RSI Indicator: How to Use the Relative Strength Index

The RSI indicator (relative strength index) is a momentum oscillator that measures the speed and size of recent price moves on a scale from 0 to 100. Readings above 70 are called overbought and below 30 oversold, but the RSI indicator is most useful for reading trend strength, spotting divergence and timing pullbacks. It is one of the core tools covered in our guide to technical indicators.

Quick answer: The RSI indicator (relative strength index) is a momentum oscillator created by J. Welles Wilder in 1978 that compares average gains with average losses over 14 periods and plots the result from 0 to 100. RSI is neither bullish nor bearish by itself: an RSI signal such as divergence is only confirmed when price breaks structure in the same direction.

---

What is the RSI indicator?

The RSI indicator is a momentum oscillator that tells you how strongly price has been moving up compared with how strongly it has been moving down over a set lookback window. J. Welles Wilder introduced the relative strength index in his 1978 book New Concepts in Technical Trading Systems, the same book that introduced the Average True Range. The relative strength index is not the stock-picking "relative strength" that compares a stock with an index; RSI compares one market only with its own recent history.

RSI key facts

How is RSI calculated?

The RSI calculation compares the average size of up-closes with the average size of down-closes over 14 periods, then converts that ratio into a number between 0 and 100. In plain terms:

1. For each of the last 14 candles, record the gain if the close was higher than the previous close, or the loss if it was lower.
2. Average the gains and average the losses. Wilder used his own smoothing method (a type of exponential average) so that each new candle adjusts the averages gradually rather than dropping an old value abruptly.
3. Divide the average gain by the average loss. The result is called relative strength (RS).
4. Convert RS into the index: RSI = 100 minus 100 divided by (1 + RS).

All up-closes give 100, all down-closes give 0, and equal gains and losses give 50.

What do overbought and oversold mean on the RSI?

On the RSI indicator, overbought means RSI is above 70 and oversold means RSI is below 30. Overbought tells you that recent gains have been large compared with recent losses. Overbought does not mean a reversal is due.

The chart below shows price with a 14-period RSI panel underneath. The first marker is an overbought reading above 70 after the rally, and the second is an oversold reading below 30 during the decline that followed.

In this example both readings came close to turns in price, which is the textbook picture. The caption makes the more important point: in a strong trend, RSI can stay above 70 or below 30 for a long time while price keeps going.

Why are overbought and oversold not sell and buy signals?

Overbought and oversold readings are not sell and buy signals because RSI measures momentum, and strong momentum usually comes from a real trend. Overbought and oversold readings work best in a sideways range and should be treated as context in a trend.

How does RSI behave in a trend?

In a trend, the RSI indicator shifts its working range:

• In an uptrend, RSI tends to oscillate between roughly 40 and 80. Pullbacks often stop near 40 to 50 rather than reaching 30.
• In a downtrend, RSI tends to oscillate between roughly 20 and 60. Bounces often stall near 50 to 60 rather than reaching 70.

These range shifts turn the RSI indicator into a trend filter: if RSI keeps holding 40 and reaching 70 to 80, the useful trade is buying pullbacks, not shorting overbought readings.

What does the 50 line on the RSI mean?

The 50 line on the RSI marks the point where average gains equal average losses. RSI holding above 50 means up-moves have been stronger than down-moves over the lookback, and RSI holding below 50 means the reverse. Many traders use the 50 line as a bias filter: longs only above 50, shorts only below 50. A moving average slope tells a similar story, which is why the two pair well.

What is RSI divergence?

RSI divergence happens when price and the RSI indicator disagree. Price makes a new extreme, but RSI does not, which suggests the move is running out of momentum. There are two main types:

• Bearish divergence: price makes a higher high while RSI makes a lower high. Upside momentum is fading.
• Bullish divergence: price makes a lower low while RSI makes a higher low. Downside momentum is fading.

The chart below shows bearish divergence. Price pushes to a higher high, but the RSI peak under that second high is lower than the first, then price turns down.

Price kept rising for many candles after the first RSI high. RSI divergence is a warning, not a trigger: divergence can persist through several higher highs in a strong trend.

How do you confirm RSI divergence?

You confirm RSI divergence by waiting for price structure to break in the direction of the divergence. Follow these steps:

1. Identify two clear swing highs (for bearish divergence) or swing lows (for bullish divergence) on price.
2. Check that RSI shows the opposite: a lower high under the higher price high, or a higher low under the lower price low.
3. Mark the most recent swing low between the two highs (or the swing high between the two lows). That level is your confirmation line.
4. Wait for a candle to close beyond that line. This is a break of structure, and it shows price has actually started to turn.
5. Enter on the close or on a retest of the broken level with a limit order, place the stop beyond the divergence extreme, and size the position so the stop distance fits your risk.

In the chart above, the decline after the lower RSI high carries price below the swing low that formed between the two peaks. Before that break, the divergence was only a warning.

What is hidden divergence?

Hidden divergence is a continuation signal. Hidden bullish divergence occurs when price makes a higher low but RSI makes a lower low, usually during a pullback in an uptrend; hidden bearish divergence is the mirror image in a downtrend.

What is an RSI failure swing?

An RSI failure swing is a reversal pattern Wilder described that uses only the RSI line, not price. A bearish failure swing works like this:

1. RSI rises above 70.
2. RSI pulls back, setting a low (the failure point).
3. RSI rallies again but fails to get back above 70.
4. RSI then breaks below the failure point. That break is the signal.

A bullish failure swing is the reverse below 30. Failure swings work better when price structure agrees.

What are the best RSI settings?

The best RSI settings for most traders are the default 14 periods with levels at 70 and 30, because that is what Wilder chose and what most traders watch. Adjustments by timeframe:

A shorter period hits extremes more often; a longer period is smoother and rarely reaches 70 or 30. Test any setting on your market first.

How do you combine RSI with support and resistance?

The RSI indicator works best combined with price levels, because RSI shows momentum and levels show where a reaction is likely:

• Oversold at support: in a range, an RSI reading near 30 as price tests well-defined support is a far better long setup than an oversold reading in open space.
• Divergence at resistance: bearish divergence into a prior resistance zone gives two independent reasons to expect a stall.
• Trend pullback to a level: in an uptrend, RSI dropping to 40 to 50 while price retests old resistance as support lines up the range shift with structure.
• Momentum cross-check: RSI and the MACD indicator both measure momentum. Agreement between a MACD crossover and an RSI 50-line cross strengthens the read, though the two are related.

A quick sweep below support that reverses is often a liquidity sweep, and an RSI higher low during that sweep is a classic bullish divergence.

What are the most common RSI mistakes?

The most common RSI mistake is treating 70 and 30 as automatic sell and buy levels. Others:

1. Fading strong trends. Shorting overbought readings in an uptrend fights momentum. Check the range shift first.
2. Trading divergence without confirmation. Divergence can last for many candles. Wait for the break of structure.
3. Over-tuning the settings. Tweaking the period until past signals look perfect is curve fitting.
4. Ignoring the higher timeframe. An oversold 5-minute RSI inside a daily downtrend is a weak long.
5. Using RSI alone. RSI knows nothing about levels, volume or news.
6. Overtrading every signal. On lower timeframes RSI produces constant readings. More signals is not more edge, and as Gianluca Pizzituti, CEO of Velotrade, puts it: "A profitable trade and a good trade are two completely different things."

Can AI improve RSI signals?

AI tools can improve RSI signals mainly by scanning many markets at once and flagging divergence or failure swings faster than a person can. Pattern-recognition models and AI trading signals are useful for building a shortlist to review.

The limits are the same as for manual analysis. Which swing highs count for a divergence is partly subjective, so different tools flag different signals, and scanners produce many false positives in trending markets. Any AI-flagged RSI setup needs backtesting and human judgement about context, structure and risk before it becomes a trade.

How do you use RSI in a prop trading challenge?

In a prop challenge the RSI indicator is a timing tool, and risk rules decide whether the trade is worth taking. At Velotrade, a multi-asset prop trading firm offering simulated evaluations across crypto, forex, stocks, index ETFs and commodities, two limits matter most:

• Daily loss limit: the daily loss limit resets at 00:30 UTC and is set from the higher of your balance or your equity at that time.
• Static maximum drawdown: the maximum drawdown is a fixed dollar floor that does not trail your profits. Read how static maximum drawdown works before sizing up.

A sensible process: use RSI for context (range shift, 50 line), use divergence plus a break of structure for the trigger, place the stop beyond the swing that formed the divergence, then size the trade with the position size calculator so a stop-out costs a small fraction of the daily limit. Check that the target offers enough reward for the risk; the risk-reward ratio guide explains the maths. When you are ready, compare the challenges.

This article is educational and is not investment advice. Velotrade challenges are simulated evaluations.