StockSignal
ADX 14 measures trend strength on a 0-100 scale using 14 periods. It does not indicate direction, only how strong the current trend is.
The Average Directional Index (ADX) measures trend strength on a scale from 0 to 100, without indicating trend direction. Developed by J. Welles Wilder Jr., ADX helps traders determine whether a market is trending strongly enough to trade using trend-following strategies, or if it's ranging and better suited for mean-reversion approaches.
The calculation components:
+DM = Current High - Previous High (if positive and > -DM) -DM = Previous Low - Current Low (if positive and > +DM) +DI = Smoothed +DM / ATR × 100 -DI = Smoothed -DM / ATR × 100 DX = |+DI - -DI| / (+DI + -DI) × 100 ADX = 14-period smoothed average of DX
Interpreting ADX levels:
- ADX 0-20: Weak or no trend; market is ranging
- ADX 20-25: Emerging trend; trend may be developing
- ADX 25-50: Strong trend; trend-following strategies work
- ADX 50-75: Very strong trend; powerful directional movement
- ADX > 75: Extremely strong; rare and may indicate exhaustion
Why ADX matters:
- Strategy selection: Determines whether to use trend or range strategies
- Trade filtering: Avoid trend trades when ADX is low
- Trend confirmation: Rising ADX confirms trend strength
- Exhaustion warning: Very high ADX may precede reversal
Using ADX with directional indicators:
- +DI above -DI: Bullish trend direction
- -DI above +DI: Bearish trend direction
- ADX rising with +DI above: Strong uptrend
- ADX rising with -DI above: Strong downtrend
Trading applications:
- Trend entry: Enter when ADX rises above 25 with directional alignment
- Trend exit: Consider exit when ADX starts declining
- Range trading: Use oscillators when ADX below 20
- Breakout confirmation: Rising ADX confirms breakout validity
ADX characteristics:
- Non-directional: Only shows strength, not whether bullish or bearish
- Lagging: Takes time to reflect trend changes
- Rising = strengthening: Regardless of current level
- Falling = weakening: Trend losing momentum
Limitations:
- Late signals: ADX confirms trends after they start
- No direction: Must use +DI/-DI for direction
- Prolonged readings: Can stay low or high for extended periods
ADX is essential for knowing when to use trend-following strategies. Without trend strength confirmation, traders may apply trending techniques to ranging markets, generating losses from whipsaws.