Bollinger Bands (Quick Answer)
Bollinger Bands measure volatility around a moving average using standard deviation.
They help traders spot overbought/oversold conditions, potential mean reversion, and volatility expansion setups like the
Bollinger Squeeze.
TL;DR
- Upper band = often “overbought” zone (context matters)
- Lower band = often “oversold” zone (context matters)
- Band squeeze = volatility compression that can precede a big move
- Default settings: 20 SMA with 2 standard deviations
Traders and investors use Bollinger Bands to assess expected price action in financial markets.
Bollinger Bands are a popular technical tool plotted at a standard deviation above and below a simple moving average.
When used correctly, they can help identify when a stock is stretched (overbought/oversold) and when volatility is about to expand.
I don’t say this lightly: using Bollinger Bands effectively is necessary for serious technical traders.
Famous analyst John Bollinger developed Bollinger Bands in the early 1980s and trademarked the term in 2011. The goal was to define a volatility “envelope” around price—so traders can estimate a realistic range where price is likely to travel.
Three lines comprise Bollinger Bands: the lower, the middle, and the upper. The middle line is typically a 20-day simple moving average (SMA). The upper and lower bands expand/contract based on volatility (standard deviation). You can customize the settings depending on your market and timeframe. See the breakdown below.
Famous analyst John Bollinger developed Bollinger Bands in the early 1980s and trademarked the term in 2011. The goal was to define a volatility “envelope” around price—so traders can estimate a realistic range where price is likely to travel.
Three lines comprise Bollinger Bands: the lower, the middle, and the upper. The middle line is typically a 20-day simple moving average (SMA). The upper and lower bands expand/contract based on volatility (standard deviation). You can customize the settings depending on your market and timeframe. See the breakdown below.
Bollinger Band Calculations
First, calculate a simple moving average. Next, calculate the standard deviation over the same number of periods as the moving average.
The upper band is the middle band plus a multiple of standard deviation. The lower band is the middle band minus a multiple of standard deviation.
Typical values used:
Typical values used:
- Short-term: 10-day moving average, bands at 1.5 standard deviations.
- Medium-term: 20-day moving average, bands at 2 standard deviations.
- Long-term: 50-day moving average, bands at 2.5 standard deviations.
Backtest Bollinger Bands (Stop Guessing Settings)
Bollinger Bands are powerful, but results vary by ticker, timeframe, and volatility regime.
If you want to use them professionally, you should backtest your band settings and build rules you can repeat.
My preferred platform for fast testing and clean charting is:
TrendSpider
(exclusive discount code via the link).
Disclosure: This is an affiliate link. If you use it, I may earn a commission at no extra cost to you.
How To Trade Bollinger Bands Effectively
The most common use is identifying overbought and oversold conditions:
- If price touches or rides the upper band, it can be overbought and due for a pullback (especially if it pierces hard).
- If price touches or rides the lower band, it can be oversold and due for a bounce (but bounces are not guaranteed—context matters).
Check out this Lucid Motors example, where price pushed aggressively above the upper band—hinting at a pullback that followed quickly:
Important: Different traders apply Bollinger Bands differently.
Some buy near the lower band and take profits near the middle band.
Others trade band “breaks” (momentum) and exit on a reclaim or failure.
One thing to watch: prices can snap back fast after a band touch—especially when the bands are tight and volatility is low. That leads into the Bollinger Squeeze.
One thing to watch: prices can snap back fast after a band touch—especially when the bands are tight and volatility is low. That leads into the Bollinger Squeeze.
What Is a Bollinger Squeeze?
When the bands tighten, volatility is compressing. In many markets, low volatility doesn’t last forever.
A squeeze can foreshadow a sharp move—either direction.
The mistake beginners make is assuming a squeeze is automatically bullish. It’s not. It’s a volatility warning. Direction should be confirmed with trend, volume, and/or a catalyst.
The mistake beginners make is assuming a squeeze is automatically bullish. It’s not. It’s a volatility warning. Direction should be confirmed with trend, volume, and/or a catalyst.
Simple Bollinger Bands Rules (Good Starting Point)
- Mean reversion setup: fade extreme pushes outside the bands only when trend is weakening or momentum stalls.
- Trend setup: in strong trends, price can “ride” the upper band for days—don’t short it blindly.
- Squeeze setup: treat tight bands as an alert; wait for confirmation (break + follow-through + volume).
- Risk management: define exits before entry (stops and targets), because band touches can fail.
Conclusion
The beauty of Bollinger Bands is probabilistic: with standard settings, price spends most of its time within the bands.
When price stretches far outside, it often reverts (not always immediately, but often).
Capturing high-probability reversals—and knowing when not to fade a strong trend—is why Bollinger Bands are a must-learn indicator.
Like everything in the market, it’s not plug-and-play. You’ll need live screen time and backtesting to get a real feel for how bands behave across different tickers.
Want to Get Better With Bollinger Bands Faster?
The fastest improvement comes from testing your rules on different markets and timeframes, then refining what works.
If you want a clean workflow for charting + scanning + testing:
TrendSpider
(exclusive discount code via the link).
Disclosure: This is an affiliate link. If you use it, I may earn a commission at no extra cost to you.
Check out my other articles on indicators that can help you make money.
Also, if you are interested in more trading systems, check out:
Using Ichimoku Clouds for Daytrading
and
The Elder Impulse System.
Bollinger Bands FAQ
What do Bollinger Bands tell you?
They show volatility around a moving average and help identify stretched prices (potential overbought/oversold zones) and volatility compression (squeezes).
Are Bollinger Bands good for day trading?
Yes, but they work best when combined with trend context and risk management. In chop, band touches can whipsaw.
What settings should I use?
The standard is 20 SMA with 2 standard deviations. Some traders adjust to 10/1.5 for short-term or 50/2.5 for long-term. Backtest your market.
Does touching the upper band mean sell?
Not always. In strong trends, price can ride the upper band. Treat it as a “stretch” signal, not an automatic reversal.