How it is calculated

The price minus the lower band, divided by the upper band minus the lower band. The bands are the catalogue's Bollinger Bands with the same length, mult and source (SMA plus and minus mult population standard deviations). When every price in the window is the same the bands have no width and %B has no value. After Bollinger 2001.

Reference: Bollinger 2001, bands as TA-Lib BBANDS

How to read it

Above 1 the price is above the upper band, below 0 under the lower one. Readings that stay near 1 in an uptrend show strength rather than a top. Comparing %B highs with price highs can show a divergence: price makes a new high, %B does not.

In a strategy

A rule that does not depend on the price level: buy when ctx.ind("bbp", length=20) rises back above 0 after closing below it, or take profits when it reaches 1.

Inputs

Input	Type	Default	Range or choices
Length`length`	Whole number	`20`	min 2, max 5000
Multiplier`mult`	Number	`2`	min 0.1, max 10
Source`source`	Price	`"close"`	close, open, high, low, hl2, hlc3, ohlc4, hlcc4

What it draws

Line	Drawn as
%B	Line

Guide lines at 0, 1.

Used in

No strategy template reads it yet.