When I was recently looking at technical indicators, I found that the DMI tool is actually quite useful—especially for judging trends. Many people may not be very familiar with it, but if you often trade based on trends, the DMI indicator’s trend judgment can give you a lot of help.

DMI stands for Directional Movement Index, created by Wilder in 1978. In simple terms, it uses three lines to read the market: the +DI line shows the strength of upward movement, the -DI line shows the strength of downward movement, and the ADX line measures how strong the trend is. This combination quantifies the strength of a trend, which is meaningful for managing risk.

How do you use it? I’ve summarized three main scenarios.

The first is determining whether a trend even exists. If the ADX value is above 25, it means the market has a clear direction; if it’s below 25, the market is in a range (consolidation) and there’s no real trend to speak of. This is important for deciding whether to get involved, because some market action is just sideways—if you force yourself to chase against the move, you’re more likely to get trapped.

The second is finding buy and sell points. When +DI crosses above -DI, it’s a buy signal, suggesting the uptrend may be starting. Conversely, when +DI breaks below -DI, it’s a sell signal. I’ve seen an example with Apple stock: in early November, when +DI crossed above -DI, that was the buy signal, and afterward the price rose to over $199. Even though there was a later pullback, this signal still captured the main upswing.

The third is divergence signals. If the price makes a new high but the ADX and +DI are actually weakening, this is called a top divergence, indicating that the upward momentum is fading and a shift may be coming. Similarly, if the price makes a new low but the -DI doesn’t follow through with a new low, this is called a bottom divergence, suggesting a rebound may be on the way. The USD/JPY pair showed a clear top divergence during last year’s rally, and afterward it indeed topped out and fell.

Of course, DMI isn’t perfect. Its calculations are based on the average change of candlesticks over a period of time, so it isn’t sensitive enough, and sometimes it can miss some swings. But you can adjust parameters—for example, changing the period from 14 to 9—or combine it with indicators like MACD and RSI, which improves the results considerably. Some people also add pattern analysis to confirm take-profit and stop-loss levels.

Honestly, the biggest advantage of the DMI indicator in judging trends is that it quantifies strength, helping you gauge your win rate. Especially when trading long-term, one-directional moves, it can provide a lot of useful reference. But remember, in sideways markets it tends to produce false signals, so it’s best not to rely on it alone—using it together with other tools will work better.