The Bollinger Bands® study consists of two lines plotted, by default, two standard deviations above and below a moving average of specified type and length. Standard deviation changes as price volatility increases or decreases.

The upper band represents the overbought level while the lower one represents the oversold level: trading might be profitable at either low price or high price relative to the market and prior price action. However, price approaching or bouncing off either band is not necessarily a sign of reversal or breakthrough.

Input Parameters

Parameter Description
price The price used to calculate the moving average and deviations.
displace The number of bars to shift the study forward or backward. Positive numbers signify a backward displacement.
length The number of bars used to calculate the moving average and standard deviations.
num dev dn The number of deviations to plot the lower band.
num dev up The number of deviations to plot the upper band.

average type

The type of moving average to be used in calculations: simple, exponential, weighted, Wilder's, or Hull.


Plot Description
MidLine The moving average.
LowerBand The lower band.
UpperBand The upper band.


*For illustrative purposes only. Not a recommendation of a specific security or investment strategy.

Bollinger Bands® is a registered trademark of John Bollinger.