Some indicators try to tell you where price is going. Bollinger Bands do something more modest and, arguably, more useful: they show you how stretched price is compared with its own recent behaviour. Once you see them that way, a lot of the confusion around them disappears.
How the bands are built
Bollinger Bands were developed by John Bollinger in the 1980s. They have three parts. In the middle sits a simple moving average, usually covering 20 periods. Above and below it sit two outer bands, normally set two standard deviations away from that average.
Standard deviation sounds intimidating, but the idea is simple. It is a measure of how widely prices have been spread around their average. When prices have been jumping about, the standard deviation is large and the bands sit far apart. When prices have been drifting quietly, the standard deviation shrinks and the bands pull in tight.
If the middle line is new to you, our guide to moving averages for beginners covers the building block underneath it.
What the width is telling you
The most honest thing Bollinger Bands show is volatility. Wide bands mean the market has been moving a lot. Narrow bands mean it has been calm.
Traders pay particular attention to the moment when the bands become unusually narrow, often called a squeeze. A squeeze describes a market that has gone quiet. It does not tell you which way the next move will go, and it does not promise that a move is imminent. It simply says that conditions have been compressed, and compressed conditions often give way to livelier ones at some point.
That is why a squeeze is better treated as a reason to pay attention than as a reason to act. Our explainer on volatility in trading goes deeper on why quiet spells and busy spells tend to alternate.
Touching the band is not a signal on its own
A common beginner habit is to treat a touch of the upper band as a sign that price must fall, and a touch of the lower band as a sign that it must rise. It is an understandable instinct, because the bands look like walls. They are not walls.
In a strong trend, price can travel along the upper band for days or even weeks. Each touch looks stretched, yet the move carries on. The same is true on the downside. Selling every upper-band touch in a rising market can turn into a long run of small, frustrating losses.
A more balanced reading is that a band touch tells you price is at the edge of its recent range. Whether that edge holds depends on the wider context: the trend, the news backdrop and where the obvious support and resistance levels sit.
Two ways traders tend to use them
Broadly, people use Bollinger Bands in one of two ways.
In ranging markets, some traders look at moves to the outer bands as possible areas where price might pause or turn back towards the middle line. This approach relies on the market staying range-bound, which is never guaranteed.
In trending markets, other traders watch for price holding near one band as evidence that the trend still has energy. Here the middle line often acts as a rough guide to whether the trend is intact.
The mistake is mixing the two without noticing which kind of market you are in. A range-trading approach in a trending market, or the reverse, is where most of the pain comes from.
Settings and timeframes
The default 20-period average and two standard deviations were designed for daily charts. Many traders apply them to shorter timeframes, which produces far more band touches and much more noise. Changing the settings is fine, but tweaking them until they fit last month’s chart perfectly is a quick route to a method that fails on next month’s.
A sensible approach is to pick settings, stick with them while you learn how they behave, and judge them over a meaningful number of examples rather than a handful.
Keep risk in charge
No indicator removes the need for a plan. Before acting on anything you see in the bands, you should know where you would be wrong, how much you are prepared to lose and how large the position should be. The bands can help describe the market. They cannot manage your risk for you.
If you would like a clearer picture of how your own chart reading and risk habits compare with a structured approach, our free trader assessment is a good place to start, and it only takes a few minutes.
