Recently studying technical analysis in the crypto space, I found that many people don't quite understand the RSI indicator. How to interpret RSI is actually a good question, because when used correctly, this tool can indeed help determine buy and sell opportunities.

First, let's talk about the essence of RSI. It is essentially a momentum oscillator used to measure the magnitude and speed of an asset's price changes over a period of time. For example, if BTC rises 5% in 9 days, RSI not only shows this increase but also reflects whether the rise is gradual or rapid, which is very helpful for judging market strength. In simple terms, RSI reflects the relative strength between bulls and bears at different points in time.

When it comes to how to read RSI, many people's main concern is the three lines. The white line is usually the 6-day moving average, the yellow line is the 12-day, and the purple line is the 24-day. Each has its purpose: the 6-day line reacts most sensitively to price changes, suitable for short-term trends; the 12-day is for medium-term reference; the 24-day is used to observe long-term trends. My personal habit is to first look at the 24-day line to determine the overall direction, then use the 6- and 12-day lines to find specific entry and exit points.

Regarding buy and sell signals, there are several classic patterns worth noting. When the 6- and 12-day RSI lines both cross above the 24-day line near the 50 level, forming a golden cross, it is usually a good buy signal, indicating that short-term and medium-term trends are starting to strengthen. Conversely, if the 6- and 12-day lines cross below the 24-day line from above, forming a death cross, it’s time to consider selling.

Another very important concept is overbought and oversold. RSI ranges from 0 to 100, with 50 often serving as the dividing line between bullish and bearish. When RSI exceeds 70, the market may be in an overbought state, with limited upside; when RSI drops below 30, the market may be oversold, with limited downside. These thresholds are adjusted for different timeframes—for example, 14-day periods typically use 70 and 30, but shorter periods like 9 days are more sensitive and often use 80 and 20.

RSI interpretation also involves a phenomenon called divergence. This is one of RSI's most valuable features. Top divergence occurs when the price hits a new high but RSI fails to surpass the previous high, often indicating weakening upward momentum. Bottom divergence is the opposite: the price makes a new low but RSI does not, suggesting diminishing downward strength and a potential rebound. However, be cautious: in strongly trending markets, divergence signals may be less reliable.

In terms of calculation, RSI isn't complicated. Choose a period, such as 14 days, calculate the average gains and average losses over that period, then divide the average gain by the sum of average gain and average loss, and multiply by 100 to get the RSI value. For example, if over 14 days there are 9 up days with a total gain of 28%, the average daily gain is 2%; 5 down days with a total loss of 7%, average daily loss is 0.5%. RSI would be 2% divided by (2% + 0.5%) times 100, approximately 66.7. In practice, most trading platforms have this indicator built-in, so you can just select it directly without manual calculation.

Honestly, there is no absolute answer to how to interpret RSI, because it has its limitations. It only reflects past price movements and does not consider the order of rises and falls. Also, in strongly trending markets, RSI can become dull, staying in extreme zones for a long time and losing its reference value.

Most importantly, never rely solely on RSI for trading decisions. I recommend combining RSI with candlestick patterns, volume, support and resistance levels. For example, when the market is sideways, if the price hits previous support or resistance and RSI is at a high or low, the signals become more reliable. Adding candlestick patterns like hammers or hanging man increases accuracy.

Be especially cautious of the risks brought by RSI dulling. In strong upward or downward trends, RSI may stay above 80 or below 20 for extended periods. Blindly chasing trades in such conditions can easily lead to being caught. My approach is to draw support and resistance levels first; if the price just tests higher levels slightly, be extra cautious and avoid chasing blindly. Remember: it’s better to miss a move than to chase bad trades.

In summary, the key to reading RSI is understanding its core principle—knowing when it has high reference value and when it might lead you into traps. When combined with other indicators and fundamental analysis, RSI can indeed help us better grasp market rhythm. Lastly, remind yourself that technical analysis isn’t 100% accurate, but mastering its scope and methods is very helpful for daily observation and decision-making.