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 and says 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 and 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. Below 20 the stock is drifting and trend-following tools like moving average crosses, Supertrend flips and 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, so 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. It also 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 already in progress.
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. ADX measures how much directional ground is being covered, and it 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 25 Sept 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 Supertrend flipping from down to up, with ADX over 20 behind it.
Parabolic SAR flips bullish
Price crossing above the parabolic SAR with ADX over 20.
DI bullish cross
+DI overtaking −DI while ADX confirms there is a trend worth joining.
DI bearish cross
−DI overtaking +DI with ADX above 15.
Ten sessions above the 20-day
Ten straight closes above the 20-day average with ADX over 25. Two weeks without a wobble.
Strong directional trend
ADX above 30, +DI over −DI, the averages stacked, RSI still under 70.
Above the 20-day most of the month
Closed above the 20-day average on 17 of the last 20 sessions, ADX over 20. The forgiving version of a persistence scan.
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. ADX is direction-agnostic, so 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 fire constantly in sideways markets, where nearly all of them fail. DI crosses, Supertrend flips and average crossovers all behave this way. Requiring ADX above 20 confines the signal to stocks where a trend exists to change, and its effect on any scan's hit rate is directly testable here.