The Average Directional Index (ADX) measures how strong a trend is, regardless of whether the price is moving up or down. It does not tell you the direction of a trend on its own. Instead, it works alongside two companion lines, the +DI and -DI, which handle direction. Together, these three lines help you decide whether a market is trending strongly enough to trade with momentum strategies or whether it’s moving sideways and better suited to range-bound approaches.
What the Three Lines Tell You
Most charting platforms plot the ADX as a system of three lines. Understanding what each one does is the foundation for using the indicator correctly.
The ADX line itself is a single value between 0 and 100 that represents trend strength. A rising ADX means the trend, up or down, is gaining momentum. A falling ADX means momentum is fading. Crucially, the ADX says nothing about the actual price of a security or whether the trend is bullish or bearish.
The +DI (positive directional indicator) measures upward price movement. When +DI is above -DI, buyers are in control and the trend direction is up.
The -DI (negative directional indicator) measures downward price movement. When -DI is above +DI, sellers are in control and the trend direction is down.
The standard setting on most platforms is a 14-period lookback. Some traders shorten this to 7 or 10 periods for faster signals on shorter timeframes, but the default works well for swing trading and daily charts.
Reading ADX Strength Levels
The most widely used threshold is 25. When the ADX is above 25, the market is considered to be in a meaningful trend. When it’s below 20, the market is generally range-bound or choppy, meaning prices are drifting sideways without conviction. The zone between 20 and 25 is ambiguous and often best treated as a “wait and see” area.
Here’s a practical breakdown of the ranges:
- 0 to 20: Weak or absent trend. Price is likely chopping sideways. Trend-following strategies tend to produce false signals here.
- 20 to 25: A trend may be emerging, but it’s not confirmed yet.
- 25 to 50: A solid trend is in place. This is the sweet spot for trend-following entries.
- 50 to 75: An extremely strong trend. These readings are less common and often occur during sharp breakouts or sell-offs.
- Above 75: Rare. When the ADX reaches this territory, the trend is often near exhaustion rather than just getting started.
One important nuance: a falling ADX does not mean the trend has reversed. It means the trend is losing momentum. Price can continue rising even as the ADX drops from 40 to 30, because the uptrend is still intact, just slowing down. Think of it like a car that’s still moving forward but easing off the gas.
Using DI Crossovers for Direction
The +DI and -DI lines crossing each other generate the directional signals. When +DI crosses above -DI, it signals that upward price movement is overtaking downward movement, which is a potential buy signal. When -DI crosses above +DI, it’s the opposite, a potential sell or short signal.
These crossovers are most reliable when the ADX is also rising and above 25. A +DI/-DI crossover while the ADX sits below 20 is happening in a trendless market and is far more likely to be a false signal. This is the core filtering rule of the ADX system: use the crossovers for direction, but only act on them when the ADX confirms that a real trend is present.
A straightforward entry approach looks like this: wait for +DI to cross above -DI, then confirm that the ADX line is above 25 (or rising toward it). Enter the trade in the direction of the crossover. For exits, watch for the opposite crossover or for the ADX to peak and start declining, which signals that the trend’s momentum is fading even if price hasn’t reversed yet.
Confirming Breakouts
One of the most practical uses of the ADX is filtering breakouts. When a stock or currency pair breaks above a resistance level, you want to know whether the move has real momentum behind it or whether it’s a false breakout that will quickly reverse.
If the ADX is rising from below 20 toward 25 at the same time a price breakout occurs, that’s a sign the market is transitioning from a range-bound state into a trending one. This is often where the strongest trend-following trades begin. The combination of a price breakout with an ADX that’s moving from the teens into the 25+ zone gives you two independent pieces of evidence that the move is legitimate.
Conversely, if price breaks out but the ADX stays flat below 20, treat the breakout with skepticism. The indicator is telling you that directional momentum hasn’t actually picked up, even though price made a new high or low.
Spotting Momentum Divergence
Divergence between price and the ADX can warn you that a trend is weakening before the price chart makes it obvious. The most common form is negative divergence: price makes a higher high, but the ADX makes a lower high. This tells you that while price is still advancing, the underlying momentum driving that advance is shrinking.
Negative divergence doesn’t mean you should immediately reverse your position. It’s a caution signal. When you see the ADX peaking lower on each successive price high, it often means the trend is in its later stages. You might tighten your stop-loss, take partial profits, or simply stop adding to the position.
The same logic applies in downtrends. If price makes a lower low but the ADX peaks lower than it did on the previous leg down, selling pressure is weakening even though price is still falling.
When the ADX Falls Short
The ADX is a lagging indicator. It’s built on a moving average of price range expansion over the past 14 periods (by default), so it always confirms a trend after it has already started. You won’t catch the exact bottom or top of a move using the ADX alone. That’s by design: the indicator sacrifices speed for reliability.
In range-bound or choppy markets, the ADX is largely useless for generating trade signals. The +DI and -DI lines will cross back and forth frequently without the ADX rising above 25, producing a string of false signals. If you notice the ADX spending weeks below 20, it’s telling you to stop looking for trends and consider mean-reversion or range-trading strategies instead.
The ADX also cannot tell you anything about price levels. An ADX of 40 doesn’t mean the stock is expensive or cheap. It just means whatever direction the price is moving, it’s doing so with strong momentum. Pair the ADX with price-based tools like support and resistance levels, moving averages, or volume analysis to get a more complete picture.
Combining ADX With Other Indicators
Because the ADX only measures trend strength and direction (through the DI lines), it pairs well with indicators that cover what it misses. A moving average crossover system, for example, generates buy and sell signals based on price direction. Adding an ADX filter (only take the signal when ADX is above 25) can reduce the number of losing trades that occur during sideways markets.
The Relative Strength Index (RSI) is another natural companion. RSI identifies overbought and oversold conditions, which are most relevant in range-bound markets. If the ADX is below 20, RSI signals carry more weight. If the ADX is above 25, trend-following signals carry more weight. Using both lets you adapt your strategy to the current market environment rather than applying one approach blindly.
Volume indicators also complement the ADX well. A rising ADX with increasing volume gives you extra confirmation that the trend has real participation behind it. A rising ADX on declining volume may signal that the trend is thinning out and could reverse sooner than the ADX alone would suggest.
Practical Setup Steps
On most charting platforms (TradingView, thinkorswim, MetaTrader), the ADX is listed as “ADX” or “DMI” (Directional Movement Index) in the indicator library. Some platforms plot all three lines by default. Others plot only the ADX line, and you’ll need to enable +DI and -DI separately or select the full DMI version.
Start with the default 14-period setting. Once you’re comfortable reading the indicator, you can experiment: a shorter period (7 to 10) makes the lines more responsive but noisier, while a longer period (20 to 25) smooths out the signals but reacts more slowly. For daily charts on stocks or ETFs, 14 is a solid starting point. For intraday charts (5-minute, 15-minute), some traders prefer a shorter lookback to keep up with faster price action.
As a general workflow: check the ADX value first to determine if the market is trending. If it’s below 20, set aside your trend-following strategies. If it’s above 25, look at which DI line is on top to identify the direction, then use your preferred entry method (price breakout, moving average crossover, pullback to support) to time the trade.