Aspect ratio calculator
Find the aspect ratio of a resolution (16:9, 4:3, 9:16) and calculate the missing width or height while keeping the ratio.
Screen aspect ratio calculator
Everything happens on your device: nothing is uploaded to the internet.
Available in: 
Aspect ratio calculator: what it is for
Type the width and height to see the simplified ratio, the decimal ratio and the megapixels. Then enter a new width or height and the calculator finds the other dimension without distortion.
It has shortcuts for the most used ratios (16:9, 9:16, 4:3, 1:1, 4:5, 21:9) and a table with the equivalent resolutions from 480p to 4K.
How to use
- Type the width and height or choose a ratio.
- Enter the new width or height.
- Check the missing dimension and the table.
When to use it
- Resize videos and images without distortion.
- Prepare artwork for Reels, Stories and YouTube.
- Choose the resolution of monitors and screens.
Frequently asked questions
How do I find the aspect ratio of a resolution?
The calculator divides width and height by their greatest common divisor. 1920 × 1080 becomes 16:9.
Which ratio should I use on each network?
Reels, Stories, TikTok and Shorts use 9:16 (1080 × 1920). The Instagram feed accepts 4:5 (1080 × 1350) and 1:1. YouTube uses 16:9.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.