Historical Volatility (HV) measures dispersion over time. Before diving into the HV calculation, it's important to understand what it refers to and how it helps us in trading. Historical volatility is a statistical measure of how far away from its average price an asset has fluctuated in your chosen time period. While this sounds complicated at first glance, it's actually quite simple — let's find out more about historical volatility.Historical volatility is a statistical measure of the dispersion of prices in a given period of time. Like any other metrics out there, historical volatility can help you make more accurate predictions and more informed decisions. Historical volatility smoothes data on the assumption that past returns will reflect future returns.Historical volatility is a measure of the average deviation from the average price of a given financial instrument over a certain period of time. It is typically calculated by determining the standard deviation (of individual stock's or index's price movements) and multiplying it by 3.Using standard deviation is the most common, but not the only way to calculate historical volatility.