Aspect Ratio Calculator
Calculate missing dimensions, scale proportionally, or find the ratio from any two dimensions.
About Aspect Ratios
An aspect ratio is the proportional relationship between an image or screen's width and height, expressed as two numbers separated by a colon (e.g. 16:9). 16:9 is the standard widescreen format used by most monitors, TVs and YouTube videos. 4:3 was the classic TV and computer monitor format. 1:1 is square, used widely on Instagram. 9:16 is vertical/portrait, used for TikTok, Instagram Stories and mobile video.
The ratio is calculated by dividing both dimensions by their Greatest Common Divisor (GCD). For example, 1920×1080 simplifies to 16:9 because both are divisible by 120. Use the Scale mode to calculate a missing dimension when you know the ratio and one measurement — essential for responsive design and image resizing without distortion.