how to calculate BollingerBandWidth ?

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11/28/2022 at 5:18 PM #204961 quote
ZeroCafeine
Participant

Senior
Hi everyone,

someone can tell me how this variable “BollingerBandWidth” is calculated please, because I don’t find the same result with a manual calculation, maybe it’s not the same standard deviations or something is missing, I get A different of D ?
```
A = BollingerBandWidth[20](Close)

BBUp = BollingerUp[20]
BBDown = BollingerDown[20]

D = BBUp - BBDown

Return A, D
```
Best Reguards
11/28/2022 at 5:25 PM #204964 quote
robertogozzi
Moderator

Legend
There you go:
```
//
// Bollinger BB%
//
DEFPARAM CalculateOnLastBars = 1000
p       = 20
dev     = 2.0
BollInf = Average[p,0](close) - (dev * std[p](close))
BollSup = Average[p,0](close) + (dev * std[p](close))
pB      = ((close - BollInf) / (BollSup - BollInf)) * 100
return pB AS "Boll BB %",80 AS "Ob",20 AS "Os"
```
11/29/2022 at 9:13 AM #204988 quote
Nicolas
Keymaster

Legend
Bollinger B% is not the same as Bollinger BandWidth, as per our documentation: https://www.prorealcode.com/documentation/bollingerbandwidth/

Calculation :

Indicator = ((Boll+) – (Boll-)) / moving average
```
a = BollingerBandWidth[20](close)
b = (BollingerUp[20](close)-BollingerDown[20](close))/average[20]

return a , b
```
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11/29/2022 at 11:42 AM #205009 quote

robertogozzi
Moderator

Legend

I misunderstood the text. Sorry.

ZeroCafeine thanked this post

12/05/2022 at 1:21 PM #205276 quote

ZeroCafeine
Participant

Senior

tks you all,

so when I red the fonction’s name of : “BollingerBandWidth” I understood it’s the difference betwen the 2 bollinger band like : BB Up – BB Down, but this is not the case,

tks again,
Best Reguards
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