Here’s a free site that I use quite a bit.  It lets you easily calculate the missing value for an aspect ratio.  I use this a lot when I try to figure out the size of photos or widgets that I want to embed on slides or web pages.

Let’s say you have a picture that’s 800×662 pixels wide, but you can only put a 400 pixel wide image on your blog.  So you need to scale it down, but keep the same aspect ratio.

You can see the aspect ratio calculator in action in the tutorial below.

Click here to view the aspect ratio tutorial.

So now you’re never at a loss to quickly calculate the aspect ratios for any of your multimedia projects.