Ever wondered why some traders can buy significant market trends while their counterparts seem stuck in a sideways overlapping price action? The ability to distinguish between market trends and non-trends is often the secret to their success.

Enter the Average Directional Index (ADX). Introduced to the trading world by J. Welles Wilder Jr. in 1978. The ADX is respected as an indicator of trend strength. Whereas the ADX does not tell you if prices are moving up or down, it does tell you the strength of the move.

If you're frustrated with fake breakouts, false reversals, or a lack of price action, the ADX can help you filter market noise and focus on high-probability setups.

What is the Average Directional Index (ADX)?

The ADX is one of Wilder's Directional Movement System, which includes two other indicators: +DI (Positive Directional Indicator) and –DI (Negative Directional Indicator). When coupled with these other two indicators, the ADX will help traders do the following:

• Establish whether the market is trending.

• Identify the strength of the trend.

• Establish when to enter or exit trades.

Just consider the ADX your trend strength meter. A high ADX signifies strong directional movement in one direction, a low ADX signifies a lot of indecision, and choppy overlapping price action.

How is ADX Calculated? (The simplified version)

Although your trading platform will calculate the ADX automatically, you should understand the math involved so you can trust the indicator:

• Establish Directional Movement (DM):

        1. UpMove = Today's High − Yesterday's High

        2. DownMove = Yesterday's Low − Today's Low

• The larger number becomes +DM or –DM.

Determine the +DI and –DI:

These are derived by smoothing the DM over a typical 14-period average and dividing these by the Average True Range (ATR).

• Derive the ADX:

Finally, the ADX is derived by smoothing the average of the absolute difference between the +DI and –DI divided by the sum of the two components, multiplied by 100.

This will yield a number between 0 and 100.

How to Interpret ADX Values

Understanding ADX levels is the key to using it effectively:

Pro Tip: The 25 level is significant to many traders, and an ADX reading higher than 25 indicates that a trend is probably starting to build.   

Real-Life ADX Examples  

Example 1: Participating in a Strong Uptrend.  

Let’s say that ADX rises from 22 to 35 and that +DI > -DI. This sends a message to traders that buyers are controlling the trade and that a trend will begin to build. A trader might:  

• Enter a trade when the price breaks above resistance.   

• Place a stop-loss just under recent support.  

• Use trailing stops to ride the uptrend as long as ADX keeps advancing.  

Example 2: Not Participating in a False Break

Let’s say price spikes above resistance for a short period, and the ADX is at 15. It is great to see the break of resistance, but it signals that no momentum was behind the “breakout.” So by not taking the trade, you would save yourself from a frustrating loss.   

Popular Arguments with ADX Trading  

These are a few solid ways to utilise ADX:   

a) Trend Confirmation  

• Buy signal: ADX > 25 and +DI crosses -DI moving up from below.  

• Sell signal: ADX > 25 and -DI crosses +DI moving down from below.  

b) Using ADX to Avoid Choppy Markets

When ADX is below 20, this is a great time to pull back on any trend following system. In these low momentum movements, choppy, range-based trading, a buy near support and sell near resistance strategy, is more effective.  

c) Pairing ADX with RSI 

If using ADX in combination with the Relative Strength Index (RSI), this can be a good one-two punch to trade:  

• ADX tells us there is a strong trend.  

• RSI provides us with overbought or oversold extremes for timing entry.  

• Using this indicator combo appears to be an outstanding correlation to timely and profitable market entries.  

d) Trailing Stop with ADX

When ADX is increasing, this indicates you can let profits run. As price declines with ADx, it generally signals a weakening trend. If the price tends to weaken momentum, you are well-positioned to use tighter stops, ensuring you do not face significant losses.

Shortcomings of ADX  

While generally, a powerful indicator, ADX, is by no means perfect:  

• Lagging Indicator: ADX can lag upheavals in market structure as it measures averages or trends in motion.  

• No Direction: ADX measures the strength of trend momentum but provides no directional context.  

• False Signals: If used alone, ADX can generate false signals in a ranging market.   

Solution: Get in the habit of using the ADX with both +DI/-DI indicators or with other indicators for additional contexts, like other oscillators (RSI, MACD) or volume indicators.  

Pro Tips for Using ADX Like a Pro

• Leave at Default Settings.: The default is set at 14 periods, but you can play with shorter periods (like 7 or 10) as this can mimic faster moving averages.  

• Watch for Divergences: If there is a new high in price with an ADX falling, then there may be weakening momentum to the trend.  

• Use Further Out Timeframes: Watch the ADX on higher timeframes to help confirm the trend is being confirmed by prices moving, or preparing to move, if the larger timeframe trend structures suggest this.  

• Do Not Trade ADX Alone: If you agree that the best ways to assess trading opportunities are through a family of indicators, one should only evaluate ADX along with +DI/-DI.   

Summary  

As a tool to analyse trend-directional momentum, the Average Directional Index (ADX) is more than a meaningless line on a chart; it is a momentum directional guide and is ever-present. By measuring the strength of the trend, ADX can lend traders confidence to:  

• Know when to enter, to hop on a move.  

• Know when not to trade, if there is a false breakout.  

• Know when to exit, before the momentum of the trend disappears.  

While ADX is not foolproof as a standalone tool in all trading situations, it serves as a robust directional market (leader) board when used alongside +DI and -DI, along with strong assessment pairs and supporting tools (e.g., RSI and MACD).  

In summary, again, ADX does not predict direction; it measures conviction to direction. If you learn to use and apply ADX, you will have the clarity, confidence, direction, and precision to trade successfully.