I have 2 different sources for historical volatility data. One is ivolatility.com and the other is Robert's Historical Stock volatilities. I want to know the volatility on GOOG right now. I get different numbers from the different sources. I will show below Roberts "1 month" volatility on goog is 16% ivolatility.com volatility on goog is 20.6% 1 month ago. right now ivolatility says the volatility on goog is 39% BTW, none of this is implied volatility. Obviously either they are feeding their data differently or I am reading their data wrong. Can someone help that knows more about this. Is Robert's "1 month" referring to this month or 1 month ago? what about 5 year? Does anyone have their own accurate source? What is Goog volatility right now? what about their 30 day Historical volatility 30 days ago?