Relative Strength Index (RSI)
Returns the Relative Strength Index, a momentum oscillator that measures the speed and magnitude of recent price changes to evaluate overbought or oversold conditions.
How RSI Works
RSI oscillates between 0 and 100:
- RSI > 70: Generally considered overbought (potential sell signal)
- RSI < 30: Generally considered oversold (potential buy signal)
- RSI = 50: Neutral momentum
Parameters
| Parameter | Description | Default |
|---|---|---|
| Symbol | Stock ticker symbol | Required |
| Days | Number of periods for calculation | 14 |
| StartDate | Calculate RSI as of this date | Today |
Calculation
RSI = 100 - (100 / (1 + RS))
Where RS = Average Gain / Average Loss over the period.
Examples
=RelativeStrengthIndex("AAPL")=RelativeStrengthIndex("AAPL", "14")=RelativeStrengthIndex("MSFT", "21")=RelativeStrengthIndex("SPY", "9")=RelativeStrengthIndex("AAPL", "14", DATE(2024,1,15))Symbol from cell reference
When to Use
- Identify overbought and oversold conditions
- Confirm trend strength and potential reversals
- Generate buy/sell signals based on RSI thresholds
- Compare momentum across multiple stocks
- Technical analysis and trading strategies
When NOT to Use
Common Issues & FAQ
Q: Why is RSI returning "NA"? A: Check that:
- The symbol is valid and actively traded
- There is sufficient historical data for the period
- The date format is correct (YYYY-MM-DD)
Q: What period should I use? A: The default 14-day period is most common. Shorter periods (7-9) are more sensitive, longer periods (21-25) are smoother.
Q: How do I interpret RSI divergence? A: When price makes new highs but RSI doesn't (bearish divergence) or price makes new lows but RSI doesn't (bullish divergence), it may signal a reversal.
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