i What this calculator does
This calculator works out the upper and lower Bollinger Bands from your moving average, standard deviation, and chosen multiplier, giving you the price levels marking statistically extended moves.
Enter your moving average, standard deviation, and multiplier (typically 2), and the calculator returns the upper and lower bands, closely related to how volatility is actually measured.
This calculator is for educational purposes only. Not financial advice.
How to use the Bollinger Bands Calculator
Every field starts with a sensible default, so a result appears before you change anything at all.
- 1. Moving Average (20-period)
- 2. Standard Deviation
- 3. Multiplier (standard is 2)
The result panel reports:
- Upper Band MA + (
- Lower Band MA - (
- Band Width Upper minus lower
Alongside the headline figures, the calculator reports upper band, lower band, band width, band width %. Those are the numbers that usually explain why the headline result came out where it did.
The breakdown under the result shows the full working, which matters when the answer is surprising.
One caution worth stating. A calculator answers exactly the question you pose to it, and the quality of the answer is set entirely by the inputs. Figures taken from a single period, an optimistic forecast, or a sample too small to be meaningful will produce a precise number that is not a reliable one. Where the result will inform a real decision, run it at several plausible inputs and treat the spread as the answer rather than any single figure.
The same applies to comparisons. A figure is informative against a benchmark, a sector average or the same measure over the company's own history, and much less so on its own. That context is what turns a number into a judgement.
Frequently asked questions
What do the upper and lower bands actually represent?
The bands are set a fixed number of standard deviations above and below a moving average, typically 2 standard deviations, price touching or exceeding a band suggests it's statistically extended relative to its recent volatility, not necessarily a reversal signal on its own.
Why might I want to widen or narrow the standard deviation multiplier?
A wider multiplier (like 2.5 or 3) captures more extreme moves before flagging them, reducing false signals but reacting later, a narrower multiplier (like 1.5) flags moves sooner but produces more frequent, potentially noisier signals.
What does it mean when the bands squeeze together tightly?
A tight squeeze indicates unusually low volatility, often interpreted as a period of consolidation that may precede a significant breakout in either direction, though the direction of that eventual breakout isn't predicted by the squeeze itself.
Does price touching the upper band mean I should sell?
Not automatically, in strong uptrends, price can ride along or repeatedly touch the upper band for extended periods without reversing, many traders combine Bollinger Bands with other indicators rather than trading a band touch in isolation.
How is this different from just using standard deviation alone?
Bollinger Bands specifically translate standard deviation into visual price levels around a moving average, our dedicated Standard Deviation Calculator gives you the raw statistical figure, this calculator applies it directly to price bands for trading context.
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