Bollinger Bands are a technical trading tool created by John Bollinger in the early 1980s. They arose from the need for adaptive trading bands and the observation that volatility was dynamic, not static as was widely believed at the time.
There are a number of uses for Bollinger Bands, such as determining overbought and oversold levels, as a trend following tool, and for monitoring for breakouts.
Bollinger Bands use 2 parameters, Period and Standard Deviations. The default values are 20 for period, and 2 for standard deviations, although you may customize the combinations.
The trader decides the number of standard deviations they need the volatility indicator set at. The number of standard deviations, in turn, determines the distance between the middle band and the upper and lower bands. The position of these bands provides information on how strong the trend is and the potential high and low-price levels that may be expected in the immediate future.
How to Calculate the Bollinger Bands: Bollinger Bands can be applied in all the financial markets including equities, forex, commodities, and futures. Bollinger Bands can be used in most time frames, from very short-term periods, to hourly, daily, weekly or monthly.
First, calculate a simple moving average. Next, calculate the standard deviation over the same number of periods as the simple moving average. For the upper band, add the standard deviation to the moving average. For the lower band, subtract the standard deviation from the moving average.
Typical values used:
Short term: 10 day moving average, bands at 1.5 standard deviations. (1.5 times the standard dev. +/- the SMA)
Medium term: 20 day moving average, bands at 2 standard deviations.
Long term: 50 day moving average, bands at 2.5 standard deviations.
How this indicator works?
- When the bands tighten during a period of low volatility, it raises the likelihood of a sharp price move in either direction. This may begin a trending move. Watch out for a false move in opposite direction which reverses before the proper trend begins.
- When the bands separate by an unusual large amount, volatility increases and any existing trend may be ending.
- Prices have a tendency to bounce within the bands’ envelope, touching one band then moving to the other band. You can use these swings to help identify potential profit targets. For example, if a price bounces off the lower band and then crosses above the moving average, the upper band then becomes the profit target.
- Price can exceed or hug a band envelope for prolonged periods during strong trends. On divergence with a momentum oscillator, you may want to do additional research to determine if taking additional profits is appropriate for you.
- A strong trend continuation can be expected when the price moves out of the bands. However, if prices move immediately back inside the band, then the suggested strength is negated.
Day Trading Uptrends with Bollinger Bands: Bollinger Bands can be used to determine how strongly an asset is rising and when it is potentially reversing or losing strength. If an uptrend is strong enough, it will reach the upper band regularly. An uptrend that reaches the upper band indicates that the stock is pushing higher and traders can exploit the opportunity to make a buy decision. If the price pulls back within the uptrends, and it stays above the middle band and moves back to the upper band, that indicates a lot of strength. Generally, a price in the uptrend should not touch the lower band, and if it does, it is a warning sign for a reverse or that the stock is losing strength.
Day Trading Downtrends with Bollinger Bands: Bollinger Bands can be used to determine how strongly an asset is falling and when it is potentially reversing to an upside trend. In a strong downtrend, the price will run along the lower band, and this shows that selling activity remains strong. But if the price fails to touch or move along the lower band, it is an indication that the downtrend may be losing momentum. When there are price pullbacks (highs), and the price stays below the middle band and then moves back to the lower band, it is an indication of a lot of downtrend strength. In a downtrend, prices should not break above the upper band since this would indicate that the trend may be reversing, or it is slowing.
Bollinger Bands Squeeze Strategy: A squeeze occurs when the price has been moving aggressively then starts moving sideways in a tight consolidation.
A trader can visually identify when the price of an asset is consolidating because the upper and lower bands get closer together. This means the volatility of the asset has decreased. After a period of consolidation, the price often makes a larger move in either direction, ideally on high volume. Expanding volume on a breakout is a sign that traders are voting with their money that the price will continue to move in the breakout direction.
When the price breaks through the upper or lower band, the trader buys or sells the asset, respectively. A stop-loss order is traditionally placed outside the consolidation on the opposite side of the breakout.
Conclusion: There are multiple uses for Bollinger Bands®, including using them for overbought and oversold trade signals. Traders can also add multiple bands, which helps highlight the strength of price moves. Another way to use the bands is to look for volatility contractions. These contractions are typically followed by significant price breakouts, ideally on large volume. Bollinger Bands® should not be confused with Keltner Channels. While the two indicators are similar, they are not exactly alike.