Bollinger Bands — Volatility Envelopes
Overview
Bollinger Bands plot a moving average with upper and lower bands set at 2 standard deviations, expanding during high volatility and contracting during low volatility to create actionable squeeze and breakout signals. The Bollinger Squeeze is especially powerful when combined with Keltner Channels in the TTM Squeeze setup, a favourite of professional traders. Pair Bollinger Bands with the RSI to filter false signals and confirm breakout entries. Set them up on TradingView for real-time alerts and multi-timeframe analysis.
How It Works
Middle band = 20-period SMA. Upper band = SMA + (2 × standard deviation). Lower band = SMA − (2 × standard deviation). Approximately 95% of price action falls within the bands under normal distribution.
Key Signals
- A Bollinger Squeeze (narrow bands) precedes explosive moves in either direction.
- Price touching the upper band isn't automatically overbought in an uptrend.
- Walking the band (price hugging upper or lower band) confirms strong trend momentum.
- W-bottoms and M-tops within the bands are classic reversal patterns.
Common Mistakes
- Selling when price touches the upper band in a strong uptrend — it's a sign of strength.
- Using Bollinger Bands alone for entry — always combine with RSI or volume.
- Not recognizing squeezes — the longer the squeeze, the bigger the breakout.
More Volatility Indicators
ATR — Average True Range
ATR measures market volatility by calculating the average range of price bars over a specified period — it is essential for position sizing, stop-loss placement, and identifying volatility shifts. Use our <a href="/tools/calculators/position-size" class="text-primary hover:underline">position size calculator</a> to convert ATR readings into proper trade sizing instantly. Read the <a href="/guides/use-stop-loss-orders" class="text-primary hover:underline">stop-loss guide</a> and the <a href="/guides/calculate-position-size" class="text-primary hover:underline">position sizing guide</a> to master ATR-based risk management across every market. ATR adapts to any asset — apply it in <a href="/market/crypto" class="text-primary hover:underline">crypto</a>, <a href="/market/stocks" class="text-primary hover:underline">stocks</a>, and <a href="/market/forex" class="text-primary hover:underline">forex</a> for volatility-adjusted trading.
Ulcer Index
The Ulcer Index measures downside volatility by calculating the depth and duration of drawdowns from recent highs, providing a risk metric that focuses exclusively on the pain investors care about most. It was created by Peter Martin specifically for evaluating <a href="/market/stocks" class="text-primary hover:underline">stock</a> fund performance. Incorporate the Ulcer Index into your risk management alongside tools from our <a href="/academy/indicators" class="text-primary hover:underline">indicator guide library</a> to protect capital during volatile markets.
Chaikin Volatility
Chaikin Volatility measures the rate of change of the difference between high and low prices, providing a unique view of how the trading range is expanding or contracting. Unlike <a href="/academy/indicators/atr" class="text-primary hover:underline">ATR</a>, which smooths absolute range, Chaikin Volatility focuses on the acceleration of range changes. It is useful in <a href="/market/stocks" class="text-primary hover:underline">stock</a> and <a href="/market/forex" class="text-primary hover:underline">forex</a> markets and can be explored alongside other volatility tools in our <a href="/academy/indicators" class="text-primary hover:underline">indicator guide library</a>.
Standard Deviation
Standard Deviation measures the dispersion of closing prices from their mean over a given period, providing the mathematical foundation for <a href="/academy/indicators/bollinger-bands" class="text-primary hover:underline">Bollinger Bands</a> and many other volatility tools. Rising standard deviation signals increasing volatility across <a href="/market/stocks" class="text-primary hover:underline">stocks</a>, <a href="/market/crypto" class="text-primary hover:underline">crypto</a>, and <a href="/market/forex" class="text-primary hover:underline">forex</a>. Review our <a href="/academy/indicators" class="text-primary hover:underline">indicator guide library</a> to see how standard deviation powers multiple volatility-based trading tools.