Aspect Ratio Calculator

Calculate aspect ratios and find missing dimensions. Includes common presets like 16:9, 4:3, and 21:9.

Original width

Original height

New width

New height

Original ratio —

New ratio —

Match —

Common preset

Features

Width/height → ratio

Ratio + one side → other side

Common presets (16:9, 4:3, etc.)

Visual preview

How to Use

1. Type the original width and height.

2. The aspect ratio is shown automatically.

3. Or type a target width to find the matching height (or vice versa).

About this tool

An aspect ratio describes shape, not size: a 1920 × 1080 video and a 1280 × 720 video are both 16:9. This calculator reduces any width and height to its simplest ratio by dividing both by their greatest common divisor, then helps you scale to a new size without stretching. Enter the original dimensions, type one of the new ones, and the other is filled in so the proportions stay identical; the "Match" line confirms whether your new pair keeps the same shape. It is handy for resizing images for social posts, planning video exports, fitting embeds into a layout, or checking whether a screenshot will crop when it is shown at 4:3 or 21:9.

Frequently Asked Questions

How is the ratio simplified?

Width and height are divided by their greatest common divisor. For example, 1920 and 1080 share a divisor of 120, which gives 16:9. Sizes that do not simplify neatly, such as 1366 × 768, produce less familiar ratios like 683:384.

How do I find the height for a new width without distortion?

Enter the original width and height, then type the new width. The new height is calculated as new width × original height ÷ original width, so the image keeps exactly the same proportions.

What does the Match indicator mean?

It compares the original ratio with the ratio of your new width and height. YES means they are the same shape within a very small tolerance; NO means the new size would stretch or squash the content, or require cropping.

Which aspect ratios are the most common?

16:9 is standard for HD video and most monitors, 4:3 for older displays and many tablets, 21:9 for ultrawide screens, 1:1 for square social posts, 9:16 for vertical phone video, and 3:2 for many camera photos.

Why does my resized image still look blurry?

A correct ratio prevents stretching but cannot add detail. Enlarging a small image beyond its original pixel size will look soft; for sharp results, scale down from a larger source instead of scaling up.