RSI Indicator: Complete Guide to the Relative Strength Index

What is the RSI Indicator?

The Relative Strength Index (RSI) is a momentum oscillator that measures the speed and magnitude of recent price changes. It oscillates between 0 and 100 and is one of the most widely used technical indicators.

Developed by J. Welles Wilder Jr. in 1978, RSI helps traders identify overbought and oversold conditions.

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How RSI is Calculated

RSI = 100 - (100 / (1 + RS))

Where RS = Average Gain / Average Loss over the period (typically 14 days)

• RSI above 70: Often considered overbought
• RSI below 30: Often considered oversold
• RSI at 50: Neutral momentum

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RSI Trading Signals

1. Overbought/Oversold

Traditional interpretation:

• RSI > 70: Overbought, consider selling
• RSI < 30: Oversold, consider buying

Warning: In strong trends, RSI can stay overbought/oversold for extended periods!

2. RSI Divergence

Bullish Divergence: Price makes lower low, but RSI makes higher low → Potential reversal up

Bearish Divergence: Price makes higher high, but RSI makes lower high → Potential reversal down

3. RSI Centerline Crossover

• RSI crosses above 50: Bullish momentum building
• RSI crosses below 50: Bearish momentum building

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RSI Trading Strategies

Strategy 1: Mean Reversion

Buy: RSI drops below 30

Sell: RSI rises above 50 (or 70)

Stop: 3-5% below entry

Best for: Ranging markets, stable stocks

Strategy 2: Momentum Confirmation

Buy: RSI crosses above 50 AND price above 20 EMA

Sell: RSI drops below 40

Best for: Trending markets

Strategy 3: Divergence Trading

Buy: Bullish RSI divergence confirmed by candle pattern

Sell: Take profit at resistance or RSI > 60

Best for: Reversal trading, swing trades

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RSI Settings

| Period | Best For |

|--------|----------|

| 7 | Short-term, day trading |

| 14 | Standard, most common |

| 21 | Longer-term, position trading |

Shorter periods = more signals, more noise

Longer periods = fewer signals, more reliable

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Common RSI Mistakes

• Selling just because RSI > 70 - Strong stocks stay overbought
• Ignoring the trend - RSI works differently in trends vs ranges
• Using RSI alone - Combine with price action and other indicators

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Automate RSI Trading

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"Buy SPY when RSI drops below 30 and price is above the 200-day moving average. Sell when RSI rises above 50. Stop loss 3%."

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