Find the aspect ratio of any width and height, and scale dimensions proportionally.
Instant and private in your browser.
How do you calculate an aspect ratio?
The ratio is width:height divided by their greatest common divisor; a new height = new width × (height ÷ width). For example, 1920 × 1080 reduces to 16:9 (1.778:1), and scaled to 1280 wide the height is 720. Common ratios include 16:9 (widescreen), 4:3 (classic), 1:1 (square) and 21:9 (ultrawide).
Understanding your result
Common ratios include 16:9 (widescreen), 4:3 (classic), 1:1 (square) and 21:9 (ultrawide).
Formula and method
The ratio is width:height divided by their greatest common divisor. A new height = new width × (height ÷ width).
Worked example
1920 × 1080 reduces to 16:9 (1.778:1). Scaled to 1280 wide, the height is 720.
How to use this tool
- Enter the width and height.
- Optionally enter a new width to get the matching height.
- Press Calculate.
About the Aspect Ratio Calculator
The Aspect Ratio Calculator reduces any width and height to its simplest ratio and helps you resize images or video while keeping the proportions correct.
Explore all Productivity tools
Frequently asked questions
How do I keep an image in proportion?
Enter the original width and height, then a new width — the calculator gives the height that preserves the ratio.