everything.
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