Bollinger Bands
How Bollinger Bands Work
Created by John Bollinger in the 1980s, the indicator has three lines on the chart:
Middle Band: A 20-period simple moving average (SMA) — the baseline trend.
Upper Band: The middle band plus 2 standard deviations of price.
Lower Band: The middle band minus 2 standard deviations of price.
Upper Band = 20-period SMA + (2 × standard deviation)
Lower Band = 20-period SMA − (2 × standard deviation)
With standard settings, roughly 95% of price action falls within the two bands. When price touches or exceeds a band, it’s statistically unusual — not necessarily a signal to act, but a flag that conditions are stretched.
Reading Bollinger Bands
| What You See | What It Means |
|---|---|
| Price touching the upper band | Price is relatively high — momentum is strong, but it may be overextended |
| Price touching the lower band | Price is relatively low — could be oversold, but could also be a strong downtrend |
| Bands widening | Volatility is expanding — a big move is underway |
| Bands narrowing (the “squeeze”) | Volatility is contracting — a breakout in either direction may be imminent |
| Price riding the upper band | Strong uptrend — “walking the band” is bullish, not overbought |
| Price riding the lower band | Strong downtrend — sustained weakness, not automatically a buy |
The Bollinger Squeeze
The squeeze is one of the most popular Bollinger Band setups. When the bands contract to unusually narrow widths, it signals that volatility has compressed — and historically, low volatility leads to high volatility. A big move is loading up, but the bands don’t tell you the direction.
Traders watch for the squeeze and then wait for price to break decisively above or below the bands with strong volume. The direction of the breakout sets the trade. A squeeze that resolves upward on heavy volume is a bullish signal; one that resolves downward is bearish.
Combining the squeeze with a momentum indicator like the RSI or MACD can help confirm the breakout direction before committing capital.
Bollinger Band Bounce
In range-bound markets, prices tend to oscillate between the upper and lower bands. The bounce strategy is straightforward: buy near the lower band when the price shows signs of reversing, and sell near the upper band when momentum stalls. This works well during sideways consolidation but fails in trending markets where price “walks the band” for extended periods.
Combining Bollinger Bands with Other Indicators
Bollinger Bands + RSI: Price at the lower band while the RSI dips below 30 provides a higher-conviction oversold signal than either indicator alone.
Bollinger Bands + Volume: A squeeze breakout confirmed by a volume surge is far more reliable than one on thin volume.
Bollinger Bands + MACD: A bullish MACD crossover occurring as price bounces off the lower band aligns trend momentum with a mean-reversion entry.
For detailed strategies and chart examples, see our Bollinger Bands Guide.
Default vs. Custom Settings
| Setting | Parameters | Use Case |
|---|---|---|
| Standard | 20 SMA, 2 standard deviations | All-purpose default; works on daily, weekly, and intraday charts |
| Tighter bands | 20 SMA, 1.5 standard deviations | More sensitive — generates more signals with more false positives |
| Wider bands | 20 SMA, 2.5 standard deviations | Fewer signals but price reaching the bands is more significant |
| Short-term | 10 SMA, 1.5 standard deviations | Day trading and scalping on intraday charts |
Key Takeaways
- Bollinger Bands place volatility-based envelopes around a 20-period moving average.
- The bands widen with rising volatility and contract when volatility falls.
- The squeeze — extremely narrow bands — signals that a big move is coming, though not the direction.
- Touching a band isn’t a trade signal on its own; context (trending vs. range-bound) matters.
- Combine with RSI, MACD, or volume for confirmation and higher-probability setups.
Frequently Asked Questions
What does a Bollinger Band squeeze indicate?
A squeeze means volatility has compressed to a low level — the bands are unusually narrow. This typically precedes a sharp move in one direction. Traders watch for the breakout above or below the bands, confirmed by volume, to determine the direction.
Are Bollinger Bands a leading or lagging indicator?
They’re primarily reactive — the bands are calculated from past price data, making them lagging. However, the squeeze setup has a forward-looking quality because it identifies conditions where a breakout is statistically likely, even though it doesn’t predict direction.
Do Bollinger Bands work for long-term investing?
Yes, though they’re more popular with shorter-term traders. Long-term investors can apply Bollinger Bands on weekly or monthly charts to identify periods of extreme volatility or to time entries during pullbacks within a broader uptrend. The principles are identical — only the time frame changes.