The Aroon indicator measures how long it's been since price made a new high or low over a lookback period, expressed as two lines from 0 to 100: Aroon Up (based on the most recent high) and Aroon Down (the most recent low). Its distinctive job is flagging trend onset — when a new trend is starting.

Reading the lines

Aroon Up near 100 means price made a new high very recently — strong upward momentum. Aroon Down near 100 means a recent new low — strong downward momentum. When Aroon Up crosses above Aroon Down, a potential uptrend is beginning (and vice versa). When both lines are low, price hasn't made new highs or lows lately — a range/consolidation.

How to use it

Use Aroon to time the shift from range to trend. Both lines low = consolidation (favor reversion or stand aside); an Aroon crossover with one line pushing to 100 flags a chop-to-trend transition beginning — a cue to switch to trend-following. It complements ADX: ADX measures trend strength, Aroon flags trend onset.

Aroon's edge is timing the birth of a trend — the crossover as one line spikes to 100 while the other collapses is a range breaking into a move.

The limits

Aroon lags and whipsaws in choppy tape (frequent crossovers with both lines mid-range), so it's a context filter, not a precise trigger. It's most useful combined with price structure and the regime — an Aroon crossover confirmed by a break of structure and a supportive regime is a real trend-onset read. Use it to sense the shift, then trade the levels.