# What Are Bollinger Bands and How Are They Read?

> Bollinger Bands default to a 20-period simple moving average with bands two standard deviations above and below, which widen when volatility rises and narrow when it falls [1].

Last updated: 2026-10-22 · https://www.nx24.ai/en/rehber/bollinger-bantlari

## What are Bollinger Bands?

A volatility indicator made of a 20-period moving average in the middle and two bands placed two standard deviations above and below it.

## What does band width say?

When the bands narrow, volatility is low and a sharp move may follow the squeeze. When they widen, volatility has increased.

## Touching the upper or lower band

A touch of the upper band is not a sell signal by itself; in strong trends price can walk along the band. In sideways markets a return to the average is more common.

## Combine with other indicators

RSI divergence, volume and support/resistance levels reduce false signals.

## Source note

John Bollinger developed Bollinger Bands; the default is a 20-period simple moving average with bands two standard deviations above and below, which widen when volatility rises and narrow when it falls [1].

## Limits

The bands show volatility, not direction. This page is educational, not investment advice.

## Frequently asked questions

**What are the default Bollinger Band settings?**

In the bands developed by John Bollinger, the default is a 20-period simple moving average with bands two standard deviations above and below [1].

**What happens when the bands widen?**

The bands widen when volatility rises and narrow when it falls [1].

## Sources

1. [Bollinger Bands](https://chartschool.stockcharts.com/table-of-contents/technical-indicators-and-overlays/technical-overlays/bollinger-bands). StockCharts ChartSchool. Accessed: 2026-10-22.

---
Not investment advice. NX24 — https://www.nx24.ai/