Fancybox is a pretty cool lightbox plugin for jQuery that I have been using for awhile now. It’s got a great feature set, looks good, and for the most part it just works out of the box. There is however one thing that was mind numbingly hard to figure out, and that was how to automatically set the height of an iframe lightbox. Fancybox has this functionality built in for inline content via the autoDimensions key, which is set to true by default. Unfortunately this is not the case for iframes. After some hair pulling I managed to piece together an auto height solution for Fancybox iframes, but this technique could also be used without Fancybox to find the height of any iframe.