How long does it take to get a post-doctoral degree?

Answer 1

I am not aware of any such thing as a postdoctoral degree. You may be referring to postdoctoral research which may be required for obtaining a tenure-track faculty position, especially at research oriented institutions. Some have suggested that postdoctoral appointments - that were traditionally optional - have become mandatory as demand for tenure-track positions in academia has drastically increased over previous decades (Wikipedia). The length of time in this case depends on the type, content, scope, and depth of the research.

Answer 2

It is not exactly a degree. It is just referred to a post-doctoral research. In some counties the research my lead to some type of qualification or certification, however, in other countries it does not. There are some institutions within the US that may require post-doctoral study for tenure track. The work can be accomplished either independently or by supervision of a designated individual.