Skip to main content

​
Relative Strength Index (RSI)

The Relative Strength Index is a momentum oscillator that measures the speed and magnitude of recent price changes on a scale of 0 to 100. Developed by J. Welles Wilder, RSI identifies overbought and oversold conditions and is one of the most widely used indicators in technical analysis.

​
How It Works

RSI is calculated in two steps: Step 1 — Relative Strength:
Step 2 — Normalize to 0–100:
The “average gain” and “average loss” use a smoothed (Wilder’s) moving average: the first value is a simple average, and subsequent values use:
This smoothing means the RSI is influenced by all prior data, not just the most recent N bars — though the influence of older bars decays exponentially.

​
Indicator Type

Subchart — RSI is rendered in a separate panel below the main price chart with its own 0–100 Y-axis.

​
Settings

​
Display Settings

​
Period Tuning

The standard 14-period RSI works well in most situations. Shortening the period makes RSI reach overbought/oversold more frequently (more signals, more noise). Lengthening it makes RSI smoother but slower to react.

​
Interpretation

​
Overbought and Oversold

The classic interpretation:
  • RSI above 70: Overbought — the asset has been rising aggressively and may be due for a pullback.
  • RSI below 30: Oversold — the asset has been falling aggressively and may be due for a bounce.
However, these are not automatic reversal signals. In strong trends, RSI routinely stays in overbought or oversold territory for extended periods. In a strong uptrend, RSI rarely drops below 30. The effective range shifts upward: Some traders adjust the overbought and oversold settings to match the prevailing trend. For example, in a confirmed bull market on the daily chart, setting overbought to 80 and oversold to 40 produces more useful signals.

​
Centerline Crossovers

  • RSI crossing above 50: Momentum shifting bullish. Average gains exceeding average losses.
  • RSI crossing below 50: Momentum shifting bearish. Average losses exceeding average gains.
The 50 level acts as a trend filter: sustained RSI above 50 = bullish regime, sustained below 50 = bearish regime.

​
Failure Swings

A failure swing is a specific RSI pattern that Wilder himself considered the strongest RSI signal: Bullish failure swing:
  1. RSI drops below 30 (oversold).
  2. RSI bounces above 30.
  3. RSI pulls back but stays above 30 (does not make a new low).
  4. RSI breaks above the bounce high → buy signal.
Bearish failure swing:
  1. RSI rises above 70 (overbought).
  2. RSI drops below 70.
  3. RSI rallies but stays below 70 (does not make a new high).
  4. RSI breaks below the pullback low → sell signal.

​
RSI Trend Lines

You can draw trend lines on the RSI subchart itself:
  • A broken RSI uptrend line often precedes a price breakdown.
  • A broken RSI downtrend line often precedes a price breakout.
  • RSI trend line breaks typically lead price trend line breaks by 1–3 bars.

​
Alerts

RSI supports the following alert rules:
In strong trends, RSI can stay overbought or oversold for extended periods — an overbought reading alone is not a sell signal. Look for RSI divergences, failure swings, or combine with price action at key levels for higher-probability setups.

​
Combining with Other Indicators

​
Common Pitfalls

  1. Mechanical overbought = sell, oversold = buy — This works in ranges but fails badly in trends. Always determine market context first.
  2. Ignoring the 50 line — The centerline is more useful as a trend filter than the 70/30 levels in many situations.
  3. Too-short period on high timeframes — RSI(7) on a daily chart produces many false signals. Use 14 or higher for daily+ charts.
  4. Not confirming with price action — RSI should confirm what price structure suggests, not override it. An oversold RSI does not help if price structure is clearly bearish (lower lows, lower highs, breaking support).

​
Practical Considerations

  • Startup period: RSI requires approximately 10 × period bars to fully stabilize due to Wilder’s smoothing method. The first few RSI values on a freshly loaded chart may differ slightly from stabilized values.
  • All timeframes: RSI works on any timeframe from 1-minute to monthly. Lower timeframes produce more noise; higher timeframes produce smoother, more reliable signals.
  • Crypto-specific: Crypto markets trend harder than equities. In a crypto bull run, RSI(14) on the daily chart can stay above 70 for weeks. Consider the adjusted levels table above.
  • RSI Divergence — Automatically detects price-RSI divergences
  • MACD — Complementary momentum indicator based on moving average convergence
  • Bollinger Bands — Volatility bands for overbought/oversold confluence