Recently, a friend asked me how to quickly determine if the market is overreacting, and that made me think of the RSI indicator. Honestly, when used correctly, it can save a lot of false signals, but many people get caught by fake signals as they use it more and more.

RSI stands for Relative Strength Index, and its core logic is quite simple—it's a number between 0 and 100 used to measure the strength of upward momentum versus downward momentum over a certain period. The closer the value is to 100, the stronger the upward momentum; the closer to 0, the more dominant the downward pressure. My habit is to be cautious when RSI exceeds 70, as it usually indicates the market is overly optimistic and a rebound risk is brewing; conversely, when RSI drops below 30, I pay attention to potential reversal opportunities.

But here’s a trap—overbought and oversold conditions do not necessarily mean the market will reverse. They only indicate that the market has overreacted in the short term. I’ve seen too many people go short as soon as RSI > 70, only to get squeezed out in a strong trend. So the key is to use RSI in conjunction with other signals.

Regarding the calculation of RSI, I was initially intimidated by the formula, but later I realized the logic isn’t complicated. The basic steps are to select a time period (default is 14 candles), then calculate the average gain and average loss over that period, divide the average gain by the average loss to get the RS value, and finally plug it into the RSI formula to get a value between 0 and 100. If you want to understand the details of the RSI formula more deeply, the core is that this ratio reflects the comparison of bullish versus bearish forces.

Parameter settings greatly affect the sensitivity of the indicator. I adjust them based on different timeframes—using RSI 6 for short-term trading to be more sensitive and catch entry points faster, though it also produces more false signals; for medium to long-term swing trading, the default RSI 14 is most balanced; for daily or weekly charts, RSI 24 is more stable, with less noise but also fewer signals. There’s no absolute best parameter; the key is to find settings that suit your trading style.

Besides overbought and oversold signals, I pay more attention to RSI divergence. This occurs when the price makes a new high or low, but RSI fails to follow, or even moves in the opposite direction. Bearish divergence (price makes a new high but RSI declines) usually indicates weakening upward momentum, while bullish divergence (price makes a new low but RSI rises) suggests diminishing downward pressure. TradingView has an automatic divergence detection feature, which is quite convenient to use.

Another often overlooked method is using the RSI’s 50 midline to determine trend direction. When RSI crosses above 50, it generally indicates a bullish trend is starting; crossing below suggests a bearish trend may be taking over. To avoid too much noise, I look at the RSI 24 for this kind of midline crossover.

Finally, I want to remind you that although RSI is useful, it’s not万能. In strong trending markets, false signals are most common. Many traders also make the mistake of confusing timeframes—seeing an oversold signal on the 15-minute chart and entering a long position without noticing that the daily RSI has already broken below the midline, causing the smaller timeframe signal to be suppressed. Therefore, it’s essential to combine RSI with MACD, moving averages, or candlestick patterns for confirmation to improve success rates. While the logic behind the RSI formula is scientific, markets are always more complex than any indicator. Maintaining humility is key to long-term trading.