This new TV show called Scorpion claimed that Einstein's IQ was "only 165" while the main character has an IQ of 178. I realize the show is full of crap, but I keep hearing that number for Einstein. Is this just someone's best guess, or do we actually have a record of him taking a reliable IQ test? If so, can you link the source?
As far as we known today, Albert Einstein has never done any IQ test. Thus his IQ is unknown!
In the 1920'ies scientists had tried to estimate the IQ of deceased personalities such as Mozart (1756-1791) and Goethe (1749-1832) by means of biographic data; thus they wanted to estimate Albert Einstein’s IQ, too. The value estimated for Einstein was between 160 and 180. But this rough estimation can not count as Einstein’s IQ!
Remember the standard IQ-test will show a persons ability to think logically and solve problems and is not a real indicator to how smart someone is. This has far too many variables to be indicated in one single quotient.
Source: http://www.einstein-website.de/z_information/variousthings.html#iq
The source may look a bit shady, but it's been reliable in my experience.