Bollinger Bands are a type of statistical chart characterizing the prices and volatility over time of a financial instrument or commodity, using a formulaic method propounded by John Bollinger in the 1980s. The bands are plotted at standard deviation levels above and below a moving average, which is typically the simple moving average (SMA). The bands are calculated using the following formula:
Upper Band = SMA + (n * Standard Deviation)
Lower Band = SMA - (n * Standard Deviation)