What are Bollinger Bands?
Written by an ex-institutional trader. What Bollinger Bands are, shown with a diagram, how the bands measure volatility, what the squeeze and band touches mean, and how to use them without the classic beginner trap.
Direct answer
Bollinger Bands are a volatility indicator made of three lines: a middle moving average (usually 20 periods) and an upper and lower band set two standard deviations above and below it. The bands widen when volatility rises and narrow when it falls, so they show at a glance how active or quiet a market is, while wrapping around price to frame where it is trading relative to its recent range.
The most useful signals are the squeeze, when the bands narrow sharply and often precede a big move, and the way price tends to spend most of its time inside the bands. The classic beginner trap is treating a touch of the upper band as an automatic sell and the lower band as a buy; in a strong trend, price can ride a band for a long time. Bollinger Bands work best read alongside the trend and other signals, not as a standalone system.
What Bollinger Bands are
Bollinger Bands are a volatility indicator developed by John Bollinger in the 1980s. They wrap three lines around price: a middle moving average, usually 20 periods, and an upper and lower band set two standard deviations above and below it. Because standard deviation measures how much price is moving, the bands automatically widen when volatility rises and narrow when it falls.
That gives two readings at once: how volatile the market is (band width) and where price sits relative to its recent range (its position between the bands). It is one of the most popular indicators precisely because it shows both in a single, intuitive picture.
Disclosure: SatoshiMacro may earn a commission if you open a broker account through links on this page, at no extra cost to you. See our full affiliate disclosure.
The three bands
The diagram below shows the structure: a middle moving average with an upper and lower band that breathe in and out with volatility. Notice how the bands narrow during the quiet stretch (the squeeze) and widen as the move expands, with price spending most of its time inside them.
Roughly 90 percent of price action stays within the bands, which is why a move that pushes hard against or outside a band stands out: it signals an unusually strong push, which may either mark an extreme or, in a trend, confirm strength.
The squeeze
The squeeze is the signal Bollinger Bands are best known for. When the bands narrow sharply, volatility has dropped and the market has gone quiet, often coiling before a larger move. The logic is that markets cycle between low and high volatility, so an unusually tight squeeze tends to be followed by expansion.
The catch is that the squeeze does not tell you direction. It flags that a big move may be coming, not which way. Traders use it as a heads-up to prepare, then take the directional cue from the breakout itself and from other signals like the trend and momentum. Squeezes are especially useful in the quiet before a major economic release.
How to use them
A few sound ways to read the bands:
- Volatility context. Wide bands mean an active, possibly trending market; narrow bands mean a quiet one. This alone helps you pick the right strategy for conditions.
- Riding the band in a trend. In a strong uptrend, price walking up the upper band confirms strength rather than signalling a sell. The same applies in reverse for downtrends.
- Mean reversion in a range. In a sideways market with flat bands, touches of the upper and lower bands can mark the edges of the range, used the same way as support and resistance.
The right use depends entirely on whether the market is trending or ranging, which the band width itself helps you judge.
Common mistakes
The classic Bollinger Band errors:
- Selling every upper-band touch. In a trend, price rides the band. This is the single most common mistake and a direct way to fight a strong move.
- Trading the squeeze blind. A squeeze signals a move is likely, not its direction. Wait for the breakout.
- Ignoring the trend. Mean-reversion tactics work in ranges, not trends. Read band width to tell which you are in.
- Skipping risk management. As always, the position size and stop protect the account, not the indicator.
Read with the trend and confirmed by price, Bollinger Bands give a strong volatility read. Build the rest of the foundation with RSI, moving averages and support and resistance, and choose a broker with full charting from the best forex brokers in Australia ranking.
Popular ASIC-regulated CFD brokers
All three are ASIC-regulated with free demo accounts. CFD Service. Your capital is at risk.
Diagram is illustrative. Last reviewed: 2026-06-01.
Frequently asked questions
What are Bollinger Bands in simple terms?
Bollinger Bands are three lines plotted around price to show volatility and relative price level. The middle line is a moving average, usually 20 periods, and the upper and lower lines sit two standard deviations above and below it. Because standard deviation measures volatility, the bands widen when the market is moving a lot and narrow when it is quiet. They give a quick visual read of whether price is high or low relative to its recent range, and whether volatility is rising or falling.
What does the Bollinger Band squeeze mean?
A squeeze is when the bands narrow sharply because volatility has dropped, signalling a quiet, coiled market. Squeezes often precede a significant move, because periods of low volatility tend to be followed by high volatility, though the squeeze itself does not tell you which direction the breakout will go. Traders watch a squeeze as a heads-up that a big move may be coming and then take their directional cue from the breakout and other signals, not from the squeeze alone.
Should I sell when price hits the upper Bollinger Band?
Not automatically. A touch of the upper band means price is high relative to its recent range, but in a strong uptrend price can hug or ride the upper band for a long time while continuing to rise. Selling every upper-band touch is the most common Bollinger Band mistake and a good way to fight a trend. Band touches are better used as context, confirmed by the trend and a reversal signal, rather than as standalone buy or sell triggers.
What are the best Bollinger Band settings?
The standard settings, set by John Bollinger who created the indicator, are a 20-period simple moving average with bands at two standard deviations. These work across timeframes and markets and are what almost all charts default to. Some traders widen the deviation to 2.5 for less frequent signals or shorten the average for more sensitivity, but the defaults are well chosen and most traders should leave them alone and focus on reading the bands in context.
Do Bollinger Bands work in forex?
Yes, Bollinger Bands are widely used in forex and CFD trading because currency pairs move through clear cycles of high and low volatility that the bands capture well. The squeeze is especially useful around quiet periods before major economic releases, and band width gives a quick read of whether a pair is trending or ranging. As in any market, they work best combined with the trend and other tools rather than as a standalone signal, and always with defined risk.
What is the difference between Bollinger Bands and Keltner Channels?
Both wrap bands around a moving average, but they measure width differently. Bollinger Bands use standard deviation, so they expand and contract with volatility, which makes the squeeze possible. Keltner Channels use average true range, which tends to make them smoother and less reactive. Some traders combine the two, watching for when the narrower Bollinger Bands pull inside the Keltner Channels as a stricter squeeze signal. For most traders, standard Bollinger Bands alone are enough to start.
