How to Calculate Competition Level

I am confuse that how to calculate the competition level. Normally we see just low competition, medium and high. Some one has any idea about it how we can calculate it in figure like 3, 3.5, 4.or 5.

It is easy to evaluate the keyword competition level.

You have any idea about it?

Please search this forum to see if your question has already been asked before you post another thread. We have a sticky thread on this very subject, right at the top of the forum, titled ā€œImportant: Competitive Keyword Analysis, how do YOU do it?ā€