Short answer: the ADX indicator, short for average directional movement index, measures trend strength on a scale from 0 to 100 without telling you the direction. Readings under 20 mean no usable trend, readings above 25 mean a trend worth respecting, and readings above 50 mean a powerful one. Two companion lines, +DI and -DI, supply the direction. Together, the three lines tell you whether to trade with the trend, fade the range, or stand aside.
This page is for forex, index, metals and crypto CFD traders who see the ADX on their trading platforms and want a plain reading rule. By the end you should know what each line does, what the numbers mean, and how to fit the tool into trading decisions without over-trusting it.
What the three lines actually do
Most technical indicators draw one line. The ADX draws three, and the ambiguity around which line does what causes most of the confusion.
- +DI (plus directional indicator): how much of the recent movement came from new highs. It rises when price keeps pushing above the previous session's high.
- -DI (minus directional indicator): how much came from new lows. It rises when price keeps breaking the previous session's low.
- ADX: a smoothed measure of the gap between +DI and -DI. A wide gap means one side is winning decisively, so the ADX rises. A narrow gap means a lopsided battle has turned even, so the ADX falls.
The consequential point is that the ADX line has no sign. It climbs during a violent sell-off exactly as it climbs during a steady advance. Direction lives in the DI lines alone, so trend analysis with this tool always means reading them as a pair.
How the calculation works, step by step
You never need to compute this by hand, but the steps explain the lag.
- For each period, take the up move (current high minus previous high) and the down move (previous low minus current low). Keep only the larger, and only if it is positive.
- Divide that directional movement, smoothed over 14 periods, by the smoothed true range. This gives +DI and -DI as percentages.
- Take the difference between +DI and -DI, divide by their sum, and multiply by 100. That is the DX.
- Smooth the DX over another 14 periods. That is the ADX.
Two rounds of smoothing make the ADX sluggish by design. A fresh trend often runs six to ten sessions before the ADX crosses 25, so anyone expecting a punctual signal on the breakout candle will be disappointed.
Reading the values: a decision framework
The bands below are conventional and the edges are fuzzy, so treat them as zones rather than tripwires.
| ADX reading | Market condition | What a sensible trader does |
|---|---|---|
| Below 20 | No trend; price is choppy and disorderly | Range tactics only, or stay flat |
| 20 to 25 | A trend may be forming | Watch for a DI cross, size small |
| 25 to 50 | Established trend | Trade pullbacks in the DI direction |
| 50 to 75 | Very strong trend | Hold winners, trail stops, avoid fading |
| Above 75 | Extreme, rarely sustained | Expect the ADX to roll over soon |
The slope matters as much as the level. A rising ADX at 22 says a trend is building; a falling ADX at 35 says one is tiring. When the ADX turns down from a high reading, the trend has started to decelerate, not reverse, and price can drift the same way for weeks.
Market conditions also shape the numbers. Major forex pairs spend long stretches below 20, so a reading of 30 is noteworthy. Crypto CFDs like BTC and ETH cross 25 far more often, and 40 is ordinary, even unremarkable. Scroll back through your own instrument to see which bands it actually visits.
Trading strategies that use the ADX well
The ADX is a filter first and a trigger second. Three common approaches, from simplest to most demanding:
The trend filter. Only take trend entries when the ADX is above 25 and rising. This is a blunt rule, but it stops a lot of thankless counter-trend trades. It pairs naturally with any trend-following approach, where the ADX answers the question "is there a trend to follow at all?"
The DI crossover. Buy when +DI crosses above -DI, sell when -DI crosses above +DI, but only if the ADX is above 20. Below 20 the DI lines cross constantly and the market signals are threadbare.
The pullback entry. In an established trend with the ADX above 25, wait for a pullback toward a moving average while the DI lines stay in order. Set the stop with a volatility measure such as the ATR indicator rather than a fixed pip count, because trend strength and range size do not always agree.
Whatever you pick, the ADX says nothing about location. It will not tell you whether price is at support or in the middle of nowhere. That is why it seldom works alone and rarely appears by itself in any list of the best indicators for day trading.
Common mistakes and limitations
- Reading a rising ADX as bullish. It measures strength only. A rising ADX with -DI on top is a strong downtrend, and a crash prints the same high numbers as a grinding advance.
- Shorting because the ADX is "too high." A reading of 60 is not a reversal signal. It means the trend has been unforgiving to fighters, and fading it is a precarious trade.
- Entering on the DI cross in a range. Below 20 the DI lines are jittery. Each whipsaw carries a spread and commission cost, and those charges quietly squander a day's edge.
- Trusting a stale reading across a release. The ADX looks at the past 14 to 28 periods. A scheduled news number can flip the DI order in one candle.
- Optimising the lookback. Shortening 14 to 7 gives a skittish line with more crosses; lengthening to 20 gives fewer, later signals. Changing the setting after each loss is a fickle habit that never settles.
A worked example on a 10,000 account
Round numbers make the arithmetic plain. Start with a 10,000 account with a 1 percent risk rule, so 100 per trade. A major pair drifts sideways with the ADX at 15 for two weeks, and the DI lines cross four times. A trader taking every cross loses roughly 20 pips each, plus spread, for about 90 pips. On 0.2 lots that is close to 180, nearly two risk units gone on trades the filter would have skipped.
Then the pair breaks higher. +DI jumps above -DI, and the ADX climbs from 15 to 27 over eight sessions. Price pulls back 40 pips to the breakout level while +DI holds. Entry there, with a 50-pip stop below the pullback low, gives 0.2 lots at roughly 2 per pip, so 100 at risk. The ADX rises to 44 and stalls. A first target at two times risk is hit at plus 100 pips. The rest trails behind swing lows until -DI starts closing the gap, exiting at plus 130. Results vary, and one trade proves nothing, but the ADX kept this trader out of the ranging weeks and in the trending one.
The ADX under evaluation limits
A prop-firm evaluation changes how a trend filter earns its keep. DI crosses in a range arrive in clusters, and five small losses in a choppy session are exactly what a daily loss limit punishes. Pivex uses a daily loss limit that resets each day and a static, non-trailing total drawdown. Under those rules the honest use of the ADX is defensive. It gives you a reason to sit out low-reading sessions and save the daily budget for a clear trend.
There is also no time limit and no minimum number of trading days in the Pivex one-step evaluation. That removes the pressure to force entries when the ADX sits stubbornly below 20 for a week. Waiting costs nothing, while a clumsy fade in a dead market costs both pips and drawdown room.
Next step: pull up your main instrument and mark every session over the past three months where the ADX sat below 20. Count how many of your losing trades landed inside those windows; the answer is mostly humbling. Then decide on one threshold and one entry rule and write both down. Test them on a Pivex evaluation, where the built-in assistant tracks your daily limit for you.
Related guides: trend following and the ATR indicator.
Before participating, review Pivex's current program rules and decide whether a simulated proprietary trading evaluation fits your experience and risk limits. Participation does not guarantee a reward, income, or any particular trading result.