Bollinger Bands: Definition, How it Works, Importance, Formula, and Calculations

Bollinger bands is a technical analysis tool used for identifying the prices and volatility of securities and commodities. Bollinger bands are used by traders for analyzing overbought and oversold conditions of securities and commodities. Bollinger Bands are composed of Three lines: Simple Moving Average (SMA) band (middle), Positive standard deviation (upper) band and Negative standard deviation (lower) band.

Bollinger Bands were developed by John Bollinger with the purpose of giving investors a tool to identify the volatility of assets with high probability. The upper and lower bands are used to determine the volatility(degree of price variation) of the market. 

The Bollinger Bands is a chart overlay indicator, which means that the bands are projected over the price of the security. The bands move apart when the market becomes volatile and the bands come closer when the market is quiet. 

What are Bollinger Bands?

Bollinger bands is a technical analysis tool used by traders to identify the volatility of securities in the market. Bollinger bands was developed in the 1980s and since then it is one of the most popular technical analysis tools used by traders.

The Bollinger bands are plotted with the help of three lines. The middle line is a moving average line that can be varied as per convenience (usually a 20-day moving average) and the two outer bands are two standard deviations away from the moving average line. These outer bands are calculated using a formula that uses recent price changes of the securities being analyzed. 

The space between the outer bands helps in identifying the volatility in the market.  The space between Bollinger bands widens when the volatility of the market is high. The outer lines of the Bollinger bands shrink when the market volatility is low. Traders can use this to assess market conditions and adjust their trading strategies accordingly.

Bollinger Bands works on two parameters, the first is Period and the second is Standard Deviations. The values for the period used for the moving average can be varied by the trader as a convenience. The default value for standard deviations is 2, meaning that the outer bands are set at two standard deviations above and below the moving average line in the middle. 

How do Bollinger Bands work?

Bollinger Bands work by projecting a visual representation of the volatility of an asset and identifying potential buy and sell signals for traders. Below is a graphical representation of the same.

The outer and inner bands are created by calculating the moving average of an asset over a specific period and adding and subtracting a specific multiple of the standard deviation from the moving average. 

The overbought and oversold conditions are identified using Bollinger Bands, to generate buy and sell signals, when the prices of securities touch the upper and lower bands. This ultimately Indicates that the security is due for a price correction or reversal. 

For example, It is a good time to buy the stock of a company XYZ, when the price of stocks is touching the lower band, as it indicates that it may be oversold and its price may increase in future. It is a good time to sell the stock when the price of a security is near the upper band, it indicates that it may be overbought and due for a price correction. Bollinger bands act as a highly useful asset for traders for generating buy and sell signals and it also helps in risk analysis by giving data about the volatility of the assets. 

What is the importance of Bollinger Bands?

The importance of Bollinger Bands lies in its ability to provide information regarding the volatility of an asset, identifying entry and exit points and trend reversals.  

The Bollinger Bands can also be used to produce sell-and-buy signals. It suggests that the asset is overbought and it is due for a price correction whenever the value of the asset is hovering above the upper band. The Bollinger Bands can also help identify oversold conditions of the assets, which is a high-potential buying position. 

Bollinger Bands is a widely versatile tool with a lot of applications for trading securities in the market. The Bollinger bands provide traders with valuable insights into market conditions and potential trading opportunities.

What is the Formula for Bollinger Bands?

Bollinger bands involve three major components: Simple Moving Average (SMA), Upper band and Lower band.

The value of all three components is derived by using the following formulas:

Middle Band = N-period simple moving average (SMA)

Upper Band = Middle Band + K times the standard deviation of N-period prices

Lower Band = Middle Band – K times the standard deviation of N-period prices

Where:

N is the number of periods used for the moving average

K is the number of standard deviations to use for the upper and lower bands

How to Calculate Bollinger Bands?

Bollinger Bands can be calculated by first selecting the number of periods for the moving average, typically 20 or 21 periods are used. One then calculates the middle band by taking the simple moving average of the prices over the selected number of periods and dividing that by the number of periods.

One next calculates the standard deviation of the prices over the same number of periods. The standard deviation is a measure of volatility and is calculated as the square root of the variance of the prices.

The upper band is calculated by taking the moving average and adding the standard deviation of the time period to it. The lower band can also be calculated similarly by taking the value of the moving average but by subtracting the standard deviation from it. 

What are the three lines of Bollinger Bands?

Bollinger Bands are composed of three lines – the upper, middle, and lower bands. The trader selects the specifications for the middle band’s moving average.

The upper and lower bands are placed on either side of it, about the moving average band.

1. Upper Bollinger Band

Upper Bollinger Band is calculated by adding a specified number of standard deviations (usually two) to the middle band. The upper band represents the upper boundary of the price range and is typically interpreted as a potential resistance level.

2. Simple Moving Average ( Middle Bollinger Band)

This is a simple moving average (SMA) of the prices over a specified number of periods, typically 20 or 21 periods. The middle (Moving Average) band represents the average price of the security over the time periods selected by the traders as per their convenience.

3. Lower Bollinger Band

The lower band as the name suggests is the bottommost band and it is calculated by subtracting a specified number of standard deviations (usually 2) from the middle (Moving Average) band. The lower band is used by traders to find oversold positions and it represents the lower boundary of the price range.

These bands are used by traders to identify buying and selling positions for securities in the market. The three bands have a variety of applications like finding entry and exit points and these can also be used to identify overbought and oversold conditions.

Bollinger Bands can be understood better by taking a look at the example given below. 

The above example shows a case of how Bollinger bands can be used to identify the volatility of the stock. The above example shows the volatility fluctuation in the cryptocurrency. The volatility is said to be minimal when the bands are close to each other. They can be seen to be squeezed together when the volatility is low and it is vice versa when the volatility is said to be high. 

High volatility is shown when the bands move apart from each other. The upper and lower bands expand together and move away from the moving average or it can also happen with just one of the bands moving away from the moving average. It shows an increase in volatility either way. 

Which is the Best Line of the Bollinger Band?

There is no particular “best” line among the three Bollinger Bands, as each of the three lines are used for specific purposes.

The middle band is a simple moving average with a time period of 20 days and is often used to identify the current trends of the market. Traders can consider buying or selling assets like stocks, currencies, commodities, and cryptocurrencies when the price crosses above or below the middle band.

The upper and lower bands are calculated by adding and subtracting a certain number of standard deviations from the middle band. The upper band is interpreted as a potential resistance level, while the lower band is interpreted as a potential support level. Traders consider selling when the price reaches the upper band and buying when the price reaches the lower band.

How to use Bollinger Band in Technical Analysis?

Bollinger Bands can be used in technical analysis to identify potential trends, overbought and oversold conditions, and potential entry and exit points for trades. Here are three common ways to use Bollinger Bands in technical analysis:

Identify trend reversals: Bollinger Bands indicate a trend reversal when the price of a security breaks above or below the Bollinger Bands. The security is overbought, when the price breaks above the upper band, while a break below the lower band could indicate that the security is oversold.

Confirm trends: Traders can use Bollinger Bands to confirm a trend. Bollinger Bands indicate an uptrend if the price is consistently trading above the middle band. It also indicates a downtrend when the price is consistently trading below the middle band.

Identify potential support and resistance levels: The upper and lower bands of the Bollinger Bands can be used as potential resistance and support levels, respectively. Traders consider selling when the price reaches the upper band and buying when the price reaches the lower band.

The Bollinger Bands are widely used in the process of technical analysis because of the easy-to-use process and higher rate of success in determining the entry and exit points in the trade.

How to read the Bollinger Band Chart?

Reading a Bollinger Band chart involves understanding the three lines that make up the Bollinger Bands and how they relate to the price action of the security being analyzed. Here are six steps to read a Bollinger Band chart:

• Identify the middle band: The middle band is the simple moving average (SMA) line that represents the average price of the security over a specified number of periods, typically 20 or 21 periods. The middle band is the central line on the chart.

• Identify the upper and lower bands: The upper and lower bands are calculated by adding and subtracting a certain number of standard deviations (usually two) from the middle band. The upper band is plotted above the middle band, while the lower band is plotted below the middle band.

• Observe the width of the Bollinger Bands: Bollinger Bands indicate low volatility, when the bands are narrow, while wide bands indicate high volatility.

• Observe the price action: The price action of the security is plotted on the chart along with the Bollinger Bands. Traders look for instances where the price touches or crosses above or below the upper or lower bands, as this indicates potential support or resistance levels.

• Consider the trend: Traders also consider the trend of security, as indicated by the position of the price in relation to the middle band. Bollinger Bands indicate an uptrend if the price is consistently trading above the middle band. It may also indicate a downtrend when the price is consistently trading below the middle band.

• Look for potential signals: Traders use Bollinger Bands to identify buy and sell signals. A trader considers buying when the price reaches the lower band and selling when the price reaches the upper band.

Bollinger Bands can simply be applied by buying the stocks when stock prices cross below the lower band, which often helps traders take advantage of oversold conditions. This simple strategy helps traders to make a profit when the stock price moves back up toward the center moving-average line.

How to use Bollinger Bands for Day Trading?

Here are five ways that day traders use Bollinger Bands for day trading:

• Use Bollinger Bands to measure volatility: Day traders use the width of the Bollinger Bands to measure the volatility of a security. Bollinger Bands indicate low volatility when the bands are narrow and a potential breakout or trend reversal, while wide bands indicate high volatility and potential momentum.

• Use Bollinger Bands to confirm other technical indicators: Day traders use Bollinger Bands to confirm other technical indicators, such as trend lines or moving averages. It may confirm a potential buy signal when the price breaks above a trend line or moving average and reaches the upper band of the Bollinger Bands.

• Use Bollinger Bands to identify potential entry points: Day traders use Bollinger Bands to identify potential entry points when the price pulls back to the middle band. It may provide a potential buy signal If the price is in an uptrend and pulls back to the middle band. Bollinger Bands may provide a potential sell signal when the price is in a downtrend and pulls back to the middle band.

• Use Bollinger Bands to identify price targets: Day traders use the Bollinger Bands to identify potential price targets for trade. For example, the trader set a price target at the middle band, when the price is trading near the upper band. The trader also set a price target at the upper band if the price is trading near the lower band. 

• Use Bollinger Bands with multiple timeframes: Day traders use Bollinger Bands with multiple timeframes to gain a better understanding of the trend and potential signals. For example, a trader use a 5-minute chart for short-term trades and a 1-hour chart for longer-term trends.

Bollinger bands can help day traders to assess how strongly security is rising (uptrend), dropping (downtrend), and when the asset is gaining or losing strength. This can ultimately help day traders to make more efficient decisions.

What are the Best Bollinger Bands Trading Strategies?

There are five Bollinger Bands trading strategies that traders use, depending on their trading style and risk tolerance:

1. Bollinger Band Squeeze

This is a situation where the Bollinger Bands narrow down and the price of the asset trades in a tight range.

This is an indication of low volatility and a potential signal that a breakout or trend reversal may occur. Traders use this as an opportunity to enter a trade in anticipation of the upcoming move in price.

2. Reversals

Reversals occur when the price of an asset changes direction and moves in the opposite direction of the previous trend.

Traders may use Bollinger Bands to identify potential reversal signals, such as when the price touches the upper or lower band and then starts to move in the opposite direction. Reversals can provide opportunities for traders to enter trades at the start of a new trend.

3. Double Bottoms

A double bottom is a chart pattern that occurs when the price of an asset reaches a low point twice before bouncing back up.

Traders may use Bollinger Bands to identify potential double bottom patterns, such as when the price touches the lower band twice and bounces back up. This may indicate a potential trend reversal and provide an opportunity for traders to enter a long trade.

4. Riding the Bands

Riding the bands is a trading strategy where traders enter a long or short position when the price touches the upper or lower Bollinger Band, respectively, and then exit the position when the price returns to the middle band. This strategy assumes that the price will continue to move in the direction of the trend and provides traders with a clear entry and exit signal.

5. Middle Bands

The middle band of the Bollinger Bands is a moving average line that represents the mean or average price of the asset over the selected period. Traders use the middle band to identify the trend of the asset, as well as potential support and resistance levels. It may indicate an uptrend, when the price is above the middle band, it may indicate an uptrend, while when the price is below the middle band, it may indicate a downtrend. 

The middle band acts as a support or resistance level that traders can use to enter or exit positions.

The above-mentioned methods are the most widely used strategies. The strategies can however be customized as per the trader’s convenience, or they can even develop a new strategy based on their interests and risk tolerance.

The example given above shows how the prices change in the opposite direction. This is known as Reversal and can be effectively used by traders to identify the trajectory. The beginning part in the chart of the given example shows a squeeze in price, which further shows a potential trend reversal apart from the low volatility it shows.

The middle portion of the above example also shows an expansion in the volatility. The fourth strategy, which is riding the bands, can also be understood from the given example if we focus on the middle band or the moving average.  

What is the advantage of using Bollinger Bands?

Bollinger bands are a highly advantageous technical analysis tool used by traders. Following are the five advantages of using Bollinger Bands:

Identifying potential entry and exit points: Bollinger Bands can help traders identify potential entry and exit points for their trades. It may signal a potential reversal or continuation of the trend when the price touches the upper or lower band, which traders can use to enter or exit their trades.

Visual representation of price volatility: Bollinger Bands provide a visual representation of the price volatility of an asset over a given period. This can help traders identify periods of high or low volatility and adjust their trading strategies accordingly.

Flexibility: Bollinger Bands can be customized to suit the needs of different traders. Traders can adjust the period and standard deviation of the bands to match their trading style and the volatility of the asset they are trading.

Easy to use: Bollinger Bands are easy to use and can be applied to any asset, making them accessible to traders of all levels of experience.

Confirmation of other technical indicators: Bollinger Bands can be used in conjunction with other technical indicators, such as RSI or MACD, to confirm signals and improve the accuracy of trading decisions.

Bollinger Bands also have both advantages and disadvantages, just like any other technical indicator or tool. A trader should also use other indicators or tools to confirm the signals generated by Bollinger Bands 

What is the disadvantage of using Bollinger Bands?

Bollinger Bands can be a useful technical analysis tool for traders, but like any other tool, they have their disadvantages. Here are four disadvantages of using Bollinger Bands:

False signals: Bollinger Bands are based on moving averages, which means that they are lagging indicators. This can result in false signals, where the price seems to break out of the bands, but then returns to the range. Traders need to be aware of this potential drawback and use other tools to confirm any signals generated by Bollinger Bands.

Sensitivity to market conditions: Bollinger Bands are most effective in markets that are trending or have a clear direction. They can produce signals that are difficult to interpret or are false in sideways or choppy markets. 

Over-reliance on Bollinger Bands: Traders who rely solely on Bollinger Bands to make trading decisions overlook other important factors, such as market news, fundamentals, and sentiment. It is important to use Bollinger Bands as part of a comprehensive trading strategy.

Not suitable for all markets: Bollinger Bands were developed for use in the stock market, and may not be suitable for all markets or asset classes. Traders need to test the effectiveness of Bollinger Bands in different markets and adjust their strategies accordingly.

The accuracy and effectiveness of Bollinger bands is also dependent on the skills of the trader who is using them. A trader should have proper knowledge of Bollinger bands and other tools used with it to get the maximum benefits out of it.

What is an example of Bollinger Bands?

Let’s say that a trader wants to use Bollinger Bands to analyze the price of a stock. They would first plot three lines on a price chart:

A simple moving average (SMA) line is calculated by averaging the closing prices of the stock over a certain period. A 20-day SMA would add up the closing prices of the stock over the last 20 days and divide by 20.

The upper Bollinger Band line is calculated by adding two standard deviations to the SMA(Middle) line. Standard deviation is a measure of how much the price has varied from the average price over the same period.

The lower Bollinger Band line is calculated by subtracting two standard deviations from the SMA(Middle) line.

The resulting chart would show the stock’s price movements, the SMA line, and the upper and lower Bollinger Bands. The Bollinger Bands would be plotted above and below the SMA line, forming a channel around the price.

Traders can use the Bollinger Bands to analyze the stock’s price movements and identify potential trading opportunities. It can be an indication that the stock is overbought and due for a pullback when the stock’s price breaks through the upper Bollinger Band. It can also be an indication that the stock is oversold and due for a rebound when the price falls below the lower Bollinger Band.

What are the other Technical Indicators besides Relative Strength Index indicator?

Technical Indicators are tools that are used by traders in technical analysis to predict the market trajectory. Technical indicators make use of past data and changes in prices, volatility and human behavior to signal potential trends and reversals. 

Common technical indicators include Bollinger bands, Moving Averages Convergence Divergence (MACD), Stochastic Oscillator etc apart from Relative Strength Index (RSI). 

Relative Strength Index is one of the most common types of technical indicator which makes use of the past prices of a security. Relative strength index or RSI is plotted on a line graph and can be used along with other technical indicators to accurately predict the security’s trajectory. 

Which Indicators Complement Bollinger Bands the Best?

Bollinger bands can be used along with technical indicators like Relative Strength Index and Moving Averages. There cannot be a one-fit-all answer to this question, since there are thousands of indicators and different indicators work for different people. But RSI is heavily relied on by a majority of traders and it has been helpful as well. Using multiple indicators together would help traders to confirm a signal or an indication.  

What is considered a good Bollinger Band?

A “good” Bollinger Band would be one that accurately reflects the price movements of the asset being traded and provides useful information for making trading decisions. This means that the Bollinger Bands should be appropriately calibrated for the market being analyzed, with the SMA line and standard deviation values that reflect the volatility of the asset. 

Bollinger Bands are more effective in markets that are trending or have a clear direction, rather than those that are choppy or sideways. Traders should also be aware of the potential drawbacks of Bollinger Bands, such as false signals and over-reliance on the tool, and use other analysis methods to confirm any signals generated by the bands.

The effectiveness of Bollinger Bands will depend on the trader’s skill and experience in using the tool, as well as their ability to interpret market conditions and make informed trading decisions.

Is Bollinger Bands a good indicator?

Yes, Bollinger Bands can be a useful technical analysis tool for traders, but their effectiveness depends on several factors. Here are three pros and cons of using Bollinger Bands:

Pros:

• They can be used to identify overbought and oversold conditions and potential trend reversals.
• The upper and lower bands can be used as dynamic support and resistance levels, helping traders to manage risk and set stop-loss orders.
• Bollinger Bands can be used in conjunction with other technical indicators to confirm trading signals.

Cons:

• Bollinger Bands are a lagging indicator, which means that they do not provide timely signals for all market conditions.
• They can generate false signals in choppy or sideways markets.
• Bollinger Bands are based on standard deviation, which assumes that price movements are normally distributed, but this may not always be the case.

Bollinger bands also have their advantages and disadvantages just like any other indicator or tool used for technical analysis. It is always advised to confirm the signals with other tools to avoid unnecessary risk to the capital.

Is Bollinger Bands accurate?

Yes, Bollinger Bands can be accurate in certain market conditions and when used correctly. They can provide a visual representation of a security’s volatility and potential trading opportunities, and they can be used to identify overbought and oversold conditions, potential trend reversals, and support and resistance levels.

Traders should however, be aware of the potential drawbacks of Bollinger Bands, such as false signals and over-reliance on the tool, and use other analysis methods to confirm any signals generated by the bands.

Can Bollinger Band work well with MACD?

Yes, Bollinger Bands and the Moving Average Convergence Divergence (MACD) can work well together in technical analysis. Both indicators can provide different types of information about price movements, and when used together, they can help confirm trading signals and provide a more comprehensive analysis of the market.

Bollinger Bands can provide information about the volatility and potential trading opportunities of security, while MACD can provide information about the trend and momentum of the market. Traders can gain a better understanding of the overall market conditions and potential trading opportunities, by using both indicators together

Arjun Remesh

Head of Content

Arjun is a seasoned stock market content expert with over 7 years of experience in stock market, technical & fundamental analysis. Since 2020, he has been a key contributor to Strike platform. Arjun is an active stock market investor with his in-depth stock market analysis knowledge. Arjun is also an certified stock market researcher from Indiacharts, mentored by Rohit Srivastava.

Shivam Gaba

Reviewer of Content

Shivam is a stock market content expert with CFTe certification. He is been trading from last 8 years in indian stock market. He has a vast knowledge in technical analysis, financial market education, product management, risk assessment, derivatives trading & market Research. He won Zerodha 60-Day Challenge thrice in a row. He is being mentored by Rohit Srivastava, Indiacharts.