ADX (Average Directional Index) is a trend-strength indicator that measures how strongly price is trending on a scale from 0 to 100, regardless of direction, with readings above 25 generally indicating strong trends.
The ADX Scale
ADX oscillates between 0 and 100:
- ADX < 20: Weak trend or range-bound market. Price is choppy, lacking direction.
- ADX 20–25: Moderate trend. Price is moving but not decisively.
- ADX 25–40: Strong trend. Price is trending decisively. Good for trend-following.
- ADX > 40: Very strong trend. Often seen in volatile rallies or crashes. Trending aggressively.
Key point: ADX measures strength, not direction. ADX 40 tells you price is trending strongly up or strongly down, but not which.
ADX with DMI
ADX pairs with DMI (Directional Movement Index), which shows direction:
- +DI (Plus Directional Indicator): Strength of uptrends. Rising +DI shows uptrend power.
- -DI (Minus Directional Indicator): Strength of downtrends. Rising -DI shows downtrend power.
Together: ADX shows strength, +DI/–DI shows direction.
Example: ADX 35, +DI 30, -DI 15. Strong uptrend (ADX 35 = strong, +DI 30 > -DI 15 = up direction).
| ADX Level | +DI > -DI | -DI > +DI |
|---|---|---|
| < 20 | Weak uptrend | Weak downtrend |
| 20–30 | Moderate uptrend | Moderate downtrend |
| 30–40 | Strong uptrend | Strong downtrend |
| > 40 | Very strong uptrend | Very strong downtrend |
Using ADX to Filter Trades
Many trend-following strategies only trade when ADX is above a threshold, typically 25 or 30.
Logic: If ADX < 20, the market is chopping. Trend-following strategies lose money in chop. Waiting for ADX > 25 filters out low-probability trades.
Example: Your strategy buys golden crosses. But a golden cross in ADX 15 market (choppy) has low win rate. A golden cross in ADX 35 market (strong uptrend) has high win rate. So you only take golden crosses when ADX > 25.
This simple filter often improves win rate dramatically.
ADX Divergence: Trend Weakening
When ADX starts declining, even while still above 25, it signals the trend is losing strength. This is a warning sign.
Example: EUR/USD rallies with ADX 45 (very strong uptrend). Then ADX starts falling to 40, then 35. Price is still rising, but the uptrend is losing conviction. This often precedes consolidation or reversal.
Many traders use falling ADX as a signal to tighten stops or reduce size, even if price is still moving higher.
| ADX Level | Trend Status | Trade Action |
|---|---|---|
| Rising, > 25 | Strong and strengthening | Hold/add |
| Falling, > 25 | Strong but weakening | Tighten stops |
| Rising, < 20 | Weak and staying weak | Avoid |
| Falling, < 20 | Weakening further | Stay out |
ADX Limitations
ADX is lagging. By the time ADX reaches 40, a significant portion of the trend has already happened. You’re buying the move late.
Additionally, ADX doesn’t work well in ranging markets. In a choppy 50-pip range, ADX bounces between 10 and 20 constantly. It’s not useful there.
ADX is best used as a confirmation tool, not a primary signal. “ADX above 25” is a filter, not a buy signal.
Real Example
GBP/USD daily chart:
- January: Price rallies 200 pips. ADX rises from 15 to 35. Strong uptrend confirmed.
- February: Price continues but ADX starts declining from 35 to 28. Uptrend weakening.
- March: ADX drops to 18. Price chops sideways in a 80-pip range. Weak, choppy action.
- April: ADX rises to 30 on the back of a sharp sell-off. Strong downtrend starting.
Notice: ADX clearly separated trending from choppy phases. Traders would have profited more trading during January (ADX rising) and April (ADX rising) than February-March (ADX falling/low).
Trading Rules with ADX
- Use ADX as a filter: Only trade trend-following strategies when ADX > 25
- Avoid taking new entries when ADX is declining sharply, even if it’s still > 25
- Combine ADX with Parabolic SAR or moving averages to identify entry points
- In ADX < 20 markets, use range-trading or mean-reversion strategies instead
- Don’t over-weight ADX alone—it’s a confirmation, not a primary signal
PipJournal tracks your trades alongside ADX levels, showing whether your entries during ADX > 25 periods truly had higher win rates than ADX < 20 periods. You’ll measure if filtering by ADX actually improved your trading edge or if your strategy works regardless of trend strength.
