Aroon

Measures how recently price hit its highest high and lowest low to help describe whether a trend is present or absent.

What it is

Aroon is a trend indicator developed by Tushar Chande in 1995. It uses two lines, Aroon Up and Aroon Down, that each move between 0 and 100. Instead of measuring price or momentum directly, Aroon measures time: how many bars have passed since the most recent highest high (Aroon Up) and the most recent lowest low (Aroon Down) over a chosen lookback period. The idea is that in a strong uptrend, new highs happen often, so Aroon Up tends to stay high; in a strong downtrend, new lows happen often, so Aroon Down tends to stay high. The name comes from a Sanskrit word often translated as "dawn's early light." Nothing about Aroon is predictive; it describes what price has already done, and trading always carries risk of loss.

How it works

For a lookback period of N bars, Aroon Up = 100 × (N − number of bars since the highest high) / N, and Aroon Down = 100 × (N − number of bars since the lowest low) / N. If the highest high in the window is the current bar, "bars since" is 0 and Aroon Up = 100. If the highest high was N bars ago, Aroon Up = 0. Aroon Down works the same way using the lowest low. Both lines therefore sit between 0 and 100. A common default period is 25, though some platforms default to 14. A shorter period makes the lines react faster and flip more often; a longer period smooths them and reduces flips. Many platforms also plot an "Aroon Oscillator," which is simply Aroon Up minus Aroon Down, ranging from −100 to +100.

How traders read it

• Traders often read Aroon Up near 100 with Aroon Down near 0 as a sign that recent highs dominate the window (an up-leaning condition), and the reverse as a down-leaning condition.
• Crossovers of the two lines are commonly watched as the moment the balance of recent highs and lows shifts, rather than as a trade trigger in themselves.
• Both lines low and tangled together (often below 50) is frequently interpreted as no clear trend, since neither new highs nor new lows are occurring recently.
• Readings above 70 on one line are often treated as a stronger version of that line's reading, while neither line being near 100 is sometimes read as a move that is aging.
• The Aroon Oscillator (Up minus Down) crossing zero conveys the same line-crossover information in a single line.
• None of these readings predict the next move; they describe extremes that have already formed, and no indicator removes the risk of loss.

Common settings

A common default lookback period is 25, though some platforms use 14. Shorter periods such as 14 react faster but flip more often; longer periods such as 50 smooth the lines and reduce crossovers. The 70 and 30 levels are common reference lines (30 mirrors 70 for the opposite line), and 50 is often drawn as a midline.

Strengths

• Isolates the timing of recent highs and lows, which is information most price and momentum oscillators do not show directly.
• The fixed 0–100 scale makes readings easy to compare across instruments and timeframes.
• Can help describe whether a market is trending or directionless, which some traders use alongside other tools for context.

Pitfalls to watch

• Aroon is descriptive, not predictive. A line at 100 only confirms a recent high or low already happened; it does not forecast the next move and is not a recommendation to trade.
• In ranging or choppy markets the lines cross frequently, producing many crossovers that are hard to interpret. Aroon tends to be most informative when a market is actually trending.
• A reading can stay pinned at 100 long after momentum fades, because a single distant high or low keeps resetting the count. High Aroon does not mean strong price movement.
• Results depend heavily on the period setting; the same chart can look trending or trendless depending on whether you use 14, 25, or 50.
• Aroon is built from past extremes, so crossovers and resets often appear after a move is already underway. No single indicator removes the risk of loss, and nothing here is advice to buy or sell.

Pine v6 example

//@version=6
indicator("Aroon", overlay=false)

length = input.int(25, "Length", minval=1)

upper = 100 * (ta.highestbars(high, length + 1) + length) / length
lower = 100 * (ta.lowestbars(low, length + 1) + length) / length

plot(upper, "Aroon Up", color=color.orange)
plot(lower, "Aroon Down", color=color.blue)
hline(70, "Upper", color=color.gray, linestyle=hline.style_dotted)
hline(50, "Midline", color=color.gray, linestyle=hline.style_dotted)
hline(30, "Lower", color=color.gray, linestyle=hline.style_dotted)

Pro tip: Because Aroon can sit at 100 long after a move stalls, many traders pair it with a separate measure of price movement or volatility for context, rather than reading a high Aroon value as strength on its own. This is educational context, not a recommendation to trade.

Educational only — not financial advice, not a recommendation to trade. No indicator is predictive; trading involves substantial risk of loss.