What is the formula for the RSI indicator?

The RSI is a momentum oscillator that measures price changes on a 0–100 scale, with readings above 70 signaling overbought conditions and below 30 indicating oversold levels.

Aug 03, 2025 at 11:43 am

Understanding the RSI Indicator

The Relative Strength Index (RSI) is a momentum oscillator widely used in cryptocurrency trading to measure the speed and change of price movements. It helps traders identify overbought or oversold conditions in an asset’s price. The RSI operates on a scale from 0 to 100, with values above 70 generally indicating overbought conditions and values below 30 signaling oversold conditions. The core purpose of the RSI is to assess the internal strength of a price trend by comparing the magnitude of recent gains to recent losses.

The Mathematical Formula Behind RSI

The formula for calculating the RSI involves several steps and is based on the average gains and losses over a defined period, typically 14 periods. The general formula is:

RSI = 100 – (100 / (1 + RS))

Where RS stands for Relative Strength, which is calculated as:

RS = Average Gain / Average Loss

The Average Gain and Average Loss are derived from the closing prices of a cryptocurrency over the selected time frame. These averages are smoothed over the lookback period, meaning they are not simple arithmetic averages but rather adjusted to account for prior values.

Step-by-Step Calculation of RSI

To compute the RSI manually, follow these steps:

• Collect closing prices for the chosen number of periods (e.g., 14 candles on a 1-hour chart).
• Calculate price changes between each consecutive close. If the price increased, record the difference as a gain; if it decreased, record the absolute value as a loss.
• Compute the initial average gain and loss by summing the gains and losses over the first 14 periods and dividing each by 14.
• Smooth subsequent averages using the following formulas:
  • Average Gain = [(Previous Average Gain) × 13 + Current Gain] / 14
  • Average Loss = [(Previous Average Loss) × 17 + Current Loss] / 14
• Calculate RS by dividing the current smoothed average gain by the smoothed average loss.
• Plug RS into the RSI formula to get the final value.

This method ensures that the RSI responds dynamically to new price data while maintaining continuity from historical values.

Implementing RSI in Cryptocurrency Trading Platforms

Most cryptocurrency trading platforms, such as Binance, Bybit, and TradingView, have built-in RSI indicators that apply the standard 14-period formula automatically. To use the RSI on TradingView:

• Open a chart for your desired cryptocurrency pair (e.g., BTC/USDT).
• Click on the “Indicators” button located at the top of the chart.
• Search for “Relative Strength Index” in the indicator search bar.
• Select the RSI indicator to apply it to the chart.
• By default, the period is set to 14, but you can modify it in the settings.
• Adjust overbought and oversold levels if needed—common customizations include changing thresholds to 80 and 20 for less sensitivity.

The plotted RSI line will appear in a separate window below the price chart, allowing traders to visually assess momentum shifts.

Customizing RSI Parameters for Different Timeframes

While the default setting is 14 periods, traders often adjust this value based on their strategy and timeframe. Shorter periods, such as 7 or 9, make the RSI more sensitive to price changes, useful for scalping on 1-minute or 5-minute charts. Longer periods, like 21 or 28, smooth out the indicator and reduce false signals, suitable for daily or weekly charts.

To change the RSI period on Binance:

• Navigate to the charting interface.
• Click on “Indicators” at the top.
• Type “RSI” and select it from the dropdown.
• Click the gear icon next to the RSI label in the chart legend.
• In the settings panel, locate the “Length” field and input your desired value (e.g., 7).
• Close the settings window; the RSI will recalculate instantly.

This flexibility allows traders to tailor the RSI to the volatility characteristics of cryptocurrencies like Bitcoin or Ethereum.

Interpreting RSI Values in Crypto Markets

In fast-moving crypto markets, RSI values can remain in overbought or oversold zones for extended periods during strong trends. For example, during a bullish rally, Bitcoin’s RSI may stay above 70 for days without a reversal. Conversely, during sharp corrections, it may drop below 30 and remain there. This behavior highlights the importance of using RSI in conjunction with other tools.

Traders also watch for divergences between price and RSI. A bullish divergence occurs when the price makes a lower low but the RSI forms a higher low, suggesting weakening downward momentum. A bearish divergence happens when the price reaches a higher high while the RSI makes a lower high, indicating potential exhaustion.

Frequently Asked Questions

Q: Can the RSI be used on non-candlestick charts?

Yes, the RSI can be applied to any time-series price data, including line and area charts. However, candlestick charts are preferred because they provide more context about price action, such as wicks and body size, which help confirm RSI signals.

Q: What happens if the average loss is zero in the RSI calculation?

If the average loss is zero, the RS value becomes undefined due to division by zero. In practice, most platforms assign an RSI value of 100 in this scenario, indicating extreme upward momentum with no losses over the period.

Q: Is the RSI effective for all cryptocurrencies?

The RSI works best on assets with sufficient trading volume and liquidity. For low-cap altcoins with erratic price swings, the RSI may generate false signals due to manipulation or low market depth. It is more reliable when used on major pairs like BTC/USDT or ETH/USDT.

Q: How often should I recalculate the RSI manually?

Manual recalculation is unnecessary for active trading. Automated platforms update the RSI in real time. However, understanding the manual process helps in grasping how smoothing affects the indicator’s responsiveness and lag.