Enter a width and height to see the simplified ratio, or tap a common preset. Fill in a new width or height and the other side scales automatically to match.
- Type the original width and height (for example 1920 and 1080).
- Read the simplified ratio and decimal value below the fields.
- Type a new width or height to scale the other side to the same ratio, or tap a preset button.
Aspect Ratio Calculator
Enter an original width and height and the tool simplifies the ratio down to its lowest terms (for example 1920x1080 reduces to 16:9), showing the decimal value too.
Key features
- Original width and height number inputs, prefilled with 1920x1080 and editable to any dimensions.
- A new-width and new-height pair - type into either one and the matching side scales automatically along the same ratio.
- Seven one-tap presets - 16:9, 9:16, 4:3, 3:2, 1:1, 21:9, and 5:4 - fill the width and height for you.
When to use it
It is handy for resizing an image, video frame, or design canvas without distorting it - so a photo, export, or layout keeps its original proportions at the new size.
Privacy
The width and height you type stay in the browser - the ratio is reduced on this device, with no upload and no account.
Frequently Asked Questions
What does Aspect Ratio Calculator do?
It reduces a width and height to the simplest whole-number ratio (for example 3840x2160 reduces to 16:9) and can scale a new width or height to the same ratio.
Does it crop or resize my actual file?
No. This is a math-only calculator - it does not open, upload, or modify any image or video file. It just works out the numbers so you can resize elsewhere with the correct dimensions.
Why does the ratio look different from what I expected?
The tool reduces to the lowest whole-number terms using the greatest common divisor, so a slightly non-standard size (for example 1900x1069) may simplify to an unfamiliar ratio rather than snapping to the nearest common one like 16:9.