Definitions
In plain terms
For symmetric bands it equals twice the multiplier times rolling standard deviation.
Technical
The absolute width is U_t minus L_t and is ready when both bands are ready; it may legitimately equal zero.
Scope
Unlike BandWidth, this raw distance is not divided by the middle band and changes with quote scale.
Formula
Full band width = upper - lower = 2 * k * standard deviationW_t=U_t-L_t=2k\sigma_t| Symbol | Meaning | Unit |
|---|---|---|
U_t | upper band | price units |
L_t | lower band | price units |
k | deviation multiplier | ratio |
sigma_t | rolling standard deviation | price units |
Output unit: price units
Examples
- A reviewer traces Bollinger Full Band Width from aligned inputs through its first-ready row and edge cases before accepting a displayed value.
Common misconceptions
- Unlike BandWidth, this raw distance is not divided by the middle band and changes with quote scale.
Concept relationships
Where this concept is used
Evidence and governance
- Bollinger Bands Rules John Bollinger · first party methodology
Supports: preferred label, short definition, technical definition, formula
Limits: Interpretive rules do not prove forecasting power, trade profitability, or one universal parameter selection.
- TA-Lib Bollinger Bands TA-Lib · first party technical publication
Supports: preferred label, short definition, technical definition, formula
Limits: TA-Lib permits moving-average variants beyond the local close-SMA and population-deviation contract.
- Reviewed by
- fintech-builder-batch-009
- Last reviewed
- 2026-07-30
- Next review
- 2027-07-30
- Record status
- published