Read the Relative Strength Index (RSI)

The Relative Strength Index compares the average size of recent gains to the average size of recent losses over a lookback window, usually 14 periods. The result is a number between 0 and 100.

The formula is a ratio, so RSI is a measure of momentum: how strong recent buying was relative to recent selling. It is not a probability of direction and it does not predict what happens next.

Conventionally, readings above 70 are considered overbought and readings below 30 are considered oversold. In strong trends those zones can stay hit for a long time, so alone they are weak signals.

• Above 70 — buying has been unusually aggressive; the move is stretched.
• Below 30 — selling has been unusually aggressive; the move is stretched the other way.
• In a strong uptrend RSI can sit above 70 for weeks; in a strong downtrend it can stay under 30. Context matters more than the number.

A divergence appears when price makes a new high or low but RSI does not. That mismatch means momentum is fading even while price prints an extreme.

Bearish divergence — price makes a higher high while RSI makes a lower high. Bullish divergence — price makes a lower low while RSI makes a higher low. Neither guarantees a reversal; both flag that the move is running out of steam.

Open any symbol, click Indicators, and add RSI to the chart pane. It plots as a line in its own pane with the 30 and 70 guides drawn automatically.

Combine it with trend structure — for example, RSI divergence against a major moving average — rather than trading the oscillator on its own.