Plain-English definitions, reviewed by an independent investor

RSI (Relative Strength Index)

RSI gauges recent momentum on a 0–100 scale to flag when a stock may be overbought or oversold.

RSI gauges recent momentum on a 0–100 scale to flag when a stock may be overbought or oversold.

RSI = 100 − 100 ÷ (1 + Average Gain ÷ Average Loss)

Why it matters

It helps spot extremes where a reversal may be due.

Common confusion

Strong trends can stay overbought for a long time; RSI alone is not a trigger.

Definitions reviewed by the Investing Glossary editorial team.

Frequently Asked Questions

What RSI is oversold?

Below 30 is the common oversold line; above 70 oversold’s opposite, overbought.

Use RSI alone?

Better with trend and volume; it confirms, it does not decide.

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