Introduction
The Average Directional Index (ADX) is a technical indicator used to measure the overall strength of a trendTrendThe general direction in which a security or market is moving over time.Read full glossary entry →. Developed by J. Welles Wilder in 1978 (who also developed RSI), the ADX is a non-directional indicator, meaning it rises whether price is trending strongly upwards or strongly downwards.
Why It Matters
- Avoids Whipsaws: Helps you avoid buying breakouts in non-trending markets, preventing unnecessary losses.
- Strategy Selection: Acts as a switch—telling you when to run trendTrendThe general direction in which a security or market is moving over time.Read full glossary entry →-following strategies versus mean-reversion range strategies.
- Identifies Exhaustion: Signals when an ongoing trend is running out of steam so you can protect your profits.
ADX Threshold Guide
| ADX Value | Market Phase | Recommended Action |
|---|---|---|
| Below 20 | Trendless / Sideways Range | Avoid trend strategies. Use range-bound oscillators (RSI bounds). |
| 20 to 25 | Developing Trend | Monitor for a potential breakoutBreakoutA price movement through an established support or resistance level. A breakout is often accompanied by increased volume, signaling strong momentum.Read full glossary entry →. |
| 25 to 40 | Strong Trending Market | Buy pullbacks. Run trend-following indicators (EMA crossovers). |
| Above 40 | Extreme / Overextended Trend | Lock in profits. Be cautious of immediate reversals. |
Directional Indicators (+DI and -DI)
ADX is mathematically derived from two other indicators developed by Wilder:
- Positive Directional Indicator (+DI): Measures upward price pressure.
- Negative Directional Indicator (-DI): Measures downward price pressure.
When +DI is above -DI, the trend is bullish. When -DI is above +DI, the trend is bearish. The ADX line itself aggregates the absolute difference between these two lines to show the net strength.
Common Beginner Mistakes
[!WARNING]
- Confusing Strength with Direction: Selling short because the ADX line is dropping. A falling ADX only means the trend is losing strength, not that the price is crashing.
- Buying Breakouts under ADX 20: Attempting to trade breakouts when ADX is flat below 20. These breakouts are highly susceptible to failing.
- Ignoring Trend Context: Buying an asset with a high ADX without checking if the price is trending up or down. Always verify direction using moving averages or +DI/-DI alignment.