RSI indicator explained: overbought, oversold and divergence

The Relative Strength Index, almost always called RSI, is one of the first indicators new traders add to a chart, and one of the most misread. Many beginners learn a single rule, sell above 70 and buy below 30, and then watch a strong trend run straight through it. Used properly, RSI is not a buy or sell button. It is a way to measure the strength of recent moves, spot when momentum is fading, and judge whether a trend is healthy. This guide explains how RSI is calculated, what the levels really mean, how divergence works, and how to use RSI sensibly on currency pairs and gold.

What the RSI indicator measures

RSI is a momentum oscillator. It compares the size of recent gains with the size of recent losses and turns the result into a number between 0 and 100. A high reading means that, over the chosen period, up closes have been larger than down closes. A low reading means the opposite. It was introduced by J. Welles Wilder Jr. in his 1978 book New Concepts in Technical Trading Systems, the same book that introduced the Average True Range.

Three points are worth fixing in your mind before using it:

• RSI measures speed, not value. A reading of 75 says price has risen quickly. It does not say the pair is expensive or that it must fall.
• RSI is bounded. Unlike price, it can never go above 100 or below 0, which makes readings easy to compare across pairs, gold and timeframes.
• RSI is built from closes. Wicks do not count, so a candle with a long spike but a quiet close barely moves the indicator.

How RSI is calculated

You never need to calculate RSI by hand, because every charting platform does it for you, but knowing the steps explains how it behaves.

1. For each candle, measure the change from the previous close. A rise is a gain, a fall is a loss, and the other value for that candle is zero.
2. Average the gains and the losses over the period, which is 14 candles by default. Wilder used a smoothed average, so each new average equals the previous average multiplied by 13, plus the latest value, all divided by 14.
3. Divide the average gain by the average loss. This ratio is called the relative strength, or RS.
4. Convert it to the index: RSI equals 100 minus 100 divided by (1 plus RS).

Here is a short example using made up numbers, not live market data. Suppose the 14 period average gain on EUR/USD is 8 pips per candle and the average loss is 4 pips. RS is 8 divided by 4, which is 2. RSI is 100 minus 100 divided by 3, or about 66.7. If the average gain and average loss were equal, RS would be 1 and RSI would sit exactly at 50. If there had been no losses at all, RSI would reach 100.

Because of the smoothing, RSI does not jump wildly on one candle. It needs a run of strong closes in one direction to reach the extremes, which is why extreme readings tell you something about the recent run rather than about a single bar.

Overbought and oversold: what 70 and 30 really mean

The classic levels are 70 and 30. Above 70 the market is called overbought and below 30 oversold. Those words cause a lot of damage, because they sound like instructions. In practice they only mean that recent gains or losses have been unusually one sided.

In a range, where price swings between clear support and resistance levels, an RSI above 70 near the top of the range can be a fair warning that the push is running out of energy. In a strong trend, the same reading often means the opposite: buyers are firmly in control. During a steady rally, RSI can stay above 70 for many candles while price keeps climbing. Selling simply because the indicator says overbought is one of the most common ways beginners end up fighting a trend.

A more useful habit is to wait for RSI to leave the extreme zone. A reading that moves above 70 and then falls back below it shows that momentum has actually started to fade, rather than just being strong. Even then, it is a reason to look closer at the chart, not a trade on its own.

Using the 50 line to read the trend

The middle of the scale is often more helpful than the edges. When RSI spends most of its time above 50, average gains are larger than average losses and the trend is generally up. When it stays below 50, sellers are stronger.

Many traders also notice that RSI tends to work within shifted ranges during trends. In a healthy uptrend, pullbacks often stop with RSI around 40 to 50 rather than falling all the way to 30, while rallies push it to 70 or higher. In a downtrend the pattern flips, with bounces stalling near 50 to 60. If an uptrend suddenly produces a pullback that drives RSI well below 40, it is a hint that the trend may be weakening. This pairs naturally with trends and moving averages: the moving average shows the direction, and RSI shows how much force is behind it.

RSI divergence explained

Divergence is when price and RSI disagree. It is the signal most experienced traders actually look for.

• Bearish divergence. Price makes a higher high, but RSI makes a lower high. The market reached a new peak, yet the move up had less momentum than the last one.
• Bullish divergence. Price makes a lower low, but RSI makes a higher low. Sellers pushed to a new bottom, but with less force than before.

Divergence is an early warning, not a reversal. A trend can show divergence several times and keep going, especially on lower timeframes. It becomes more meaningful when it appears at an obvious level on the chart, on a timeframe of an hour or higher, and when price then confirms it, for example by breaking the most recent swing low after a bearish divergence. Looking at how the candles close at that level also helps, and our guide on how to read candlestick charts covers the patterns that often appear there.

Wilder also described failure swings, which look only at RSI. In a bearish failure swing, RSI rises above 70, drops back, fails to get back above 70 on the next rally, and then falls below its previous dip. The bullish version is the mirror image below 30. Failure swings are rarer than divergence but follow the same idea: momentum is fading before price shows it clearly.

Choosing RSI settings

The default of 14 periods is the most widely used, and there is a good argument for keeping it, because it is what most other traders are looking at. Shorter settings such as 7 or 9 react faster and hit the extremes more often, which produces more signals and more false ones. Longer settings such as 21 move more slowly and reach 70 or 30 less often.

Some traders widen the levels to 80 and 20 on very active markets, so that only the most stretched moves count as extreme. Whatever you choose, keep it fixed while you test it, and read RSI on the same timeframe you use for entries. An hourly RSI and a daily RSI can tell very different stories on the same pair at the same moment.

RSI on forex pairs and on gold

On major currency pairs, RSI tends to behave well in the quieter hours, when price often moves in ranges, and becomes less reliable around big releases such as inflation data or central bank decisions, when a single candle can push it to an extreme and keep it there. It is worth checking the economic calendar before reading too much into an extreme reading just before news.

Gold (XAUUSD) trends strongly at times and can stay overbought or oversold for long stretches, particularly when the US dollar or interest rate expectations are moving fast. That makes the trend reading and divergence more useful on gold than simple 70 and 30 rules. Because gold moves several dollars in an hour, any trade idea based on RSI still needs a stop that respects its normal range and a position size worked out from that stop.

Common RSI mistakes

1. Treating overbought as a sell signal. In a trend, overbought is often a sign of strength.
2. Trading every divergence. Divergence without confirmation from price is only a warning.
3. Ignoring the bigger timeframe. An oversold reading on 5 minute candles inside a daily downtrend is usually just a pause.
4. Changing settings after every loss. Constant tweaking fits the indicator to the past and hides whether the method works.
5. Forgetting risk. No RSI reading removes the need for a stop loss and a sensible size.

A simple RSI checklist

• Decide first whether the market is trending or ranging, using price and a moving average.
• In a trend, use RSI pullbacks toward 40 to 50 (uptrend) or 50 to 60 (downtrend) as areas to look for entries in the trend direction.
• In a range, treat moves back out of the 70 or 30 zones near range edges as possible turning points.
• Look for divergence at clear levels, and wait for price to confirm it.
• Check the calendar for releases that could distort the reading.
• Set the stop where the idea is proven wrong, then size the position from that distance.

Using RSI alongside trade signals

If you follow signals, RSI is a useful way to understand the context of a trade rather than a reason to second guess it. Forexuro signals come with an entry, a stop loss and three targets, and every closed trade is listed in the public trade history, losses included. Glancing at RSI when a signal arrives can show whether the trade is joining a strong trend or catching a stretched move, which helps you understand why it may need room, and reminds you to size it from the published stop rather than from how confident the chart makes you feel.

Frequently asked questions

Keep reading

ATR indicator explained · Trends and moving averages · Support and resistance basics