Quick Answer: What Are Bollinger Bands and How Do You Use Them?
Bollinger Bands, created by John Bollinger, are a volatility indicator drawn as three lines around price that widen when the market gets volatile and tighten when it goes quiet. These terms cover most of what a beginner needs to know:
- Three bands
- A 20-period simple moving average as the middle band, with an upper and a lower band set 2 standard deviations above and below it.
- BandWidth
- (Upper − Lower) ÷ Middle; it shows how wide the bands are relative to price, so it is the clean way to spot a squeeze or an expansion.
- %b
- Shows where price sits relative to the bands, making it easier to judge how close price is to the upper or lower band.
- Squeeze
- A quiet phase where BandWidth falls to a low relative to its recent past and the bands pinch together, often before a more active move.
- Breakout
- The first move outside the bands after a squeeze; the question is whether it is real expansion or a false poke.
- Band ride
- In a strong trend, price closing at or near the upper (or lower) band for many candles is a sign of strength, not exhaustion.
- W-bottom / M-top
- Classic reversal shapes that use the band as a reference, most useful when the market is ranging.
What you will learn
- What Bollinger Bands are and how they are calculated
- How BandWidth and %b turn the bands into numbers
- How to spot a squeeze and judge a real breakout
- Why a band ride is strength, not exhaustion
- How W-bottoms and M-tops work, and how to combine signals
What Are Bollinger Bands?
Bollinger Bands, created by John Bollinger, are a volatility indicator drawn as three lines around price. Unlike a fixed-percentage envelope, the bands widen when the market gets volatile and tighten when it goes quiet, so they adapt to whatever price is doing.
- The Middle Band — a 20-period simple moving average of price, the "average" everything else is measured from.
- The Upper Band — the middle band plus 2 standard deviations, marking where price is high relative to its recent range.
- The Lower Band — the middle band minus 2 standard deviations, marking where price is low relative to its recent range.
Visualising It: The Three Bands
Price (dark) moves inside a channel built around the 20-period average (gold). Most candles close between the outer bands.
A touch of a band is not a buy or sell signal. It only says price is high or low relative to its recent average. What price does next, and what the bands are doing, gives the actual read.
How Bollinger Bands Are Calculated
The default and most widely used setting is 20 periods and 2 standard deviations:
- Middle Band = 20-period simple moving average (SMA) of the closing price.
- Upper Band = Middle Band + (2 × standard deviation of the last 20 closes).
- Lower Band = Middle Band − (2 × standard deviation of the last 20 closes).
Standard deviation measures how far prices are scattered around their average. Scattered prices give a large number and wide bands, and tightly packed prices give a small number and narrow bands. Your charting platform plots all of this automatically, but knowing the mechanics explains why the bands behave as they do.
If you shorten or lengthen the period, Bollinger's own rule of thumb is to nudge the deviation too, for example about 1.5 for a 10-period band and about 2.1 for a 50-period band. Most traders simply keep 20 and 2. Note that the "roughly 95% of prices fall inside the bands" idea is an approximation: markets are not perfectly bell-shaped, and price can stay outside the bands for a while.
The middle band is a simple average, so it is worth knowing how it compares with an exponential one. See our EMA vs SMA guide.
BandWidth and %b: Turning the Bands Into Numbers
Two simple readings built from the bands make them easier to judge objectively:
- BandWidth = (Upper − Lower) ÷ Middle. It shows how wide the bands are relative to price, so it is the clean way to spot a squeeze or an expansion. Compare it against its own recent history on the same chart, not against a fixed number.
- %b = (Close − Lower) ÷ (Upper − Lower). It shows where price sits inside the bands.
| %b reading | Where price is |
|---|---|
| Above 1.0 | Closing above the upper band |
| 1.0 | Exactly on the upper band |
| 0.5 | On the middle band |
| 0.0 | Exactly on the lower band |
| Below 0.0 | Closing below the lower band |
Together, BandWidth answers "how volatile is the market right now?" and %b answers "where is price within that range?".
The Squeeze: Volatility Contraction Before the Move
Volatility moves in cycles: quiet periods tend to be followed by active ones, and active ones by quiet ones. A squeeze is the quiet phase, when BandWidth falls to a low relative to its recent past and the bands pinch together around price.
Visualising It: Squeeze, Then Expansion
The bands narrow while price coils sideways. When volatility returns, the bands open up as price breaks out.
A squeeze says a bigger move is more likely. It says nothing about direction or exact timing, and some squeezes simply get tighter for longer. Treat it as a "get ready" alert, not an entry.
A practical approach is to mark the high and low of the squeeze range and wait for a decisive close beyond it. On intraday Nifty and Bank Nifty charts, squeezes often form during quiet mid-session consolidation, but shorter timeframes also produce more false starts, so a higher-timeframe trend read matters even more there.
Breakouts: Real Expansion vs a False Poke
After a squeeze, the question is whether the first move outside the bands is real. Traders look for evidence on three fronts:
Candle Closes Outside the Band
A candle that only wicks outside and closes back inside is a warning, not a confirmation.
BandWidth Starts Expanding
The bands opening up shows volatility is genuinely returning, not just a single spike.
Volume Supports the Move
Participation behind the break makes it more credible. See our volume analysis guide.
Bollinger himself has noted that the first break out of a squeeze is often a false one, a "head fake", with the true move going the other way. This is why waiting for a close and confirmation beats chasing the very first poke outside the band.
Band Rides: When "Overbought" Keeps Going
In a strong trend, price can close at or near the upper band for many candles in a row. This is a band ride, and it is a sign of strength, not exhaustion. The same applies in reverse along the lower band in a downtrend.
Visualising It: Riding the Upper Band
Price hugs the upper band while the middle band slopes up. A pullback that holds near the middle band is a continuation clue.
- The middle band acts as a dynamic support in an uptrend (and resistance in a downtrend).
- A first warning is often a close back through the middle band with the bands flattening or turning.
- Selling simply because price touched the upper band, without any sign of weakness, is fighting the trend.
W-Bottoms and M-Tops: Reversals Inside the Bands
The bands can also help frame reversals, particularly when the market is ranging. Two classic shapes use the band as a reference:
Visualising It: W-Bottom and M-Top
A W-bottom's second low holds above the lower band after the first low pushed outside it. An M-top mirrors this at the upper band.
The idea is that the second push shows weaker momentum, since price could not tag the band again. Like divergence on RSI or MACD, this is a caution flag to confirm, not a standalone trigger.
| Behaviour | What the bands look like | What it suggests | Common trap |
|---|---|---|---|
| Squeeze | Narrow, flat, close together | Volatility low, bigger move likely | Guessing direction early |
| Breakout | Bands opening after a squeeze | Volatility returning | Trading a wick, not a close |
| Band ride | Sloping bands, price on one edge | Strong trend in force | Shorting "overbought" |
| Range / reversal | Flat bands, price bouncing | Mean reversion more likely | Fading a trend that is starting |
Combining Bollinger Bands With Other Tools
Bollinger Bands describe volatility and relative price, so they answer different questions from momentum indicators. Pair them with tools that answer the rest: RSI or MACD for momentum, volume for participation, and support and resistance for structure. A squeeze breakout that also clears a known resistance zone on strong volume carries far more weight than a lone band poke in the middle of nowhere.
This guide is for education and is not investment advice. No indicator predicts the future, so always trade with a predefined stop-loss and sensible position sizing.
Common Bollinger Bands Mistakes
Selling every upper-band touch
Treating a touch as automatic "overbought" and shorting into a band ride.
Assuming a squeeze has a direction
Picking a side before price closes outside the range and gets caught by the head fake.
Trading wicks, not closes
Entering on a candle that pokes outside the band but closes back inside.
Ignoring the trend behind the bands
Using mean-reversion logic when the middle band is sloping hard in one direction.
Tweaking settings to fit past charts
Over-optimising the period and deviation until it looks perfect in hindsight but fails live.
No stop-loss on band trades
Entering without a defined invalidation point, so one failed breakout becomes an open-ended loss.
Your Bollinger Bands Reading Checklist
Before acting on any Bollinger Band setup, run through this five-point check:
Trend or Range?
Is the middle band sloping clearly, or flat with price bouncing? This decides whether you think "ride" or "reversion".
What Is BandWidth Doing?
Contracting into a squeeze, expanding into a move, or already wide and stretched?
Close, Not Just a Wick
Did a candle actually close outside the band, or only poke through it?
Volume and Structure Agree
Does volume support the move, and is there a nearby support or resistance level that agrees?
Defined Risk
Do you know exactly where the idea is proven wrong, and have you placed a stop-loss there?
Learn the Stock Market with Deepak Kevadia: Boisar, Dahanu, Palghar & Online
This guide is part of the free learning library from Chart Code, founded and mentored by Deepak Kevadia (BSE NISM Certified). Spotting a squeeze is step one; judging whether the breakout is real on live charts with a mentor is step two. Chart Code's trading course is taught in person at Boisar and live online, so students from Boisar, Dahanu and Palghar, and anywhere in India, can join.
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