What is the ADX?

Three lines, and only one of them is the ADX

• +DI measures how much of the recent movement was upward.
• -DI measures how much was downward.
• ADX measures how far apart those two are, smoothed. That distance is what "directional" means here.

So the direction lives in the two DI lines, and the ADX is only their separation. When +DI and -DI are close together, the market has been moving both ways in roughly equal measure and the ADX is low. When one dominates, the ADX rises, and it rises the same amount whichever one is dominating.

What the numbers conventionally mean

Below 20 is usually called no trend, above 25 a trend, above 40 a strong one. These are conventions rather than thresholds the market recognises, and the boundary matters less than the slope.

A rising ADX means the movement is becoming more one-sided than it was. A falling ADX means it is becoming less so, and that includes a trend that is still going but is now being met by pushes in the other direction.

The reading that catches people out is a falling ADX in a market that is still rising. It is not a contradiction: the market is still going up and it is doing so less exclusively than before. The indicator has described exactly that, and the reader supplied the word "reversal".

What it is genuinely good for

One job, and it does it better than anything else: telling you which of your rules applies. This is the same question the guide on market regimes asks, and the ADX is the closest thing to a numerical answer.

A low ADX says the market has not been directional, so rules built for a range have their best chance and rules built for a trend will misfire. A high ADX says the opposite. Used that way, as a switch between two sets of rules rather than as a signal, it earns its place.

It is also lagging by construction, because it is a smoothed average of smoothed differences. By the time it confirms a trend, the trend has been running. That is a limitation of what it measures, not a defect.

The mistakes that cost the most

Reading it as bullish or bearish. It has no direction. The DI lines have direction; the ADX has only strength.

Buying a rising ADX. A rising ADX in a downtrend means the fall is getting cleaner.

Waiting for 25 to act. By the time a smoothed average of differences crosses a threshold, most of the move that produced it is behind you.

Trading the DI crossings. They cross constantly in a quiet market, which is exactly when the ADX is telling you nothing is happening.

Questions people ask

Does a high ADX mean the price is going up?

No, and this is the whole point of the indicator. A high ADX means the recent movement has been one-sided. Which side it is on is shown by the two DI lines, not by the ADX.

What is a good ADX level?

Below 20 is conventionally no trend, above 25 a trend, above 40 a strong one. The slope is more informative than the level: rising means the movement is becoming more one-sided than it was, whichever way it is going.

What are the +DI and -DI lines?

They measure how much of the recent movement was upward and how much was downward. The ADX is a smoothed measure of the gap between them, which is why it carries strength without direction.

What are the best ADX settings?

Fourteen periods is the default and the one most traders are looking at. Shorter settings react sooner and cross the conventional thresholds more often; longer ones are calmer and later. Neither removes the lag, which is built into a smoothed average of smoothed values.

Reading strength alongside direction

Trading AI reads a photo or a screenshot of any chart and returns the indicator readings visible in the image, alongside the market regime, the structure, the key levels and a full trade plan with its risk. The analysis works from the image, so an indicator panel that is not on screen cannot be read.

The question the ADX is really answering: What is a market regime?

The direction the ADX deliberately leaves out: What is market structure?

The other reading that pins at its extreme while a trend lasts: What is the RSI?

This page is educational. It is not financial advice, and nothing here is a recommendation to buy or sell anything.