Aspect Ratio Calculator
Calculate aspect ratios, resize dimensions proportionally, and find equivalent resolutions.
What is an Aspect Ratio?
An aspect ratio describes the proportional relationship between the width and height of an image or screen. It is usually expressed as two numbers separated by a colon, such as 16:9. The first number represents the width, and the second represents the height. Aspect ratios are independent of the actual size or resolution in pixels; an image of 1920x1080 pixels has the same 16:9 aspect ratio as an image of 1280x720 pixels.
Common Aspect Ratios
- 16:9 (Widescreen): The standard format for modern HD monitors, televisions, and online video platforms like YouTube.
- 4:3 (Classic/Standard): Used by older CRT televisions and early computer monitors. Still used in some photography formats.
- 1:1 (Square): Equal width and height. Popularized by social media platforms like Instagram.
- 21:9 (Ultrawide): A cinematic format often used for movies and modern ultrawide gaming monitors.
- 9:16 (Vertical): The standard portrait orientation for smartphones, used in TikTok, YouTube Shorts, and Instagram Reels.
- 3:2 (Photography): The classic aspect ratio of 35mm film, still standard on most DSLR and mirrorless cameras.
How to Calculate Aspect Ratios
To calculate the aspect ratio of an image, divide the width by the height. If you want to resize an image while maintaining its original proportions (so it doesn't look stretched or squished), you must scale both dimensions by the same factor. For example, if you have an image that is 1000 pixels wide and 500 pixels high, the aspect ratio is 2:1. If you want to change the width to 500 pixels, you must also halve the height to 250 pixels to maintain the 2:1 ratio.
How Does This Tool Work?
Our aspect ratio calculator runs entirely in your web browser. When you input dimensions, JavaScript calculates the ratio and proportional sizes instantly. Because all processing happens client-side, it is fast, secure, and works entirely offline once loaded.