Relative Strength Index (RSI)

Introduction

The Relative Strength Index (RSI) is a popular momentum oscillator developed by J. Welles Wilder Jr. in 1978. It measures the speed and change of price movements, fluctuating between 0 and 100. It is primarily used to identify overextended market conditions (overbought/oversold) and potential trendTrendThe general direction in which a security or market is moving over time.Read full glossary entry → reversals.

Why It Matters

• Identifies Extremes: Highlights when buying or selling pressure has become overextended and is ripe for a pause.
• Early Momentum Warning: Divergences between price and RSI show when a trendTrendThe general direction in which a security or market is moving over time.Read full glossary entry → is losing steam before it becomes obvious on the price chart.
• Trend Confirmation: The centerline provides a simple filter to confirm whether buyers or sellers are in control of momentum.

Formula Explanation

RSI is calculated using a two-step formula. First, it determines the Relative Strength (RS), which is the ratio of average gains to average losses over a specific period (typically 14 periods):

Second, the RS value is normalized to fit between 0 and 100:

• 14-Period Default: The standard calculation uses 14 candles (minutes, hours, or days depending on the chart timeframe).

RSI Interpretation

• Overbought (70+): Suggests that the market has risen rapidly, and a temporary pullbackPullbackA temporary price pause or moderate retracement against the primary trend direction.Read full glossary entry → or consolidation is likely. It is a warning to tighten stop-losses on long positions, not an automatic short signal.
• Oversold (30-): Suggests that the market has fallen rapidly, and a technical bounce may be imminent. It is a signal to look for bullish candlestickCandlestickA method of displaying financial price data that shows the open, high, low, and closing prices of a security for a specific time period.Read full glossary entry → patterns.
• The Centerline (50):
  • Above 50 indicates positive momentum (bullish bias).
  • Below 50 indicates negative momentum (bearish bias).

Trading Setup

The Bullish Divergence Reversal Entry

1. Identify the DivergenceDivergenceAn event where the price of an asset moves in the opposite direction of a technical indicator (such as the RSI, MACD, or volume), often signaling a po...Read full glossary entry →: Look for the price to make a new lower low while the RSI registers a higher low (above the 30 level).
2. Wait for Confirmation: Wait for the RSI to rise back above the 30 level, or ideally cross above the 50 centerline.
3. Wait for Price Action: Look for a bullish candlestickCandlestickA method of displaying financial price data that shows the open, high, low, and closing prices of a security for a specific time period.Read full glossary entry → confirmation (e.g., Hammer or Bullish EngulfingBullish EngulfingA two-candle reversal pattern where a small bearish candle is followed by a larger bullish candle whose body completely overlaps or "engulfs" the prev...Read full glossary entry →) on the price chart.
4. Entry: Buy long on the close of the confirmation candle. Place a stop-loss just below the recent swing low. Target the nearest horizontal resistanceResistanceA price level where selling pressure is strong enough to prevent the price from rising further. It represents a "ceiling" on the chart.Read full glossary entry →.

Common Beginner Mistakes

[!WARNING]

• Automatic Trading on Extremes: Buying immediately because RSI is below 30 or selling because it is above 70. In strong trends, RSI can stay overextended for a very long time.
• Ignoring the Major Trend: Trading RSI buy signals during a strong macro downtrendDowntrendA market direction characterized by a sequence of lower highs and lower lows.Read full glossary entry →, or sell signals during a strong macro uptrendUptrendA market direction characterized by a sequence of higher highs and higher lows.Read full glossary entry →.
• Ignoring DivergenceDivergenceAn event where the price of an asset moves in the opposite direction of a technical indicator (such as the RSI, MACD, or volume), often signaling a po...Read full glossary entry → Context: Trading minor divergences in choppy, range-bound markets where they carry little statistical significance.
• Using RSI in Isolation: Relying solely on the RSI oscillator without checking horizontal supportSupportA price level where buying pressure is strong enough to prevent the price from falling further. It represents a "floor" on the chart.Read full glossary entry →/resistanceResistanceA price level where selling pressure is strong enough to prevent the price from rising further. It represents a "ceiling" on the chart.Read full glossary entry → zones, moving averages, or volumeVolumeThe total number of shares, contracts, or units of a security traded during a specified time period.Read full glossary entry →.