Common Presets
Scale by Width or Height
×
Find Missing Dimension
×
→
About this tool
Aspect Ratio Calculator
Aspect Ratio Calculator finds the ratio of any dimensions and scales them to a new size, so you can resize without distorting.
How to use it
- Enter a width and height to get the simplified ratio.
- Enter one known dimension to get the other at the same ratio.
- Read the scaled values.
How the ratio is reduced
A ratio is simplified by dividing both numbers by their greatest common divisor. 1920 and 1080 share a divisor of 120, which reduces to 16:9. That is why so many different resolutions describe the same shape.
Ratios worth recognising: 16:9 for video and most screens, 4:3 for older displays and many cameras, 1:1 for square social posts, 9:16 for vertical video, and 21:9 for ultrawide.
Worked example
Scaling a 16:9 asset down:
- Original1920 x 1080
- New width1280
Result: 720 for the height. Same shape, no letterboxing and no stretch.
When it helps
- Resizing an image or video without distorting it.
- Working out the height for a responsive embed at a given width.
- Checking whether an asset matches a required ratio before uploading.
- Converting a design between screen sizes.
Common mistakes
- Rounding one dimension and not the other, which introduces a slight stretch that is visible on straight lines.
- Assuming a ratio determines quality. 16:9 at 640x360 and at 3840x2160 are the same shape and very different images.
- Forgetting that cropping to a new ratio loses content, while scaling does not.
