RSI Explained: What the 14-Period Number Actually Tells You
Updated 2026-10-23 · 7 min read · By SignalWatch Research
RSI stands for Relative Strength Index. In one sentence: it compares the average size of up moves to the average size of down moves over a lookback window — 14 candles by default — and scales the result to a 0–100 range.
The actual formula
RSI = 100 − (100 ÷ (1 + RS)), where RS is average gain ÷ average loss across the window. If the average gain is 2% and the average loss is 1%, RS = 2 and RSI = 100 − 33.3 = 66.7. Equal gains and losses give RS = 1 and RSI = 50.
| RSI range | What it describes | What it does not mean |
|---|---|---|
| Above 70 | Up moves recently dominated | That price must fall now |
| 50 to 70 | Mild upward momentum | That a trend is confirmed |
| 45 to 55 | Roughly balanced | That nothing is happening |
| 30 to 50 | Mild downward momentum | That a bottom is forming |
| Below 30 | Down moves recently dominated | That you should buy |
Why oversold is not a buy signal
A market can stay below RSI 30 for days or weeks during a downtrend. The indicator is measuring the past, and a strong trend produces a long run of down candles by definition. Buying every RSI 30 in a downtrend is how a strategy with a high win rate in a range quietly destroys an account in a trend.
RSI has no memory of price levels and no concept of value. It cannot tell a healthy pullback from the start of a collapse. Treat it as a description of recent momentum, never as a reason on its own.
Where RSI is genuinely useful
- As a filter inside a defined trend: only look for longs when price is above a rising EMA, then use RSI to time entries rather than to invent trades.
- To spot divergence: price makes a higher high while RSI makes a lower high. Momentum is weakening, which raises the odds of a pause — but divergence often appears several times before price actually turns.
- To avoid chasing: if RSI is already above 75 and you are entering on a breakout, your stop has to be wider, and the position size smaller.
Settings: why 14, and does it matter?
14 comes from Wilder’s original work and roughly balances responsiveness against noise on daily charts. Shorter windows (7–9) react faster and produce more false signals; longer windows (21–28) are smoother and later. Changing the setting does not create an edge — it changes how often you are told something you already know.
The threshold matters too. In strongly trending markets, some traders use 20/80 instead of 30/70 to avoid constant alerts. Pick one pair of thresholds, write it down, and keep it fixed long enough to measure.
FAQ
What does an RSI of 30 mean?+
It means the average down move over the last 14 candles is about twice the average up move (roughly 70/30 weighting). It describes recent momentum, not the probability of a reversal.
Is RSI 70 always a sell signal?+
No. In a strong uptrend RSI can stay above 70 for weeks. Many trend followers treat high RSI as confirmation of strength rather than a reason to sell.
What is RSI divergence?+
Price makes a higher high while RSI makes a lower high (bearish divergence), or price makes a lower low while RSI makes a higher low (bullish divergence). It signals weakening momentum and is a warning, not a trigger.
Which timeframe should I use RSI on?+
Use the timeframe you actually trade, and check one timeframe above it for context. An RSI reading on a 5-minute chart says very little about a position you plan to hold for days.
Related guides
- Risk Management Basics: The Math That Keeps You in the GameFive rules, one formula, and the drawdown table that explains why 1% risk per trade is not arbitrary.
- MACD Crossovers: Golden Cross and Death Cross, Without the HypeThree lines, one lag problem, and a simple filter that removes most of the noise.
- Bollinger Bands: Squeeze, Breakout and the Mean-Reversion TrapTwo bands, two completely different regimes — and the mistake of using one rule for both.
Scan the market, not your screen
Set rules on RSI, MACD, EMA crossovers or Bollinger Bands and get an alert when the condition is validated — on spot and futures.
Get SignalWatch FreeThis article is educational only and does not constitute financial or investment advice. Indicators describe past price behaviour and can be wrong. You are solely responsible for your trading decisions.
← All guides