Bollinger Bands Explained: Breakouts, Squeezes & How to Scan for Them
Bollinger Bands are one of the most versatile tools in technical analysis. They wrap price in a dynamic envelope that expands and contracts with volatility, which makes them useful for spotting breakouts, mean reversion, and quiet periods that often precede big moves. Here is how they actually work and how to put them to use across the crypto market.
What Bollinger Bands are
A Bollinger Band set has three lines:
- Middle band — a simple moving average of price (commonly 20 periods).
- Upper band — the middle band plus a number of standard deviations (commonly 2).
- Lower band — the middle band minus that same number of standard deviations.
Because standard deviation is a measure of volatility, the bands widen when the market is volatile and narrow when it is calm. That self-adjusting nature is what sets them apart from fixed channels.
Reading the bands
There are two classic, almost opposite, ways traders use them:
Mean reversion (in ranges). When price tags the upper band it is statistically stretched to the upside, and vice versa for the lower band. In a sideways market, touches of the bands often precede a snap back toward the middle.
Breakouts (in trends). A close beyond a band is not automatically a reversal — in a strong trend it signals momentum. Price can "walk the band", riding the upper edge higher for a long time. This is the basis of the band-breakout signals: a close above the upper band flags upside expansion, a close below the lower band flags a breakdown.
The key question, as always, is range or trend? The same band touch means opposite things in each regime.
The Bollinger squeeze
The most famous Bollinger setup is the squeeze: when the bands contract to an unusually narrow width, volatility has dried up. Markets alternate between calm and active, so a tight squeeze often precedes a sharp expansion — though it does not tell you the direction. Traders watch a squeeze and then trade the breakout when price finally closes decisively beyond a band.
Bollinger Band Width (BBW) turns this into a number: it measures the distance between the bands relative to the middle. A BBW near multi-month lows is a squeeze worth watching.
Period and standard deviation
Two settings shape the bands:
- Period — a short lookback (e.g. 14) hugs price tightly and reacts fast; a long one (e.g. 50 or 200) is smoother and frames the bigger picture. Comparing a fast band to a slow band is a neat way to gauge whether short-term volatility is expanding past the long-term baseline.
- Standard deviations — 2 is standard and contains roughly 95% of price action. Lower it (e.g. 1.25) and breakouts trigger more often but with more noise.
How to scan for Bollinger setups
Rather than eyeballing charts, define the rule in the crypto screener:
- Breakout: condition
Price (close) is above BB upper band— find coins breaking out right now. - Breakdown:
Price (close) is below BB lower band. - Expansion: compare two bands, e.g.
BB(14) upper above BB(200) upper, to catch volatility waking up.
Or skip the build and watch the live Bollinger breakout signals, refreshed every four hours across 1,000+ Binance pairs and five timeframes.
Key takeaways
- Bollinger Bands = a moving average ± standard deviations; they breathe with volatility.
- Band touches mean reversion in ranges but momentum in trends — identify the regime first.
- The squeeze (narrow bands / low BBW) often precedes a big move, direction unknown.
- Scan the whole market for breakouts and squeezes instead of one chart at a time.