What is Aroon?
Aroon draws two lines between 0 and 100 in their own pane. Aroon Up is 100 when the current bar made the highest high of the window and falls step by step for every bar since that high. Aroon Down does the same for the lowest low. The window covers the current bar and the 14 before it.
Aroon measures time, not distance. It shows whether the latest high or the latest low is more recent, which is a way of describing a trend or the lack of one. It does not say how far price moved or how strong the move was, and it does not predict a breakout.
How to use Aroon
- Aroon Up near 100. Price has made a new high for the window recently. Repeated readings at or near 100 mean new highs keep coming.
- Aroon Down near 100. Price has made a new low for the window recently.
- Crosses. Aroon Up crossing above Aroon Down means the most recent high is now fresher than the most recent low, and the reverse. The cross is often used as a sign that the dominant direction has changed.
- Both lines low. When neither line is high, the window's extremes are both old, which usually means price is consolidating inside them.
These are ways to read the lines, not entry signals on their own.
Settings
| Setting | Default | What it changes |
|---|---|---|
| length | 14 | How many bars back the window reaches, in addition to the current bar. Lower makes the lines jump more often; higher looks over a longer stretch and changes less often. Minimum 1. |
Adjust the length in the indicator settings.
Calculation
Over a window of length + 1 bars, each line converts the number of bars since the extreme into a percentage:
Aroon Up = 100 * (14 - bars since highest high) / 14
Aroon Down = 100 * (14 - bars since lowest low) / 14With the default length of 14 the window is 15 bars, the current bar plus the 14 before it. A high on the current bar gives Aroon Up 100; a high on the oldest bar in the window gives 0. Each bar that passes without a new high lowers Aroon Up by 100 / 14, about 7.1.
Both lines therefore move in fixed steps rather than smoothly, and jump straight to 100 when a new extreme is made. No reference levels are drawn.
Limitations
- It ignores distance. A new high by a single tick counts the same as a large breakout.
- It moves in steps. The lines change by fixed amounts and can jump from low to 100 in one bar, which makes them look more decisive than the underlying move.
- Crosses whipsaw in ranges. In a tight range, highs and lows alternate and the lines cross often without a trend following.
- Old extremes drop out abruptly. When the bar holding the high leaves the window, a new, lower high becomes the reference and the line jumps.
- The live candle moves. The current bar can set a new high or low and then give it back before it closes, so the latest values can change.
Frequently asked questions
Aroon is a pair of lines, Aroon Up and Aroon Down, that measure how many bars have passed since the highest high and the lowest low of a window, expressed from 0 to 100. A value of 100 means the extreme was made on the current bar.
Aroon Up staying high while Aroon Down stays low describes an uptrend, with new highs being made and the lows far behind. The opposite describes a downtrend. Both lines low means price has not made a fresh extreme in a while, often a range. Crosses mark a change in which extreme is more recent.
Yes. The indicator declares one input, length, default 14 with a minimum of 1. The window covers that many bars plus the current one. Open the indicator's settings on the chart to change it.
It counts bars, not prices. Each bar without a new extreme lowers the line by a fixed step, and a new extreme sends it straight back to 100. That is how the indicator is defined, not a display problem.
No. Closed bars are not revised. The current bar's values move while that bar is live, because a new high or low made during the bar can still be undone before it closes.
Use the Add to chart button at the top of this page. It opens BTC/USDT on Binance in the Altrady Charts terminal with the built-in Aroon already applied. On any other market, open the indicator picker on the chart and choose Aroon from the Trend group.