📐Aspect Ratio Calculator

Calculate aspect ratios and resize dimensions proportionally.

Width (px)

Height (px)

Simplified Ratio

16:9

Decimal Ratio

1.7778

About Aspect Ratio Calculator

The Aspect Ratio Calculator lets you calculate unknown dimensions when resizing images or videos proportionally, find the ratio of any width/height pair, and convert between common aspect ratios like 16:9, 4:3, and 1:1. It's an essential tool for designers, video editors, and developers working with responsive media.

How to Use Aspect Ratio Calculator

1
Enter your original dimensions
Type the current width and height of your image, video, or container.
2
Enter the known new dimension
Type either the new width or new height you want to scale to.
3
Get the calculated result
The missing dimension is calculated instantly, showing you the exact size needed to maintain the original aspect ratio.

Common Use Cases

Resizing images for web while maintaining the original proportions
Calculating video export dimensions for different platform requirements
Designing responsive containers that maintain consistent aspect ratios
Finding the correct thumbnail dimensions for a specific aspect ratio format

Frequently Asked Questions

How do I find the missing dimension when resizing proportionally?

Enter the original width and height plus the new width (or height) you want, and the calculator instantly computes the missing dimension to preserve the exact aspect ratio.

What common aspect ratios does the tool include?

The tool includes presets for 16:9 (widescreen HD), 4:3 (traditional TV/photo), 1:1 (square), 9:16 (portrait video), 21:9 (ultrawide), and more, with the ability to enter any custom ratio.

Can I use this for video resolution calculations?

Yes — enter your source video resolution and target display size to calculate the correct output dimensions while maintaining the original aspect ratio without distortion.