ADX (Average Directional Index)
The Average Directional Index, or ADX, measures the strength of a trend regardless of its direction. Developed by J. Welles Wilder, ADX is a non-directional indicator that ranges from 0 to 100. A low ADX tells you the market is choppy; a rising ADX confirms a strengthening trend. Indian traders use ADX to filter out range-bound noise and pick the right time to deploy trend-following strategies.
Key takeaways:
- ADX measures trend strength on a scale of 0 to 100. It does not say if the trend is up or down.
- Typical thresholds: ADX below 20 = weak trend; 20–25 = developing; above 25 = strong trend.
- ADX comes with +DI and −DI lines that indicate trend direction.
- Best paired with trend-following strategies — buy dips in uptrends with high ADX.
- Default period is 14, but Indian intraday traders often shorten it to 10.
Anatomy of ADX
The ADX system has three lines: +DI (positive directional indicator), −DI (negative directional indicator) and ADX itself. +DI captures upward price pressure; −DI captures downward pressure. ADX is a smoothed measure of the spread between +DI and −DI, expressed as a single number.
Reading ADX values
| ADX value | Implication |
|---|---|
| Below 20 | Choppy or sideways market; avoid trend strategies |
| 20–25 | Trend forming; watch for continuation |
| 25–50 | Strong trend; trend-following ideal |
| Above 50 | Very strong; potential for extreme moves |
+DI and −DI crossovers
The classic Wilder signal: when +DI crosses above −DI, the trend is turning bullish; when −DI crosses above +DI, bearish. Combine with ADX > 20 to filter out false signals in sideways markets. Many traders only act on crossovers when ADX is rising — confirming that the trend is gaining strength.
Worked example on Nifty
Suppose Nifty is consolidating between 21,800 and 22,200 with ADX at 15. The signal is clear — wait. When the index breaks above 22,200 and ADX rises through 25 with +DI above −DI, the breakout is more likely to sustain. Conversely, an ADX above 35 that starts to flatten can indicate trend exhaustion.
Limitations to remember
- ADX is lagging — it confirms trends after they begin.
- High ADX does not predict reversal; it only indicates current strength.
- In choppy markets, +DI/−DI cross frequently, producing whipsaws if ADX is ignored.
- Default 14-period can be slow for intraday; shorten thoughtfully.
How to combine ADX with other tools
- Moving averages: Use ADX to validate breakouts above key MAs.
- Price action: Trade only the strong trends — ADX > 25 with clean structure.
- RSI: ADX trends + RSI pullbacks form classic continuation trades.
- Volume: Rising volume + rising ADX = confirmation of trend strength.
Frequently asked questions
Does ADX tell me the direction of the trend?
No. Direction comes from +DI vs −DI; ADX only measures strength.
Can ADX be used on Bank Nifty?
Yes, with the same defaults. Bank Nifty often has cleaner ADX trends than smaller stocks.
Why does my ADX read low even though prices look trending?
ADX considers the recent range; small but persistent moves may not register as strong trends. Try a shorter period to be more responsive.
Is ADX useful for delivery investing?
Indirectly. ADX on weekly or monthly charts can hint at major regime changes in indices and sectors.
