Volatility indicator
Bollinger Bands Calculator
Compute the upper and lower Bollinger Bands from a moving average, its standard deviation, and a multiplier. The idea behind them, an envelope that breathes with volatility, is the part worth understanding.
What Bollinger Bands are
Bollinger Bands, developed by John Bollinger in the 1980s, wrap a moving average in an envelope that expands and contracts with volatility. The middle band, called the basis, is a simple moving average of price, by default over 20 periods. The upper and lower bands sit a set number of standard deviations away from the basis, by default two.
Standard deviation measures how far prices have spread around their average over the window. Because it grows when price swings widen and shrinks when they settle, the bands automatically widen in volatile conditions and pinch together in quiet ones. The bandwidth figure above expresses the gap between the bands as a percentage of the basis, a common way to compare volatility across different periods.
Why Bollinger Bands are used
Bollinger Bands are used to place price in the context of recent volatility. Analysts often note when price rides along the upper or lower band, when the bands squeeze to unusually narrow widths, and how far price strays from the basis before returning toward it. John Bollinger himself stressed that touching a band is not itself a signal, only information.
The 20-period, two–standard-deviation defaults are conventions, and the appropriate settings depend on the market and timeframe. Any interpretation is your own.
What are TradingView and Pine Script?
TradingView is one of the most widely used charting and market-analysis platforms, where traders and analysts study price movement across stocks, crypto, forex, and futures on interactive charts. Pine Script is TradingView's own lightweight programming language, created so anyone can build custom tools that run directly on those charts.
People use Pine Script to build four main kinds of tools. Indicators calculate and plot values on the chart, exactly like the calculation above, but recomputed automatically on every bar. Strategies add explicit entry and exit rules and can be backtested against historical data in TradingView's Strategy Tester to see how they would have behaved. Screeners scan many symbols at once for conditions you define. Alerts notify you the moment a condition you specified occurs, so you do not have to watch the screen.
The value is precision and automation. Instead of eyeballing a chart, you describe exactly what you want measured, visualized, or notified about, and TradingView runs it consistently across any market and timeframe. That is why traders, analysts, and developers write Pine Script: it turns a manual charting idea into a repeatable tool. These tools are for tracking, visualizing, and testing market ideas; they do not tell you what to trade, and that decision always remains yours.
Writing that code by hand means learning Pine Script's syntax, its type system, and the exact names of hundreds of built-in functions. It is a real programming language, and small mistakes stop a script from compiling in the Pine Editor.
Turn this into Pine Script
This calculator gives you one set of band values. On a chart the three bands recalculate every bar and are usually drawn with a shaded fill between them. Pine Script returns all three from a single call, ta.bb(close, 20, 2), but the plotting, fills, squeeze detection, and any alerts around them still need to be written.
//@version=6
indicator("Bollinger Bands", overlay=true)
[middle, upper, lower] = ta.bb(close, 20, 2)
plot(middle, "Basis", color=color.orange)
p1 = plot(upper, "Upper", color=color.blue)
p2 = plot(lower, "Lower", color=color.blue)
fill(p1, p2, color=color.new(color.blue, 90))PineScripter is an AI built specifically for Pine Script. You describe what you want in plain English and it writes TradingView-ready v5 or v6 code. Because it is specialized on the Pine Script language and its exact function signatures, it tends to produce code that compiles far more reliably than general-purpose models like ChatGPT, which often invent functions that do not exist in Pine Script.
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PineScripter is an AI developer tool that helps you write Pine Script code. It is not a financial advisor and will never offer financial, investment, or trading advice. Everything on this page, including the calculator and the explanations, is provided purely for educational and informational purposes. Any decision about how to interpret an indicator or trade a market is entirely your own. See our full disclaimer for more.