ADX: Trend Strength Without Direction, and With a Big Lag

ADX (Average Directional Index) measures trend strength on a 0–100 scale, regardless of direction. The +DI and −DI lines show which side dominates. A high ADX means a strong trend, but it often appears when the trend is already well advanced.

What it is

Another Wilder indicator. First the directional movements (+DM and −DM) are calculated, then their smoothed versions (+DI and −DI), and finally ADX as the smoothed difference between them. Every layer of smoothing adds lag.

The popular interpretation: ADX above 25 means a trend, below 20 no trend.

How people use it

as a filter: trade trend strategies only when ADX is high
+DI and −DI crossovers as direction signals
identifying consolidation when ADX is low

What the research and evidence say

ADX is used mainly as a filter in trend-following systems. As a standalone signal it has the same problems as other average-based indicators: lag and sensitivity to parameters. Independent research showing a lasting edge is hard to find.

Weaknesses

double smoothing creates a big lag
a high ADX often appears near the end of a move
the 20 and 25 thresholds are arbitrary
it doesn't tell you whether the trend is “healthy”, i.e. driven by real demand or supply

What order flow shows

Intraday trend strength shows better in how the market builds value: whether the value area keeps shifting in one direction, whether pullbacks are shallow and bought aggressively, whether delta confirms the move. That's real-time information, not something smoothed over a dozen periods.

Indicators vs order flow

Every indicator and every pattern in this section is built from the same data: a candle's open, high, low, close and sometimes volume. They're derivatives of price, showing the effect rather than the cause. Order flow looks at what price is made of: who was buying and selling aggressively (delta), where limit orders were waiting (the order book) and at which prices the market accepted trade (the volume profile).

On CME futures this data is real and comes from one central market. Spot forex doesn't have it: platforms show tick volume, the number of price changes at a single provider.

To be fair: order flow isn't the Holy Grail. It takes learning, it can be noisy, big players hide some of their orders, and an edge only comes from a process and risk control. But it gives you information that simply isn't on a candlestick chart.

How to use it sensibly

treat ADX as a description of whether there's been a trend recently
don't join a trend just because ADX crossed a threshold
check whether the market is moving value, not just price

Glossary: Day types
Atlas of biases: Hindsight bias
Order flow: The Initial Balance and day types: what the first hour says about the whole session
Order flow: Volume profile: how to read the POC, value area, HVNs and LVNs
Also under the microscope: RSI
Also under the microscope: MACD
Also under the microscope: The stochastic oscillator and Stochastic RSI

Frequently asked questions

What does ADX above 25 mean?

That one side clearly dominated in recent periods. It doesn't say which one, or whether the trend will continue.

Does ADX show the direction of the trend?

ADX itself doesn't. The +DI and −DI lines show direction.

Educational content, not investment advice. No signals, entries, stops or position sizes.