# Acceleration Bands A Volatility concept (Band & channel systems) in the LuxAlgo Library, with 1 indicator implementation. ## What are acceleration bands? Acceleration bands are a price envelope developed by Price Headley in which the band width at each bar is driven by that bar's own high-low range, normalized by its midpoint. The upper band is a moving average of highs pushed up in proportion to the bar's relative range, and the lower band is a moving average of lows pushed down the same way, typically over 20 periods with a simple moving average of the close as the midline. The design reflects Headley's premise that the strongest moves accelerate: when price closes outside the bands for consecutive bars, the move is expanding faster than its own recent range structure, which he treated as evidence of a genuine directional breakout rather than noise. That is the opposite orientation of many band systems, where a touch of the outer band is read as stretched. Acceleration bands were built as a breakout tool first. Traders care because the range-proportional construction makes the bands widen on volatile bars and hug price on quiet ones without relying on a standard-deviation window the way [Bollinger Bands](https://www.luxalgo.com/library/concept/bollinger-bands/) do, or on an ATR multiple the way [Keltner Channels](https://www.luxalgo.com/library/concept/keltner-channels/) do. The behavior sits somewhere between an [envelope](https://www.luxalgo.com/library/concept/envelope/) and a volatility channel. ## How it's calculated The standard published form uses a 20-period simple moving average and a scaling factor of 4: ``` Upper = SMA(n) of (high * (1 + 4 * (high - low) / (high + low))) Lower = SMA(n) of (low * (1 - 4 * (high - low) / (high + low))) Midline = SMA(n) of close n: lookback period (default 20) high, low: the bar's high and low 4: the band scaling factor in the standard form; some platforms expose it as a parameter ``` The term (high - low) / (high + low) is half the bar's range expressed as a fraction of its midpoint, so wide bars push the bands apart before averaging. ## How traders use it - Breakout entries: the classic rule takes a position after two consecutive closes outside a band, treating the acceleration as the start of a strong leg; a close back inside the band is the standard exit. - Trend riding: while price keeps closing beyond or near the outer band, the move is considered in its acceleration phase, a behavior closely related to a [band walk](https://www.luxalgo.com/library/concept/band-walk/). - Midline management: the 20-period midline serves as a trailing reference for partial exits once the acceleration fades. - With honest limits: like all breakout logic, consecutive closes outside the bands occur at the end of moves too, so many users add volume or momentum confirmation and accept whipsaws in ranging markets. ## Acceleration bands vs other band systems - **Bollinger Bands** (https://www.luxalgo.com/library/concept/bollinger-bands/): Bollinger Bands scale by the standard deviation of closes over the window; acceleration bands scale each bar by its own normalized range before averaging, and are conventionally traded as breakout signals rather than reversion references. - **Keltner Channels** (https://www.luxalgo.com/library/concept/keltner-channels/): Keltner Channels offset a moving average by a multiple of ATR, producing smoother, steadier width. Acceleration bands respond bar by bar to range, so they flare faster on volatile bars. - **Donchian Channels** (https://www.luxalgo.com/library/concept/donchian-channels/): Donchian Channels mark the raw n-bar extreme, so price can never close outside them until a new extreme prints. Acceleration bands sit inside recent extremes often enough for closes beyond them to be a usable signal. ## FAQ ### What settings are standard? A 20-period SMA with the factor of 4 is the published default. Shorter windows make the bands jumpier; changing the factor mainly shifts how often price closes outside. ### Are acceleration bands mean-reversion tools? Not as designed. Headley's usage treats closes outside the bands as breakout strength. Some traders do fade single tags in ranges, but that is a repurposing, not the original logic. ### How is the two-closes rule typically confirmed? Common filters include rising volume on the breakout bars, alignment with a higher-timeframe trend, and general [breakout confirmation](https://www.luxalgo.com/library/concept/breakout-confirmation/) practice such as holding beyond the broken level. ### Do they work intraday? The construction is timeframe-agnostic, but intraday bars have noisier ranges, so many users lengthen the window or demand extra confirmation on lower timeframes. ## Implementations in the Library - Acceleration Bands (LuxAlgo): https://www.luxalgo.com/library/indicator/acceleration-bands/ ## Related concepts - Donchian Channels: https://www.luxalgo.com/library/concept/donchian-channels/ - Envelope: https://www.luxalgo.com/library/concept/envelope/ - Bollinger Bands: https://www.luxalgo.com/library/concept/bollinger-bands/ - %B: https://www.luxalgo.com/library/concept/percent-b/ - BandWidth: https://www.luxalgo.com/library/concept/bandwidth/ - Bollinger Squeeze: https://www.luxalgo.com/library/concept/bollinger-squeeze/ - Band Walk: https://www.luxalgo.com/library/concept/band-walk/ - Bollinger Band Tag Reversion: https://www.luxalgo.com/library/concept/bollinger-band-tag-reversion/ - Double Bollinger Zones: https://www.luxalgo.com/library/concept/double-bollinger-zones/ - Fibonacci Bollinger Bands: https://www.luxalgo.com/library/concept/fibonacci-bollinger-bands/ --- Source: https://www.luxalgo.com/library/concept/acceleration-bands/ (LuxAlgo Library, the encyclopedia of trading & technical analysis). Free to use with attribution: https://www.luxalgo.com/library/license/