Bollinger Bands are a technical analysis tool invented by John Bollinger in 1980. It is mainly used to analyze market volatility and trend strength, and can be used as an indicator of overbought or oversold. Bollinger Bands are composed of three lines: the middle line is usually the 20-day moving average, and the upper and lower bands are the standard deviation of the middle line. When the price of an asset is close to the upper band, it may indicate an overbought condition; when it is close to the lower band, it may indicate an oversold condition. Source: IBKR On the basis of Bollinger Bands, Bollinger Band Width and Bollinger %B are also derived. Bollinger Bands is a measure of the width of the Bollinger Bands, expressed as a numerical value that reflects market volatility. When the width of Bollinger Bands is large, it indicates strong market fluctuations; when the width of Bollinger Bands is small, it indicates weak market fluctuations. Bollinger Bands Percentage measures the position of an asset's price relative to the Bollinger Bands, reflecting the overbought or oversold status of the market. When the asset price is close to the upper track, the Bollinger Bands percentage is close to 1, indicating that it may be overbought; when the asset price is close to the lower track, the Bollinger Bands percentage is close to 0, indicating that it may be oversold. Therefore, through the values of the Middle Band, Upper Band and Lower Band, Bollinger Bands can be drawn, usually drawn together with the price line, as shown in the figure below: Next, we can calculate Bollinger Band Width and Bollinger %B. These two values are usually displayed on separate charts. Bollinger Band Width indicates the relative width of the Bollinger Bands and reflects changes in market volatility. When the bandwidth increases, it indicates that market volatility increases; when the bandwidth decreases, it indicates that market volatility decreases. The calculation formula of Bollinger Bandwidth is as follows: Bollinger Bands Percentage measures the current price relative to the Bollinger Bands position. This indicator is calculated by comparing the current price to the lower and lower bounds of the Bollinger Bands, helping to identify overbought or oversold conditions, as well as potential buying and selling points. The value of %B ranges from 0 to 1, with a value above 1 indicating overbought and a value below 0 indicating oversold. The calculation formula is as follows: Bollinger Band Width and Bollinger %B are generally displayed below the price line, such as: How to use Bollinger Bands, Bollinger Bands Bandwidth, and Bollinger Bands Percent? Bollinger Bands consist of two upper and lower boundary lines and a middle line, and are usually drawn on charts together with the price line. Common uses of Bollinger Bands, Bollinger Band Width, and Bollinger Band Percent are as follows: Determine price trends When the bandwidth of Bollinger Bands expands, it indicates increased market volatility and often signals the beginning of a trend. When the bandwidth of Bollinger Bands narrows, it indicates a decrease in market volatility, which is usually a signal that the trend is weakening or the market is entering a consolidation phase. Source: TradingView Determine overbought or oversold Consider using Bollinger Bands in conjunction with other overbought and oversold indicators (such as RSI, CCI, etc.). When the price approaches or touches the lower band of the Bollinger Bands and the RSI also shows that the market is oversold, this is generally considered an oversold market and may indicate a price reversal. If the RSI is not indicating oversold, then price approaching the lower band may just indicate that the market still has room to fall. What are the limitations of using Bollinger Bands? As a popular technical analysis tool, Bollinger Bands can effectively help you identify market volatility, trend strength, and overbought and oversold conditions, but it also has certain limitations, especially when used alone. Bollinger Bands mainly relies on historical price data to calculate the current price fluctuation range. It can show the position of price relative to the upper and lower rails of Bollinger Bands, but it cannot accurately predict the direction or magnitude of future prices. In other words, Bollinger Bands can only provide a picture of current market volatility and cannot predict how the market will continue to develop. Therefore, relying solely on Bollinger Bands to make trading decisions may lead to misjudgments, especially when prices fluctuate wildly.
Meanwhile, Bollinger Bands are calculated based on moving averages and standard deviations, which rely on past price data. Therefore, Bollinger Bands are lagging in nature and cannot respond to rapid changes in the market immediately. In rapidly volatile markets, Bollinger Bands may not be able to capture sharp changes in price in time, causing delays in trading signals. In sideways markets with no clear trend, Bollinger Bands can produce misleading signals. Since the upper and lower rails of the Bollinger Bands will frequently contact the price in the sideways market, it may cause traders to frequently enter and exit the market, thus increasing transaction costs and risks. Under such market conditions, the signals of Bollinger Bands are not always reliable, and "false breakthroughs" or "false pullbacks" may occur, causing unnecessary losses to traders. Therefore, Bollinger Bands are most effectively used in conjunction with other technical indicators, such as the Relative Strength Index (RSI), MACD, support/resistance levels, etc. By combining multiple indicators, you can more fully assess market conditions and reduce the misleading signals that can occur when Bollinger Bands are used alone. For example, Bollinger Bands may show that the price is close to the upper band, but if the RSI does not reach the overbought zone, the price may still continue to rise. Therefore, using Bollinger Bands in conjunction with other technical analysis tools can help you make more accurate trading decisions. More technical indicators What are Fibonacci retracements? Fibonacci Retracement What is the application accumulation/distribution line? A/D Line What is the Commodity Channel Index CCI? How to use the CCI indicator? What is the Stochastic Oscillator? What is the Average Trend Indicator ADX? How to use the ADX indicator? What is the Balanced Volume Indicator? How to use the OBV indicator? What is Moving Average MA? Moving Average What is Moving Average Convergence Divergence (MACD)? What is the Money Flow Index MFI?