Aspect Ratio Calculator
Calculate aspect ratios for any image, video, or screen dimension. Find missing dimensions from a known ratio, check if two sizes are proportional, and convert between common ratios like 16:9, 4:3, and 1:1.
Embed this Tool on Your Website
Copy this code snippet to add the Aspect Ratio Calculator to your blog or website for free. It adjusts dynamically to mobile and desktop screens.
How to Use Aspect Ratio Calculator
Aspect Ratio Calculator Formula / How It Works
The calculator finds the Greatest Common Divisor (GCD) of the two input values using the Euclidean algorithm and divides both by it to produce the simplest whole-number ratio. Missing dimensions are found by multiplying the known dimension by the inverse ratio.
For example, entering 1920 × 1080 produces a ratio of 16:9. Entering a target of 1280 × 720 confirms the proportions match at 16:9 with a scale factor of 0.67×.
Frequently Asked Questions
Enter the image width and height in pixels into the Ratio Finder tab. The calculator divides both values by their Greatest Common Divisor (GCD) to display the simplified ratio, such as 16:9 or 4:3.
Go to the Missing Dimension tab. Enter your known dimension (width or height), select which one it is, and enter the target ratio. The calculator multiplies or divides by the ratio to find the missing value.
When you fill in both Original and Target dimensions in the Ratio Finder tab, the tool checks whether they share the same aspect ratio. A green indicator means the proportions match; amber means they differ.
The scale factor shows how much larger or smaller the target dimensions are compared to the original. A scale factor of 0.5× means the target is half the size; 2.0× means it is twice as large.
YouTube recommends 16:9 for all uploads. The standard HD resolution is 1920×1080 pixels. The minimum recommended width is 1280 pixels at 16:9, which gives a height of 720 pixels.
