Bollinger Bands

• Bollinger Bands consist of three lines: a middle band (the 20-period simple moving average) and two outer bands placed two standard deviations above and below it. The outer bands expand and contract with volatility.
• When the bands narrow into a squeeze, volatility is contracting and the market is building energy for the next move. When the bands expand, a directional move is underway.
• Price touching an outer band is not a signal on its own. Context, trend direction, and confirmation from other tools determine whether the touch is a continuation or a warning.

Bollinger Bands are a volatility indicator placed directly on the price chart, made up of three lines that move together as market conditions change. The middle band is a 20-period simple moving average. The upper band sits two standard deviations above that average. The lower band sits two standard deviations below it.

If you are new to reading technical indicators on a chart, start with Introduction to Charts before continuing.

Standard deviations measure how far price has been moving away from the average. When price is moving a lot, the standard deviation is high and the outer bands expand. When price is quiet and contained, the standard deviation is low and the bands contract. The bands do not stay still. They breathe in and out with the market.

Developed by John Bollinger in the 1980s, the indicator was built around one central idea: price is high relative to its recent range when it is near the upper band, and low relative to its recent range when it is near the lower band. That relative reading is more useful than an absolute price level because it accounts for whether the market is currently volatile or quiet.

The Middle Band

The 20-period SMA running through the centre of the indicator is not just a reference line. It acts as a dynamic support and resistance level in its own right. When price holds consistently above the middle band, bullish conditions dominate. When price holds below it, bearish conditions dominate. A close back through the middle band from above is often the first warning that momentum is fading. In a downtrend, the same line acts as resistance on any recovery attempt.

The Upper Band

The upper band represents statistically elevated price levels relative to recent history. A touch or close outside the upper band does not mean price must reverse lower. In a strong uptrend, price can walk along the upper band for an extended period without reversing. The upper band marks where price is stretched, not where it is forbidden to go.

The Lower Band

The lower band represents statistically depressed price levels. The same principle applies in reverse. In a strong downtrend, price can remain near or outside the lower band for far longer than most traders expect. A touch of the lower band in a falling market is not an automatic reason to buy.

The Bollinger Band Squeeze

When the bands narrow sharply and remain close together over several sessions, it is called a squeeze. A squeeze does not tell you which direction the next move will go. It tells you that a significant move is coming. The compression of volatility that precedes a breakout is the market loading before it fires. Experienced traders watch for the squeeze and prepare to respond when the bands begin to expand, rather than trying to anticipate the direction in advance.

Bollinger Band Expansion

When the bands widen aggressively, volatility is increasing and momentum is strengthening. Expansion typically occurs during news events, breakouts, and trend acceleration phases. A close beyond one of the outer bands with expanding bands behind it confirms the move is genuine. High-impact news releases in particular frequently trigger sharp band expansion. During these moments, the bands can widen rapidly within a single session and equally reverse, which is why entering during a news-driven expansion carries more risk than entering during a structural breakout.

Bollinger Bands in Trending Markets

This is where most beginners go wrong. In a strong uptrend, price can repeatedly touch or ride the upper band without reversing. In a strong downtrend, it can ride the lower band for the same reason. Selling every upper band touch in a bull trend and buying every lower band touch in a bear trend fails badly in trending conditions. Recognising whether the market is trending or ranging is more important than reading the band touches themselves.

Mean Reversion

Outside of trending conditions, price tends to return to the middle band after touching an outer one. In a ranging market, the upper band acts as a selling reference and the lower band acts as a buying reference, with the middle band as the natural target for both. This tendency is reliable in low-volatility, sideways conditions but breaks down quickly when a trend is underway. Applying it during a trend produces trades that work against momentum.

Double Bollinger Bands

More experienced traders sometimes plot two sets of bands simultaneously, one at one standard deviation and one at two standard deviations from the middle band. The space between the inner and outer sets creates distinct zones. Price holding between the one and two standard deviation bands on the upper side signals a strong uptrend. Price falling below the one standard deviation band on the lower side signals weakening momentum. This is an advanced application and not necessary at this stage, but worth knowing as the indicator develops in your toolkit.

EUR/USD entered a clear Bollinger Band squeeze in early May 2026, following the sharp rally through April. Here is how the bands were positioned on 8 May 2026:

The April rally from 1.1411 had pushed the bands wide as volatility expanded. By early May, price had settled into a range between 1.1670 and 1.1795, and the outer bands were visibly contracting.

The squeeze did not identify whether the breakout would go up or down. It identified that a breakout was building. A sustained close beyond either boundary, confirmed by expanding bands and momentum, would determine the direction of the next move.

Most technical indicators tell you about price direction or momentum. Bollinger Bands tell you about the state of the market itself. A narrow, quiet set of bands means something different from wide, expanding bands even if the price level is the same. That context changes what every other signal you read should mean.

The bands also give you structural references for stop placement. If you are entering a trade near the lower band, a logical stop sits just beyond the lower band itself. If you are entering near the upper band in a short setup, the stop goes just beyond the upper band. The band gives you an objective structural level rather than an arbitrary number, and that reference adjusts with each session as volatility changes.

When price is trading above the 200-period SMA, bullish signals at the lower band carry more weight. When price is below it, bearish signals at the upper band carry more weight. The same filter from the Moving Averages article applies here. Bollinger Bands give you the volatility picture. The 200-period SMA gives you the broader structural bias.

The indicator also works well alongside momentum tools. A price touching the upper band while the RSI is above 70 in a ranging market is a meaningful combination for a mean reversion setup. The same touch while the MACD histogram is expanding bullishly in a trend suggests something entirely different. The band gives you volatility context. Momentum tells you whether buyers or sellers have conviction. For a deeper look at how to use volatility context in trade protection and position sizing, read Risk Management alongside this topic.

1. Bollinger Bands consist of a 20-period SMA flanked by two outer bands set two standard deviations above and below. Wide bands signal high volatility. Narrow bands signal low volatility and an impending move.
2. A squeeze occurs when the bands contract sharply. It signals that energy is building for the next significant move but does not indicate direction. A breakout from the squeeze, confirmed by expanding bands and momentum, is the signal to act on.
3. Price walking along an outer band signals a strong trend. Price bouncing between the outer bands signals a range. Knowing which condition the market is in determines how to use every touch of the bands.

You can now read volatility alongside direction and momentum. The next step is learning how to identify the larger structural formations that form across multiple sessions and reveal the market's broader intentions.

• [Chart Patterns] – Learn how head and shoulders, double tops, triangles, and other multi-session formations signal where the next significant move is likely to come from, and how to combine them with everything you have learned so far.
• [MACD] – See how Bollinger Bands and the MACD work together to confirm breakout signals, and how expanding bands alongside a MACD crossover produce one of the cleaner setups in technical analysis.

Open a daily chart on any major currency pair and add Bollinger Bands with the default 20-period, 2 standard deviation settings. Look back over the past three months and identify at least one period where the bands narrowed into a squeeze and one where they expanded during a strong move. Note what price did after each squeeze resolved. Then observe how price behaved when it touched the outer bands during trending versus ranging conditions. Practice identifying Bollinger Band setups on a demo account before applying them in live trading.