What does this tool do?
Aspect Ratio Calculator finds the missing side length while keeping a given width-to-height ratio. You enter the ratio and one known dimension, and the tool instantly computes the other. It is handy for designers resizing images, video editors, and anyone working with screen resolutions.
How to use it
- Enter your values into the fields.
- The result is calculated instantly.
- Read or copy the result.
When it helps
If you want to scale an image down from 1920x1080 to a width of 1280 pixels, you instantly get the correct height (720) without distorting the ratio. The same logic applies to video exports, thumbnail generation, and social media graphics. It also saves time when scaling banner ads, presentation slides, and print layouts at a fixed ratio, removing the guesswork and eyeballing that leads to stretched or cropped results.
Frequently asked questions
What if I do not know the ratio?
Enter both dimensions and the tool simplifies the ratio for you; for example, 1920 and 1080 yields 16:9. You can then reuse that ratio for new sizes.
Does it work with units other than pixels?
Yes. The calculation is purely proportional, so it works the same with centimeters, inches, or any unit; whatever unit you enter applies to the output too.
Is Aspect Ratio Calculator free?
Yes. Aspect Ratio Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Aspect Ratio Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.