Relative Strength Index

The RSI, introduced in 1978, is a highly popular and widely used technical indicator in global financial markets, particularly in the stock market, making it one of the most commonly employed tools in technical analysis

6 minutes


J. Welles Wilder Jr., a mechanical engineer, technical analyst, and author of popular books on technical analysis, including “New Concepts in Technical Trading Systems,” developed the Relative Strength Index (RSI) in 1978. Since its introduction, the RSI has become a widely used momentum indicator in technical analysis.

The RSI is a technical analysis tool that measures the strength of a security’s price action momentum by comparing its upward movements to its downward movements over a specified period. The RSI is calculated by dividing the average of the security’s upward price movements by the average of the security’s downward price movements over the chosen period. The result is then converted into a value ranging from 0 to 100. The RSI is commonly used to identify overbought and oversold market conditions and generate trading signals.

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How is the RSI computed?

The RSI is computed as follows:

Choose a time period

Start by selecting a time period for the RSI calculation. Traders usually use 14 days, but this can be adjusted based on individual preferences.

Calculate the average gain and loss

Determine the average gain and loss for the selected period. The average gain is the sum of gains divided by the number of periods, while the average loss is the sum of losses divided by the number of periods.

Average Gain = [(Sum of Gains over the last 14 periods) / 14]

Average Loss = [(Sum of Losses over the last 14 periods) / 14]

Calculate the Relative Strength

The Relative Strength (RS) is the ratio of the average gain to the average loss.

RS = Average Gain / Average Loss

Compute the RSI

Use the formula below to calculate the RSI.

RSI = 100 - [100 / (1 + RS)]

The RSI ranges between 0 and 100. If it is above 70, it indicates an overbought condition, while a reading below 30 is considered oversold. Traders use these levels to identify potential reversal points in the price movement of the security. However, it’s important to note that the RSI is not a foolproof indicator and should be used in conjunction with other tools to confirm signals.

The RSI is a number between 0 and 100. A reading above 70 is considered overbought, while a reading below 30 is considered oversold. Traders use these levels to identify potential reversal points in the price movement of the security.

How to use the RSI to trade?

RSI plotted along with the SuperTrend indicator in ChartAlert

If you’re interested in using the RSI to trade, here are some steps to consider:

Choose a time frame

The time frame you use to calculate the RSI is crucial. Although traders generally use a 14-period RSI, you can adjust this to suit your trading style.

Interpret the RSI

The RSI value ranges from 0 to 100. If the RSI is above 70, it can suggest an overbought condition, while a reading below 30 may indicate an oversold condition. However, you can also use other levels, such as 80 and 20, to define overbought and oversold conditions.

Identify divergences

Keep an eye out for divergences between the RSI and the security’s price. Divergences occur when the RSI moves in the opposite direction of the price, indicating a potential reversal.

Trade based on RSI levels

If the RSI is above 70, it may indicate an overbought condition and a potential reversal. Conversely, if the RSI is below 30, it may indicate an oversold condition and a possible buying opportunity.

Use RSI in combination with other indicators

While the RSI is a helpful tool, it’s best to use it in conjunction with other indicators to confirm trading signals.

It’s important to remember that while the RSI is a valuable technical analysis tool, it’s not without limitations. As with any technical analysis tool, it’s advisable to use the RSI in conjunction with other indicators and follow proper risk management techniques to manage trading risk.

Can RSI be used both for trading and investing?

The RSI is primarily used by traders to identify potential overbought or oversold conditions in a security over the short term. While it may be useful for identifying entry and exit points for short-term trades, it may not be as relevant for long-term investing.

Long-term investors typically focus on fundamental characteristics of a company, such as its financial performance, industry position, and growth prospects. They also consider macroeconomic trends and overall market conditions. The RSI is not designed to provide insight into these factors, making it less relevant for long-term investing. Instead, long-term investors may want to consider other indicators, earnings growth, revenue growth, dividend yield, and price-to-earnings ratios, to evaluate the long-term potential of a company.

Despite this, the RSI can still be a useful tool when included in a broader analysis of a security, especially if you’re considering a short-term trading strategy. However, it shouldn’t be the sole determinant of your investment decisions, and it’s always advisable to consider multiple factors when evaluating potential investments.

Advantages & limitations of using RSI

Here are some advantages and limitations of using RSI in technical analysis:


  • RSI can provide a quick and easy-to-understand snapshot of a security’s momentum and overbought/oversold conditions.
  • RSI is a widely used technical analysis tool, so traders can easily find resources and strategies for using it effectively.
  • RSI can be used in conjunction with other indicators to confirm trading signals and provide a more complete picture of the market.


  • RSI is a short-term technical analysis tool, so it may not be as useful for long-term investing or evaluating the fundamental characteristics of a company.
  • RSI can generate false signals, particularly in markets that are trending strongly in one direction.
  • RSI can be impacted by sudden price spikes or drops, which may skew the calculation and generate inaccurate signals.
  • RSI is just one tool in a trader’s toolbox and should not be relied upon as the sole determinant of investment decisions.

RSI is a popular technical analysis tool used by traders to measure the strength of a security’s price action and identify potential entry and exit points. It provides a simple and effective way to determine overbought and oversold conditions, which can help traders make informed decisions and manage risk. With its ease of use and versatility, RSI can be a valuable addition to a trader’s toolbox, particularly for those who prefer short-term trading strategies. By incorporating RSI into their analysis, traders can gain a better understanding of market trends and make more confident trades.

However, please note that RSI, like any other technical analysis tool, is not a perfect indicator and has its limitations. Trading based solely on RSI signals can result in losses, and it is advisable to use it in conjunction with other technical analysis tools and follow risk management techniques to manage trading risk. Past performance is not indicative of future results. Any investment or trading decision you make is solely your responsibility, and you should carefully consider all factors before making any trading decisions.

For examples of customizable Relative Strength Index (RSI) factory scans that can be edited, modified, or revised, and subsequently scanned through ChartAlert’s native stock screener or technical analysis scanner, click here.

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