Bollinger Bands on real daily and weekly prices of bitcoin, ether, XRP and solana from the Bybit exchange: the bands, %B and Band Width, every squeeze and what came after it, and two popular band rules tested with fees.
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John Bollinger describes his formula on his own site: "an n period moving average with bands drawn above and below at intervals determined by a multiple of standard deviation (We use the population calculation for standard deviation). The defaults today are the same as they were 35 years ago, 20 periods for the moving average with the bands set at plus and minus two standard deviations of the same data used for the average."
This page follows that recipe on daily and weekly closes. Two readings come from the bands. %B shows where the close sits: TradingView gives the formula as "%b = (Current Price - Lower Band) / (Upper Band - Lower Band)", so 1 is the upper band, 0 the lower band and 0.5 the middle band. Band Width is the gap between the bands as a share of the middle band; StockCharts writes it as "( (Upper Band - Lower Band) / Middle Band) * 100".
A squeeze is a stretch of unusually narrow bands. StockCharts puts the idea this way: "The theory is that periods of low volatility are followed by periods of high volatility." The exact rule here is this page's choice: a squeeze starts on a close where Band Width is the lowest of the last 180 days (26 weeks on the weekly chart), after at least 20 days without one. The table lists every squeeze, the first close outside the bands after it, and the price change that followed.
On September 26, 2026, the last day in this data, bitcoin closed at $84,376.00. The upper band stood at $87,253.96, the middle band at $80,123.24 and the lower band at $72,992.52, for a %B of 0.80, in the upper half of the bands. Band Width was 17.8%, lower than on 55.8% of the days with bands. The latest squeeze started on July 21, 2026, and the first close outside the bands after it came on August 19, above the upper band.
Of 2,855 daily closes with bands, 87.4% were inside them, 226 were above the upper band and 133 below the lower band. On weekly closes the share inside was 85.4%. That is close to Bollinger's own experience: "In practice we typically find 90%, not 95%, of the data inside Bollinger Bands with the default parameters." The narrowest daily bands, a Band Width of 2.6%, came on August 14, 2023, and the widest, 91.1%, on March 21, 2020.
Bitcoin had 14 squeezes on the daily chart since May 31, 2019. The first close outside the bands after a squeeze was above the upper band 6 times and below the lower band 8 times, so the squeeze itself gave no hint of the direction. The moves that followed were a little larger than usual: the median move over the next 30 days, up or down, was 13.5% after a squeeze, against 11.1% from every day with bands, and over 90 days 24.9% against 22.3%.
The other coins do not back the theory as clearly. Over 30 days the median move after a squeeze was 18.0% for ether, against 14.8% on all days, but 10.6% for XRP against 13.1%, and 9.9% for solana against 16.8%. With only 8 to 14 squeezes per coin, these samples are small.
Bollinger's own rules warn against reading every touch of a band as a signal: "Tags of the bands are just that, tags not signals," and "Closes outside the Bollinger Bands are initially continuation signals, not reversal signals." The test puts both ideas on real prices, starting with $10,000 on December 4, 2018 and trading at the next day's open with a 0.1% fee and 0.05% slippage per trade.
On the other coins the breakout rule finished ahead of buying and holding for XRP and solana and behind it for ether. The reversion rule trailed buying and holding on all four coins.
The bitcoin RSI page measures momentum on the same closes, and what is market volatility explains why prices swing.
Educational, not financial advice. Bollinger Bands describe how past prices moved. They do not predict the next move or recommend buying or selling any coin.
At the last close in this data, September 26, 2026, the 20-day bands were $87,253.96 (upper), $80,123.24 (middle) and $72,992.52 (lower), with bitcoin at $84,376.00. That is a %B of 0.80 and a Band Width of 17.8%.
The middle band is the simple average of the last 20 closes. The upper and lower bands sit two standard deviations of those same 20 closes above and below it; John Bollinger uses the population standard deviation. %B is (close - lower band) / (upper band - lower band), and Band Width is (upper band - lower band) / middle band.
A period when the bands are unusually narrow, which means prices have been calm. On this page a squeeze starts when Band Width closes at its lowest level of the last 180 days. Bitcoin had 14 since May 2019; the first close outside the bands afterwards was above the upper band 6 times and below the lower band 8 times.
Not by itself. John Bollinger writes that "A tag of the upper Bollinger Band is NOT in-and-of-itself a sell signal." In this data, buying bitcoin on closes below the lower band and selling at the middle band lost money after fees, while buying closes above the upper band made money but trailed buying and holding.
%B places the close within the bands: 1 is the upper band, 0.5 the middle band and 0 the lower band. Values above 1 or below 0 mean the close was outside the bands. Bitcoin's %B at the last close in this data was 0.80.