--- title: "Bollinger %B: Formula, Meaning & Signals" description: "Percent B shows where the price sits relative to the Bollinger Bands, scaled so that the lower band is 0 and the upper band is 1. It turns the band position..." canonical: https://www.getswoopr.com/indicators/volatility/bollinger-percent-b/ source: "Swoopr Investment: https://www.getswoopr.com" --- ## Direct Answer > Bollinger %B is a volatility measure used to measure dispersion, range, implied uncertainty, or expansion/contraction in price movement. The production page must define the exact calculation convention before interpreting higher or lower readings, because platform and provider implementations can differ. # Bollinger %B: Formula, Meaning, Signals, Examples and How to Use It ## How Is Bollinger %B Calculated? Percent B shows where the price sits relative to the Bollinger Bands, scaled so that the lower band is 0 and the upper band is 1. It turns the band position into a single number. **Formula:** `%B = (Price - Lower band) / (Upper band - Lower band)` **Inputs:** - Latest price (usually the close) - Lower Bollinger Band - Upper Bollinger Band **Worked example.** A price of 103 between bands at 94 and 106 gives %B of 0.75. The inputs are illustrative numbers, not market data. **Reading it.** A value of 0.5 is the middle of the bands; above 1 means price is above the upper band, and below 0 means it is below the lower band. It does not say whether such readings mean continuation or reversal. **Limits.** The values depend on the band settings and are not bounded to 0 through 1, since price can close outside the bands. In strong trends it can stay near one extreme for a long time. ## Indicator overview | Attribute | Value | | --- | --- | | Category | Volatility | | Asset classes | Stocks, ETFs, Indexes, Options, Futures, Forex, Crypto, Commodities | | Output type | Line/scalar | | Parameters | Varies by implementation; document exact settings on use | ## What is Bollinger %B? Bollinger %B is a volatility measure used to measure dispersion, range, implied uncertainty, or expansion/contraction in price movement. The production page must define the exact calculation convention before interpreting higher or lower readings, because platform and provider implementations can differ. For Swoopr, the canonical profile separates definition, calculation, interpretation and decision use. That keeps readers from collapsing a descriptive metric into a trading strategy. An indicator can describe trend, momentum, volatility, participation, positioning or risk without providing a complete entry, exit, sizing or portfolio decision. ## What does it measure? Bollinger %B measures specific market properties in the Volatility domain. The practical value is repeatability: the same inputs and formula can be applied across a defined dataset, allowing users to compare readings through time or across instruments when the calculation convention is held constant. ## How to read Bollinger %B Interpretation depends on the market property being measured. A descriptive reading is not automatically predictive. The same numerical state can lead to different outcomes in a strong trend, quiet range, event-driven gap or illiquid market. Always combine with context from price structure, volume, and broader market regime before drawing conclusions. ## Strengths - Rescaling price to the band span turns position into one number, so above 1 or below 0 marks a close outside the bands directly. - Because the bands adapt to standard deviation, the same percent B corresponds to a comparable distance in deviations across instruments. - Reproducible when the formula and data convention are fixed. ## Weaknesses and limitations - The denominator is the band width, so when the bands are tight a small price move produces a large change in percent B. - Percent B and bandwidth are separate outputs of the same bands, so a reading of 0.5 says nothing about whether bands are wide or narrow. - Correlated indicators can create false confidence by repeating the same underlying information. ## Editorial and risk note This page is educational content, not individualized investment advice. It should not imply guaranteed prediction, accuracy or outperformance. Where multiple valid definitions exist, Swoopr states the alternatives and the reason for selecting its primary convention. ## Frequently Asked Questions Is Bollinger %B a buy or sell signal? No. A value of 0.5 is the middle of the bands; above 1 means price is above the upper band, and below 0 means it is below the lower band. The values depend on the band settings and are not bounded to 0 through 1, since price can close outside the bands. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions. What is the best setting for Bollinger %B? Bollinger %B is computed from latest price (usually the close); lower Bollinger Band; upper Bollinger Band, so the choices that matter are the data convention and the window it is read over. Test those across instruments, regimes and out-of-sample periods instead of fitting one historical winner. Can Bollinger %B be used by itself? The values depend on the band settings and are not bounded to 0 through 1, since price can close outside the bands. In strong trends it can stay near one extreme for a long time. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone. Does Bollinger %B work on every timeframe? The calculation (%B = (Price - Lower band) / (Upper band - Lower band)) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it. Why does Bollinger %B give false signals? The denominator is the band width, so when the bands are tight a small price move produces a large change in percent B. Percent B and bandwidth are separate outputs of the same bands, so a reading of 0.5 says nothing about whether bands are wide or narrow. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated. How should Bollinger %B be backtested? Rebuild Bollinger %B from latest price (usually the close) using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline. ## References - [Bollinger Capital Management: A Complete Explanation of Bollinger Bands](https://www.bollingerbands.com/bollinger-bands) S Swoopr Editorial Team The Swoopr Editorial Team produces independent investment education, research, and tools for understanding markets, evaluating opportunities, and managing risk. All content is educational only and does not constitute personalized investment advice. See our [editorial policy](https://www.getswoopr.com/legal/editorial-policy/) and [corrections policy](https://www.getswoopr.com/legal/corrections-policy/).