RSI on TradingView — Pine Script v5 Source

TradingView is where most people first meet the RSI, and Pine Script makes it almost embarrassingly easy to build your own. We’ll do it twice: the one-line built-in, and a from-scratch version so you can see there’s no magic — and so you can modify the smoothing if you ever want to.

What you’ll need

• A TradingView account (the free tier is fine)
• Open Pine Editor at the bottom of any chart

The built-in version

//@version=5
indicator("AlgoGen RSI", shorttitle="AG RSI", overlay=false, precision=2)

length = input.int(14, "RSI Length", minval=1)
src    = input.source(close, "Source")

rsiValue = ta.rsi(src, length)

plot(rsiValue, "RSI", color=color.new(#2a78d6, 0), linewidth=2)
hline(70, "Overbought", color=color.new(color.gray, 0))
hline(30, "Oversold",   color=color.new(color.gray, 0))
fill(hline(70), hline(100), color=color.new(#e34948, 90))
fill(hline(0),  hline(30),  color=color.new(#1baf7a, 90))

ta.rsi already uses Wilder’s smoothing internally, so this matches every other implementation in the series out of the box. The two fill calls shade the overbought and oversold zones, giving you the same look as the output chart above.

The from-scratch version

Want to prove it to yourself, or swap in different smoothing? Here’s the RSI without ta.rsi, using ta.rma — which is Wilder’s rolling average:

//@version=5
indicator("AlgoGen RSI (manual)", shorttitle="AG RSI m", precision=2)

length = input.int(14, "RSI Length", minval=1)

change = ta.change(close)
gain   = math.max(change, 0.0)
loss   = math.max(-change, 0.0)

avgGain = ta.rma(gain, length)   // rma == Wilder's smoothing
avgLoss = ta.rma(loss, length)

rsiValue = avgLoss == 0 ? 100 : 100 - (100 / (1 + avgGain / avgLoss))

plot(rsiValue, "RSI", color=#2a78d6, linewidth=2)
hline(70), hline(30)

Both plots sit exactly on top of each other. That’s the point: ta.rsi is just this, wrapped up.

Adding it to your chart

1. Paste either script into the Pine Editor.
2. Click Add to chart.
3. Adjust the length in the settings gear. Done.

Gotchas

• ta.rma vs ta.sma. If you build it from scratch with ta.sma, you’ll get a simple-average RSI that won’t match TradingView’s built-in. Use ta.rma. This is the Pine version of the same “wrong smoothing” bug we warn about everywhere.
• Repainting. On the last, still-forming bar, RSI updates tick by tick until the bar closes — that’s expected, not a bug. For alerts, gate on barstate.isconfirmed if you only want closed-bar signals.
• Colors. Pine’s color.new(hex, transparency) takes transparency 0–100, where 90 is very faint — that’s what gives the soft zone fills.

Same RSI elsewhere: Python, MQL5, EasyLanguage, NinjaScript. And the only opinion that counts is the equity curve — test an RSI strategy 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.