Most trend indicators measure price — how far it moved, how fast, how steep the angle. The Aroon indicator measures something different: time. Developed by Tushar Chande, Aroon (from the Sanskrit word for "dawn," meant to evoke the start of a new trend) tracks how many bars have passed since the highest high and the lowest low of a look-back period, then converts that elapsed time into two bounded 0-100 lines — Aroon Up and Aroon Down. A fresh high just this bar pushes Aroon Up to 100; a high that hasn't been challenged in a long time lets Aroon Up decay toward 0. That's the entire idea, and it makes Aroon one of the few widely used indicators that reads trend freshness rather than trend size.
How Aroon Is Calculated
For a chosen period (default 14), Aroon looks back over the last Period bars plus the current one and finds two things: how many bars ago the highest high occurred, and how many bars ago the lowest low occurred. Those two counts are converted to a 0-100 scale with a simple formula:
- Aroon Up =
((Period − bars since the highest high) / Period) × 100 - Aroon Down =
((Period − bars since the lowest low) / Period) × 100
If the highest high in the look-back window happened on the current bar, "bars since" is 0, and Aroon Up reads exactly 100 — as fresh as a new high can be. If the highest high happened Period bars ago (the oldest bar still inside the window), Aroon Up reads 0 — about to roll out of the look-back entirely. Aroon Down works identically off the lowest low. Neither line looks at how far price moved to make that high or low, only at how recently it happened — which is why two markets with wildly different volatility can still produce comparable Aroon readings, something ATR or Standard Deviation can't do, since both scale directly with price movement. There's no built-in Aroon function in either MetaTrader 4 or MetaTrader 5, so aroon-alert.mq4/.mq5 calculate both lines directly from the High and Low arrays rather than wrapping a platform indicator call.
Entry Conditions
The signal is a direct crossover between the two lines. When Aroon Up crosses above Aroon Down, a new high has become more recent than any recent low — read as the early stage of a fresh uptrend. When Aroon Down crosses above Aroon Up, the mirrored condition applies to the downside. The alert logic in aroon-alert.mq4/.mq5 checks the two most recently closed bars for exactly this cross. Because both lines are bounded at 0 and 100, where the crossing line sits matters: a cross that happens with the winning line already near 100 means the high or low behind it is genuinely fresh, while a cross that happens with both lines hovering in the middle of the range (around 40-60) is a much weaker signal — the "trend" it's flagging could just be sideways chop where highs and lows keep trading places every few bars.
Aroon vs ADX and Parabolic SAR
Aroon sits alongside ADX and Parabolic SAR as a trio of trend-direction tools, but each one answers a different question. ADX's +DI and -DI lines measure the magnitude of directional price movement, smoothed with Wilder's method — they answer "how much has price moved in each direction, and how strongly." Parabolic SAR tracks an accelerating stop-and-reverse point glued to price itself — it answers "where would a trailing stop sit right now." Aroon ignores magnitude entirely and answers a third, narrower question: "how long ago did the market last make real progress in each direction." A market can grind sideways in a tight range for weeks and still produce large ADX readings if the small moves inside that range are choppy enough, but Aroon Up and Aroon Down will both stay depressed near the middle of their scale the whole time, because neither a fresh high nor a fresh low is actually forming. That makes Aroon a genuinely different piece of information rather than a slower or faster version of the same idea — worth checking alongside ADX rather than instead of it.
Parameters
- AroonPeriod (default 14) — the look-back window both Aroon Up and Aroon Down are calculated over. A shorter period (7-10) reaches 100 faster on any new high or low and decays faster too, producing more frequent crossovers; a longer period (20-25) smooths both lines and reduces how often marginal, short-lived highs and lows trigger a cross.
- EnableAlert / EnablePush — toggle the on-screen popup alert and mobile push notification independently when a new Aroon Up / Aroon Down crossover occurs.
How Traders Combine Aroon with Other Tools
Because a fresh-high/fresh-low cross can happen even in a market that's really just chopping sideways, many traders treat Aroon as a filter or confirmation tool rather than a standalone signal. Checking Trend vs Range market structure before acting on an Aroon cross is a natural first filter — a crossover that lines up with the broader structure carries more weight than one fighting it. Aroon also pairs naturally with Donchian Channels, since both are built from the same underlying idea (the highest high and lowest low of a look-back period) but expose different information: Donchian plots where those levels actually sit as tradeable price bands, while Aroon tells you how recently they were set. Used together, a Donchian breakout confirmed by an Aroon Up reading pushing toward 100 is a stronger read than either tool alone — the price band has been broken, and it just happened, not several bars ago.
A Word of Caution
Aroon's blind spot is the one built into its own design: it only counts when a high or low happened, never how far price traveled to get there. A market inching to a marginal new high by a single pip every few bars can hold Aroon Up near 100 indefinitely without any of the momentum a trader would normally associate with a strong trend. It's also prone to whipsaw in a genuinely range-bound market, where highs and lows keep swapping back and forth near the edges of the range and Aroon Up/Aroon Down cross repeatedly without either side ever gaining real control. As with any indicator built purely from historical highs and lows, a crossover confirms that a shift has already started — it cannot confirm in advance that the move will continue, and treating every cross as a standalone entry signal without a broader trend or structure filter is the most common way to misuse it.
Download the Indicator
This custom indicator plots Aroon Up and Aroon Down in a separate window and alerts on a crossover. Downloads for MetaTrader 4 and MetaTrader 5 are at the end of this lesson.