ADX (Average Directional Index)
ADX is Wilder's average directional index, a 0–100 gauge of how strongly a stock is trending in either direction — it measures the trend's strength while saying nothing about which way it points.
ADX starts from directional movement: how much of each session's range pushed above the previous high versus below the previous low. Those become the +DI and −DI lines, and ADX is the smoothed, absolute difference between them — high when one side consistently dominates, low when they trade the lead. The double smoothing, all Wilder's own, is why the 14-period version needs roughly twice that in history to settle, and why it turns deliberately.
The reading is a regime dial, not a signal. Below 20 the stock is drifting and trend-following tools — moving average crosses, Supertrend flips, breakouts — mostly produce noise; above 25 there is a trend worth joining, and above 40 a strong one. Its commonest use on daily NSE bars is therefore as the filter on other scans: a DI cross or a Supertrend flip with ADX above 20 is a change of control inside a market actually going somewhere.
Two honest caveats. ADX is direction-blind — a reading of 35 describes a powerful downtrend as readily as a powerful uptrend, and needs the DI lines or a price filter beside it to have an opinion. And it lags badly at turns: the double smoothing means ADX is still falling when a new trend starts and still elevated after one has died, so a rising ADX confirms a trend in progress rather than announcing a fresh one.
Against Aroon, the other trend-strength gauge here, the difference is the raw material: Aroon only asks how recently the highs and lows were made, while ADX measures how much directional ground is being covered — magnitude versus recency. ADX is the slower and sterner of the two.
In Sift
Written as adx(14). A working scan — stocks in a measurable trend with the moving averages stacked beneath price:
where adx(14) > 25 and close > sma(50) > sma(200)1
of the 500 most-traded NSE stocks match today, as of 20 Aug 2026
Scans that use it
Prebuilt scans in the library whose query reads this value — each with a hit-rate replay over the last 250 sessions.
Supertrend flips bullish
The ATR trailing stop turning up, with the trend strong enough to be worth trusting.
Parabolic SAR flips bullish
Price crossing above the parabolic stop, in a market with a trend to catch.
DI bullish cross
+DI overtaking −DI while ADX confirms there is a trend worth joining.
DI bearish cross
−DI taking control with directional movement building — the exit-or-avoid list.
Ten sessions above the 20-day
Price that has not closed below its 20-day average in two weeks. Persistence, not a single good day.
Strong directional trend
ADX above 30 with buyers in control and the averages stacked — a trend worth trading.
Common questions
What is a good ADX value?
The working conventions: below 20 means no meaningful trend, 25 and above means one worth trading, above 40 a strong one. But ADX is direction-agnostic — 40 can be a powerful decline. It answers whether the market is going somewhere, and needs the DI lines or price itself to answer where.
Does a falling ADX mean the trend is reversing?
No — it means directional movement is weakening, which is just as often a trend pausing to consolidate as one ending. A stock can digest a big advance sideways, let ADX bleed down, then resume. Reversal is a claim about direction, and ADX by construction holds no opinion on direction.
Why do so many scans pair signals with ADX above 20?
Because most trend-following signals — DI crosses, Supertrend flips, average crossovers — fire constantly in sideways markets, where nearly all of them fail. Requiring ADX above 20 confines the signal to stocks where a trend exists to change. It is the cheapest known filter against chop, and its effect on any scan's hit rate is directly testable here.