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Easy Aspect Ratio Calculator

An easy to use Aspect Ratio Calculator. Useful when resizing images and videos.

Use the tool immediately for fast results (or first skip to the explanation below).

1. Enter old width & height:

 ← Old width    ← Old height

2. Choose new dimension you already know, either:

~ or ~

3. Enter the new :

4. Behold! The new :

How it works

If you want to resize something (like an image), but wish to preserve the way it looks, you need to know something called the 'aspect ratio'. This basically is the relationship between the width and the height.

But you don't want to know about the math behind it! You just want the answer!

That's where this tool helps you:

  1. First, enter the old width and height. The tool uses it to calculate the aspect ratio behind the scenes
  2. Next, choose the new dimension you already know (new width or new height)
  3. Now, enter the value of that dimension
  4. Finally, the tool will tell you the value of the other dimension, based on the aspect ratio of the old image

That's it! The tool will tell you either the new width or height (depending on what you've chosen in step 2).

'Aspect ratio', Uhhh ..., wut?

Wikipedia explains it like this:

The aspect ratio of an image describes the proportional relationship between its width and its height. It is commonly expressed as two numbers separated by a colon, as in 16:9. For an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this same length unit, the height will be measured to be y units.

In, for example, a group of images that all have an aspect ratio of 16:9, one image might be 16 inches wide and 9 inches high, another 16 centimeters wide and 9 centimeters high, and a third might be 8 yards wide and 4.5 yards high.


Aspect ratio formula

There is a simple formula for calculating aspect ratios: aspectRatio = ( oldWidth / oldHeight ). For instance if you want to know the new height of an object, you can use: newHeight = ( newWidth / aspectRatio ), and if you need the new width of an object, you can use: newWidth = ( newHeight * aspectRatio ).

So first you need to know the aspect ratio by dividing the old width by the old height, and then you can use that to calculate either the new width or new height.

What's next?

Not much really. But if you think this was useful to you, it might be for others also: