Understanding the Relative Strength Index

The Relative Strength Index (RSI) is a popular and powerful tool used by traders for technical analysis. Even with many new indicators available, the RSI stands out because it's simple to use, has been around for a long time and works well. In this guide, we'll explain what RSI is and the best way to interpret and use it. Please note, this is not financial advice but an explanation of the mechanisms behind the RSI and its application in trading.

The Relative Strength Index, or RSI, is a momentum oscillator that measures the speed and change of price movements. Developed by J. Welles Wilder Jr, the RSI was introduced in his book New Concepts in Technical Trading Systems in 1978.

The RSI is displayed as an oscillator that is visible on a separate window of the chart. The indicator is bound between 0 and 100 and assists traders by raising awareness that an asset is potentially trading in overvalued or undervalued territory based on recent price movements.

Think of the RSI as a speedometer for a stock or asset. It helps market participants see how quickly the price is changing and how the average gains compare to the average losses.

The RSI is calculated using a pretty straightforward formula:

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

Where RS (Relative Strength) is the Average gain of up periods during the specified time frame divided by the Average loss of down periods during the specified time frame.

RS = Average Gain/Average Loss

Average gain: sum of gains over X periods/X

Average loss: sum of losses over X periods/X

The X is typically set to 14 periods by default, but you can tweak it to fit your trading style, something we will cover further into this article.

Fortunately, the charting packages on most trading platforms perform these calculations automatically so you don’t have to.

The Relative Strength Index (RSI) measures the speed and size of price movements on a scale from 0 to 100. Think of it as a speedometer for market momentum. When the RSI is above 70, it signals that prices might be overbought or overvalued. Conversely, when an asset's RSI falls below 30, it indicates that the asset may be oversold or undervalued. Market participants use these signals as warnings, as they often precede price retracements.

It's important to note that prices can still rise in the "overbought" zone or fall in the "oversold" zone. Therefore, combining RSI with other indicators can improve accuracy and success rates.

A common mistake traders make is to buy or sell immediately when the RSI enters an overbought or oversold territory. A better approach is to wait until the RSI crosses back below 70, indicating a potential shift in momentum from buyers to sellers.

The neutral zone around 50 indicates a balanced market, akin to a “Goldilocks” scenario—not too bullish or bearish. When the value exceeds 50, it suggests that gains are outpacing losses, hinting at an upward trend. Conversely, a value below 50 indicates that losses are surpassing gains, signaling a downward trend. Although the Relative Strength Index (RSI) is not flawless, it serves as a valuable instrument for spotting potential market movements.

The RSI is helpful for market participants in identifying trends. In a strong uptrend, the RSI typically stays between 40 and 90, with the 40-50 range acting as support. In a strong downtrend, the RSI ranges from 10 to 60, with the 50-60 range serving as resistance.

The centerline of the RSI, marked at 50, is crucial for trend identification. When the RSI crosses above 50, it indicates a bullish trend; crossing below 50 signals a bearish trend.

In a downtrend, an RSI that peaks and fails to rally above the 50-60 level implies the continuation of the trend. Traders can draw trendlines on the RSI chart, which helps to highlight the market’s trend direction and signals potential breakouts when the RSI breaks through these lines.

The retracements towards the RSI 50-60 level is not necessarily used as confirmation of a potential trade setup but may be used by market participants in determining when to exit a position. It is important to note that a break above the 50-60 level on the RSI is a sign of shifting momentum and a potential trend change from a downtrend to an uptrend.

Looking at the chart example below, the moment the RSI broke above the green block we saw a change in trend.

Traditionally the RSI adopts a 14 period setting which means it looks at price changes over the last 14 trading periods. Now, I say periods because if you are using a daily chart the RSI would represent the last 14 days but on a 1-hour chart the RSI setting will correspond to 14 one-hour candlesticks.

This is the most popular setting because it strikes a good balance between being responsive and dependable for general market analysis. It is effective for most trading strategies and timeframes.

Adjusting the RSI settings can help tailor the indicator to different trading styles and timeframes. The standard overbought and oversold levels of 70 and 30 are just guidelines and not strict rules. Some traders adjust these levels based on their risk tolerance or the market's volatility. It's about finding what works best for you and your strategy.

For instance, in a very volatile market, you might raise the overbought level to 80 or 90 to stay in trades longer. In a calmer market, you could lower the oversold level to 20 or 10 to spot potential reversals sooner.

The standard RSI calculation typically uses a 14-period time frame, but you can adjust this to better suit your trading horizon. Using a shorter period, like 9 or 7, will make the RSI more responsive to recent price changes.

Examples of this are as follows:

1. Shorter Periods
   Another popular setting used is 7 or at times 9 as well. By shortening the number of periods, the RSI becomes more sensitive and thus provides more signals. Usually preferred by those seeking a day trading approach. The downside to this is that you market participants may end up receiving a lot more false signals.
2. Longer Periods
   Increasing the number of periods makes the RSI less reactive, which smooths out the indicator and reduces the number of signals. This is helpful for long-term traders or investors who want to ignore short-term market fluctuations and concentrate on stronger trends. The more popular used settings are 14 or 21.

The Relative Strength Index (RSI) is a popular momentum oscillator that offers several advantages for trading financial markets:

1. Simplicity: The RSI's simplicity stems from its clear and concise signals, as well as its ease of interpretation.
2. Identifying Overbought and Oversold Conditions: It remains one of the simplest methods to alert traders to focus on a particular asset. When an asset enters the overbought or oversold zones around 70 and 30, it is easy to notice when the RSI reverses out of these zones, indicating a shift in momentum.
3. Divergence Detection: The RSI can indicate when price and momentum are misaligned. If the RSI increases while the price decreases, it signals a bullish divergence. Conversely, if the RSI decreases while the price increases, it signifies a bearish divergence.
   
   

The RSI has many advantages but as traders you have to make sure you understand the limitations and disadvantages that crop up.

1. False Signals/Counter Trend Trading: In trending market conditions, the RSI can stay in the overbought or oversold zones for extended periods. This means that the overbought and oversold levels don't necessarily provide reliable signals, as taking a trade while the RSI is in these zones could result in a "false signal" due to trading against the trend.
2. It is a Lagging Indicator: It's important to remember that the RSI is a lagging indicator. This means it may not provide the most timely signals, particularly in fast-moving markets. By the time the RSI responds, the opportunity might have already passed. Therefore, patience is crucial, and waiting for the right setups is essential.
   
   

Overall, the RSI indicator is a valuable tool for traders seeking to analyze market momentum and spot potential trading opportunities. However, it's crucial to remember that RSI should not be used alone and should be combined with other forms of analysis for more informed decision-making.

The Relative Strength Index (RSI) can be your secret weapon for pinpointing market momentum and spotting profitable opportunities. Don't let fear or uncertainty hold you back.

Start your risk-free journey today and practice the RSI strategies firsthand.

Apply for a demo with OANDA and start your journey now.

Disclaimer

This article is for general information purposes only, not to be considered a recommendation or financial advice. Past performance is not indicative of future results.

Opinions are the author's; not necessarily that of OANDA Corporation or any of its affiliates, subsidiaries, officers or directors.

Leveraged trading in foreign currency contracts or other off-exchange products on margin carries a high level of risk and is not suitable for everyone. We advise you to carefully consider whether trading is appropriate for you in light of your personal circumstances. You may lose more than you invest. We recommend that you seek independent financial advice and ensure you fully understand the risks involved before trading.