Average Directional Movement Index
ADX does not care about direction — only trend strength: higher readings mean a stronger trend, lower readings mean chop. It is the referee that decides whether to use trend tools or range tools.
What it is
The Average Directional Movement Index (ADX), introduced by J. Welles Wilder in 1978 in the same book as RSI, measures the strength of directional movement — not its direction. +DI and −DI gauge upward and downward movement separately; ADX smooths the strength of their separation into a 0–100 value. Rising ADX means the current trend (up or down) is strengthening; falling ADX means the trend is fading or the market is ranging.
Origin
ADX and the DMI (Directional Movement Index) system come from Wilder's 1978 "New Concepts in Technical Trading Systems" — one of the book's four inventions alongside RSI, ATR and Parabolic SAR. Originally built for daily commodity futures, it is now the global standard for the "trend or range?" question — nearly every trend-following system checks ADX first.
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The DMI computation chain (simplified):
The whole chain sits on Wilder smoothing (same as RSI/ATR), so ADX reacts calmly to single-bar spikes. MT5's default period is 14. ADX does not distinguish up from down — direction comes from the relative position of +DI and −DI; strength comes from ADX. Read them together.
Worked example
A side-by-side comparison:
- Market A: price rallies one-way for 10 days, closing near highs every day — +DI towers over −DI, ADX climbs past 40: a strong trend, heaven for trend-following.
- Market B: price bounces inside a 5% box for two months — +DI and −DI tangle, ADX sags below 15: textbook range, where MAs and trend tools all fail.
- Market C: ADX climbs from 18 through 25 while +DI crosses above −DI — the classic birth of a new trend out of a range.
ADX's value is not prediction but toolbox selection: high ADX → trend strategies (MA/MACD with the trend); low ADX → reversion strategies (Bollinger/RSI extremes). Ask ADX first, then choose your weapon.
How to read it
ADX ranges and common interpretations:
| Range | Common interpretation |
|---|---|
| 0 – 20 | No/weak trend: MAs knot, breakouts fail — the territory of range strategies |
| 20 – 25 | The threshold zone: a trend is brewing; watch which DI dominates |
| 25 – 40 | Trend confirmed: the comfort zone for trend-following |
| 40 – 60 | Strong trend: do not fade it lightly; a rollover from up here hints at fading momentum |
| 60+ | Extreme (historically rare): panic or mania phases — have an end-of-trend plan ready |
Two common mistakes: (1) high ADX does not mean "will rise" — direction is the +DI/−DI question; (2) ADX rolling over from 50 does not mean the trend instantly ends — momentum is decelerating, the trend may continue, but the odds of fading it start improving.
Common signals & usage
ADX crossing above 25 (trend confirmed)
A climb out of the range zone through 25, with a DI direction — the trend-confirmed signal where trend strategies switch on.
+DI / −DI cross
+DI crossing above −DI = bullish dominance, below = bearish. Crosses at ADX > 25 are worth far more than those at ADX < 20.
ADX rollover from highs
The first pullback of ADX from a 40+ peak — decelerating momentum, often near the end of the sprint: a trim cue, not a reversal signal.
First climb after a long low
ADX surging after months below 20 — the coil is breaking and a new trend is being born; enter with the breakout direction.
Limitations & common mistakes
- ADX gives no direction: trading on ADX alone is a coin flip — direction always comes from +DI/−DI or price structure.
- Lag from smoothing: 14-period Wilder smoothing means ADX reaches 25 only a third of the way into a trend — accept missing the fish head.
- The 20–25 gray zone: when ADX hovers there, neither strategy works well — staying flat is also a strategy.
- Do not confuse it with RSI: high RSI = overbought (a directional extreme); high ADX = strong trend (direction unknown). Completely different semantics.
- Lower-timeframe noise: 15-minute ADX jitters badly — widen the threshold to 30 or lengthen the period.
ADX in MT5
ADX is a built-in MT5 trend indicator (draws ADX, +DI and −DI). The MQL5 function for programmatic use is iADX:
| MQL5 function | iADX() |
| Default period | adx_period=14 |
| Buffers | 0=main ADX line, 1=+DI (PLUSDI_LINE), 2=−DI (MINUSDI_LINE) |
| Variant | iADXWilder() (strict Wilder-original smoothing) |
| Display window | Sub-window (no fixed OB/OS levels) |
MT5 ships two versions: iADX (convention matching most platforms) and iADXWilder (strictly Wilder's original smoothing). Values differ slightly — check which version an external analysis used. Buffers 0/1/2 map to ADX/+DI/−DI respectively.
Behavior across timeframes
15-minute
Noisy: widen the threshold to 30 or use a 20-period setting; mainly for filtering false breakouts
1-hour / 4-hour
The swing-trader's regime switch: ADX > 25 turns trend strategies on, < 20 switches to reversion
Daily
Wilder's native habitat: the 25/40 thresholds are most classic here and trend confirmations carry the most weight
Weekly
Weekly ADX > 30 marks the true long-term trend instruments — a powerful filter for building a long-term watchlist
Indicator combinations
ADX is almost always the supporting actor. Common pairings:
- With MACD: trust MACD crosses only when ADX > 25 — a trend filter that deletes most range-market false signals. MACD
- With Bollinger Bands: an ADX < 20 squeeze deserves attention (ranges breed breakouts); an ADX > 25 squeeze deserves less. BOLL
- With RSI: when ADX is high (trend), use RSI pullbacks for entries; when low (range), use RSI extremes for reversion. RSI
Symbols commonly watched with ADX
Symbol pages that list this indicator as a common tool:
FAQ
Q What ADX level counts as a strong trend?
Rule-of-thumb thresholds: below 20 no trend, above 25 trend confirmed, above 40 strong (Wilder himself flagged 40 as "a very strong trend"). These come from daily commodity-futures history — tune per instrument and timeframe. The direction of change (rising/falling) matters more than the absolute value.
Q How is ADX different from RSI?
Different dimensions entirely: RSI measures relative up/down momentum and flags overbought/oversold (directional extremes); ADX measures trend strength with no regard to direction — ADX 80 can be a crash or a melt-up. ADX answers "which toolbox", RSI answers "is momentum extreme".
Q How do +DI and −DI work?
+DI measures upward movement, −DI downward: +DI on top = bulls lead, below = bears lead. The cross is a direction-change signal — but only worth trusting when ADX > 25; when ADX is low the two lines tangle with no information.
Q What is the difference between MT5's iADX and iADXWilder?
The smoothing differs: iADX follows the convention used by most platforms, iADXWilder follows Wilder's 1978 book exactly. Values differ slightly — confirm the version before comparing against external material or other platforms.
Q How do I add ADX in MT5?
Menu: Insert → Indicators → Trend → Average Directional Movement Index, or drag it from the Navigator onto a sub-window. Default period 14; the chart shows the ADX main line plus the +DI/−DI auxiliary lines — a main-line cross above 25 is the common trend-start read.
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