Find the ratio (like 16:9) from a width and height, or compute dimensions from a ratio
An aspect ratio is the proportional relationship between the width and height of an image or screen. For example, a 1920x1080 screen is 16 wide for every 9 tall, so it is written as 16:9. It is used to scale videos, photos and displays up or down while keeping the same shape.
Yes. In the "Ratio to dimensions" mode, set the ratio to 16:9 and enter 1280 as the width, and the height is calculated as 720 automatically. You can also enter a height to get the width. When the result is not a whole number, a rounded approximation is shown.
No. All calculations run entirely in your browser with JavaScript. The numbers you enter are never transmitted to or stored on a server.