Aspect Ratio Calculator
Find the ratio of any size and resize images or video without stretching.
The Aspect Ratio Calculator finds the simplified ratio of any width and height, such as 1920x1080 becoming 16:9. Enter a new width or height and it fills in the missing side so your images or video keep the same proportions. Everything runs in your browser, with no uploads. Made by FreeToolHub.
Aspect ratio
Resize keeping the ratio
How it works
Set an aspect ratio by typing a width and height or picking a common ratio. The calculator simplifies it with the greatest common divisor and shows the decimal value. In the resize section, enter a new width or height and the other side updates automatically so your image or video keeps its proportions.
Frequently Asked Questions
What is an aspect ratio?
An aspect ratio is the proportional relationship between width and height, written as two numbers like 16:9. It describes the shape of an image or screen, not its actual size, so 1280x720 and 1920x1080 share the same 16:9 ratio.
How do I calculate an aspect ratio?
Divide the width and height by their greatest common divisor to reduce them to the smallest whole numbers. For 1920x1080 the greatest common divisor is 120, which simplifies the ratio to 16:9. This calculator does that reduction for you automatically.
How do I resize an image without stretching it?
Keep the same aspect ratio. Enter your original width and height to set the ratio, then type the new width and let the calculator work out the matching height, or the reverse. Using those exact numbers keeps the image from stretching or squashing.
What are the most common aspect ratios?
16:9 is standard for video, TVs, and most monitors. 4:3 is used by older screens and many photos. 1:1 is square and popular on social media. 21:9 is ultrawide, and 9:16 is vertical for phone video and stories.
What is the difference between aspect ratio and resolution?
Resolution is the exact pixel count, such as 1920x1080. Aspect ratio is the shape those pixels form, such as 16:9. Many different resolutions can share one aspect ratio, and this tool shows both for any size you enter.
Does this calculator upload my images?
No. The Aspect Ratio Calculator only works with the width and height numbers you type. Nothing is uploaded, stored, or tracked, and every calculation happens instantly in your browser.