What the number measures
RSI takes the average gain and average loss over a lookback period — 14 by default — and expresses their relationship on a 0–100 scale. A high reading means recent moves have been overwhelmingly upward; a low reading means the opposite. It measures speed and conviction, not value.
Overbought does not mean sell
This is the single most expensive misunderstanding in technical analysis. In a strong trend RSI can sit above 70 for weeks while price keeps climbing, and shorting each reading above 70 is a reliable way to lose money.
Treat extremes as a description of conditions: strong trends stay extreme. Mean-reversion readings only carry weight in a market that is genuinely ranging.
Divergence: the reading that earns attention
- Bearish divergence: price makes a higher high, RSI makes a lower high — the advance is losing force.
- Bullish divergence: price makes a lower low, RSI makes a higher low — the decline is losing force.
- Divergence signals fading momentum, not an immediate reversal, and can persist far longer than expected.
Bitcoin prints $95,000 with RSI at 78, then $99,000 with RSI at 68. Price is higher, momentum is not — a warning to tighten stops rather than an instruction to short.
Tuning the settings
RSI(14) on a daily chart is the standard. Shortening the period to 7 makes it far more reactive and noisier; lengthening it to 21 smooths it for position trading. In persistent uptrends many traders shift the bands to 40/80 and in downtrends to 20/60 so the tool reflects the regime it is being used in.