Bollinger Bands on TradingView — Pine Script v5 Source

Pine Script has ta.bb built in, so plotting the bands from the explainer is a couple of lines. We’ll add the filled channel, a squeeze highlighter, and the %b reading.

What you’ll need

• A TradingView account (free tier is fine)
• The Pine Editor

The source

//@version=5
indicator("AlgoGen Bollinger Bands", shorttitle="AG BB", overlay=true)

length = input.int(20, "Length", minval=1)
mult   = input.float(2.0, "StdDev", minval=0.1, step=0.1)

[mid, upper, lower] = ta.bb(close, length, mult)

p_up  = plot(upper, "Upper", color=#4a3aa7)
p_lo  = plot(lower, "Lower", color=#4a3aa7)
plot(mid, "Middle", color=#eb6834, linewidth=2)
fill(p_up, p_lo, color=color.new(#2a78d6, 92), title="Band fill")

// Squeeze: bandwidth at a 100-bar low.
bandwidth = (upper - lower) / mid
squeeze   = bandwidth <= ta.lowest(bandwidth, 100)
bgcolor(squeeze ? color.new(color.gray, 85) : na, title="Squeeze")

ta.bb returns [middle, upper, lower], and — importantly — it uses the population standard deviation, matching every other version in this series. The fill shades the channel; the bgcolor line flags a squeeze whenever bandwidth hits a 100-bar low.

%b as a separate pane

//@version=5
indicator("AlgoGen %b")
[mid, upper, lower] = ta.bb(close, 20, 2.0)
pctB = (close - lower) / (upper - lower)
plot(pctB, "%b", color=#2a78d6, linewidth=2)
hline(1, "Upper"), hline(0, "Lower"), hline(0.5, "Mid", color=color.gray)

Squeeze breakout alerts

Because the squeeze is the most respected Bollinger signal, here’s how to alert on a breakout out of a squeeze — the volatility contraction followed by price escaping the band:

firedUp   = squeeze[1] and close > upper
firedDown = squeeze[1] and close < lower
alertcondition(firedUp,   "BB squeeze break up",   "Price broke above upper band out of a squeeze")
alertcondition(firedDown, "BB squeeze break down", "Price broke below lower band out of a squeeze")

Note the squeeze[1] — we check that the previous bar was in a squeeze and this bar broke out, so the signal fires on the expansion, not during the quiet period.

Adding it

1. Paste and Add to chart (overlay=true draws on price).
2. Tune length and multiplier together, as the explainer recommends.
3. Right-click → Add alert, and pick one of the alert conditions above.

Gotchas

• Population std, handled for you. ta.bb (and ta.stdev) use population standard deviation, so you don’t hit the ddof trap here — but know it’s why Pine matches Python’s ddof=0 and not its default.
• Tuple order. ta.bb returns [middle, upper, lower] — middle first.
• Squeeze is relative. ta.lowest(bandwidth, 100) defines “narrow” over the last 100 bars; change the window to change the sensitivity.

Same indicator elsewhere: Python, MQL5, EasyLanguage, NinjaScript. Then test a squeeze breakout in AlgoGen.

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This post is educational, not financial advice. Indicators describe the past; they don’t predict the future. Backtest anything before you risk real money on it.