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Technical Indicators

Mon, Jul 7th, 2025
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The descriptions, formulas, and parameters shown below apply to both Interactive Charts and Snapshot Charts, unless noted. Please note that some of the parameters may be slightly different between the two versions of charts.
Studies noted with * are available only in Snapshot Charts and those noted with ^ are available only in Interactive Charts.
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Bollinger Bands %B

Indicator Type: Standalone - Interactive Charts Only

Bollinger Band Percent (BB %B) quantifies a symbol's price relative to the upper and lower Bollinger Band. There are six basic relationship levels:

  • %B equals 1 when price is at the upper band
  • %B equals 0 when price is at the lower band
  • %B is above 1 when price is above the upper band
  • %B is below 0 when price is below the lower band
  • %B is above .50 when price is above the middle band (20-day SMA)
  • %B is below .50 when price is below the middle band (20-day SMA)

Sample Chart:

Bollinger Percent (BB%B)

%B can be used to identify overbought and oversold situations. However, it is important to know when to look for overbought readings and when to look for oversold readings. As with most momentum oscillators, it is best to look for short-term oversold situations when the medium-term trend is up and short-term overbought situations when the medium-term trend is down. In other words, look for opportunities in the direction of the bigger trend, such as a pullback within a bigger uptrend. Define the bigger trend before looking for overbought or oversold readings.

%B quantifies the relationship between price and Bollinger Bands. Readings above .80 indicate that price is near the upper band. Readings below .20 indicate that price is near the lower band. Surges towards the upper band show strength, but can sometimes be interpreted as overbought. Plunges to the lower band show weakness, but can sometimes be interpreted as oversold. A lot depends on the underlying trend and other indicators. While %B can have some value on its own, it is best when used in conjunction with other indicators or price analysis. 

Calculation:

%B = (Price - Lower Band)/(Upper Band - Lower Band)

The default setting for %B is based on the default setting for Bollinger Bands (20,2). The bands are set 2 standard deviations above and below the 20-day simple moving average, which is also the middle band. Security price is the close or the last trade.

Default Parameters:

  • Period (20) - the number of bars, or period, used to calculate the study. John Bollinger, the creator of this study, states that those periods of less than ten days do not seem to work well for Bollinger Bands®. He says that the optimal period for most applications is 20 or 21 days.
  • Width (2) - The half-width of the band in terms multiples of standard deviation. Typically 2 is used. John Bollinger suggests, if you reduce the number of days used to calculate the bands, you should also reduce the number of deviations and vise versa. For example, if you use a period of 50, you may want to use 2.5 as the standard deviation. For a period of 10, you may want to use 1.5 or 1.0. The application uses a default of 2.0
  • Overbought Value (1) - position where the overbought line is drawn.
  • Oversold Value (0) - position where the oversold line is drawn.

Adapted from StockCharts.com

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