RSI Indicator Explained: How to Read Overbought and Oversold Signals in Forex Trading

Open almost any trading chart and you'll find RSI in the indicator list. It's one of the most popular tools in forex, and also one of the most misunderstood.

Many beginners see RSI hit 70 and sell immediately, only to watch the price keep climbing. This guide explains what RSI actually tells you and how to use it sensibly.

What Is the RSI Indicator?

The Relative Strength Index, or RSI, is a momentum indicator. It compares the size of recent gains with the size of recent losses to show how strong a move has been.

It was developed by J. Welles Wilder Jr. and introduced in his 1978 book, New Concepts in Technical Trading Systems. Wilder used 14 periods, and that remains the default setting on most platforms today. On a 1-hour chart, that means the last 14 hours. On a daily chart, the last 14 days.

RSI is shown as a line in a separate window below your chart, moving between 0 and 100.

How RSI Is Calculated

You don't need to calculate it yourself, because your platform does it for you. But it helps to understand the idea:

RSI = 100 − (100 ÷ (1 + RS))

Where RS is the average gain divided by the average loss over the chosen period.

In simple terms: if recent candles have mostly closed higher, RSI rises. If they have mostly closed lower, RSI falls.

RSI Overbought and Oversold Levels

"Overbought" means price has risen quickly and may be due a pause or pullback. "Oversold" means price has fallen quickly and may be due a bounce.

Watch Out: In a strong trend, RSI can stay above 70 or below 30 for a long time. Selling every time RSI hits 70 in a strong uptrend is one of the most common beginner mistakes.

RSI moves between 0 and 100. Above 70 is traditionally overbought, below 30 is oversold.

How to Use RSI in Forex

1. Use it with the trend.

In an uptrend, look for RSI to dip towards 40 or the oversold area during pullbacks as a possible buying opportunity, rather than selling at 70. In a downtrend, do the opposite.

2. Combine it with key levels.

An oversold RSI reading at a strong support level is more meaningful than an oversold reading in the middle of nowhere.

3. Watch the 50 line.

RSI above 50 suggests buyers have more control. Below 50 suggests sellers do. Some traders use this as a simple trend filter.

4. Confirm before acting.

Wait for price to show a reaction, such as a strong candle in your direction, before entering.

Quick Tip: Stick with the default 14 setting while you learn. Changing settings constantly makes it harder to understand what the indicator is telling you.

RSI Divergence Made Simple

Divergence happens when price and RSI disagree.

•     Bearish divergence: price makes a higher high, but RSI makes a lower high. The uptrend may be losing strength.

•     Bullish divergence: price makes a lower low, but RSI makes a higher low. The downtrend may be losing strength.

Wilder saw divergence as an important warning sign. Still, it is a warning, not a guarantee. Trends can continue even after divergence appears.

Bearish divergence: price makes a higher high, but RSI makes a lower high, a sign the move may be losing strength.

Common RSI Mistakes

•     Treating 70 as an automatic sell signal and 30 as an automatic buy signal.

•     Using RSI alone without looking at the trend or price levels.

•     Trading against a strong trend because RSI looks "too high."

•     Changing settings after every losing trade.

Forgetting risk management. No indicator removes the need for a stop loss