Aspect Ratio Calculator: Calculate & Resize Dimensions

Aspect ratio is the proportional relationship between the width and height of an image, video, or display. Getting it wrong means stretched faces, black bars, or cropped content. Understanding common ratios and how to scale dimensions correctly saves time and avoids embarrassing design mistakes.

What Is Aspect Ratio?

Aspect ratio is expressed as width:height. A 16:9 ratio means that for every 16 units of width, there are 9 units of height. The actual pixel dimensions can vary — a 1920×1080 video and a 1280×720 video both have a 16:9 ratio. Aspect ratio describes the shape, not the size.

To simplify a ratio, divide both numbers by their greatest common divisor (GCD). For example, 1920 and 1080 are both divisible by 120, giving the simplified ratio 16:9.

Common Aspect Ratios

Why Maintaining Aspect Ratio Matters

When you resize an image or video to different dimensions without preserving the ratio, you distort the content. People look stretched or squished, circles become ovals, and logos appear warped. This is one of the most common mistakes in social media graphics, web design, and video production.

The correct approach is to scale proportionally: if you know the new width, the correct height is new_height = (new_width / original_width) × original_height. An aspect ratio calculator does this math instantly.

Practical Resize Examples

How to Use the Aspect Ratio Calculator