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Technical indicators
Aroon Indicator: Measuring Time Since the Last High and Low
The Aroon indicator is a technical measure developed by Tushar Chande in 1995. It counts the bars since the highest high and the lowest low in a window (25 bars in the StockCharts formulas) and scales each count from 0 to 100. Aroon Up and Aroon Down are the two lines, and their difference is the Aroon oscillator.
In brief
What is the Aroon indicator?
The Aroon indicator measures timing, not price distance. Here are the Aroon Up, Aroon Down and oscillator formulas, a worked example with assumed numbers, a table of readings, and the limits that apply.
Key takeaways
- The Aroon indicator counts how many periods have passed since the highest high and the lowest low of a window. It ignores how far price moved.
- With the default of 25 periods in the StockCharts formulas, each bar since an extreme lowers the reading by 4 points. TradingView's support article leaves the period to the trader and uses a 14-day window in its example.
- The Aroon oscillator is Aroon Up minus Aroon Down. It runs from -100 to +100, and a positive value means the most recent extreme in the window is a high.
- A reading of 100 means the extreme is on the latest bar. It describes past bars and does not forecast the next move.
- Check the period, the bar data and the oscillator setting on your own platform before you compare Aroon values with anyone else's chart.
What the Aroon indicator measures
The Aroon indicator was developed by Tushar Chande in 1995, according to the StockCharts ChartSchool Aroon entry. It does not average prices the way a moving average does. It counts how many bars have passed since the highest high and the lowest low inside a fixed window.
That makes Aroon a timing measure. A new high that is only slightly above the old one resets the count in the same way as a large breakout, because Aroon reads only how long ago the extreme occurred. For a measure of trend strength built on directional movement, see the ADX indicator. For a comparison of the close with a recent range, see the stochastic oscillator.
Aroon Up and Aroon Down formulas
The standard formulas use a window of N periods. Each line counts the bars since the extreme inside that window, one for the highest high and one for the lowest low. StockCharts describes N = 25 as its default parameter.
- Aroon Up = 100 x (N - periods since the N-period high) / N
- Aroon Down = 100 x (N - periods since the N-period low) / N
With N = 25, the formulas become Aroon Up = 100 x (25 - Days Since 25-day High) / 25 and Aroon Down = 100 x (25 - Days Since 25-day Low) / 25. StockCharts uses Days Since to mean bars since the extreme. A count of 0 means the high or low is on the latest bar, which gives 100. A count of 25 means the extreme is at the edge of the window, which gives 0.
Because 100 divided by 25 is 4, each bar since the extreme lowers the reading by 4 points at N = 25.
The Aroon oscillator
The Aroon oscillator subtracts Aroon Down from Aroon Up. The StockCharts ChartSchool Aroon Oscillator entry defines it as Aroon-Up minus Aroon-Down, with a range from -100 to +100 and zero as the midpoint. The same page gives 25 periods as the default.
A positive value means Aroon Up is higher, so the most recent extreme in the window is a high. A negative value means the most recent extreme is a low. Some platforms draw the oscillator in its own panel and some do not, so confirm the definition in your software before you compare values.
Aroon worked example: a 25-bar window
This is an Example with assumed numbers, not a chart of a real instrument. The window ends on the current bar, and the bar count starts at 0 on that bar. The diagram uses the same figures.
- 01
Find the high
Example: the highest high in the 25-bar window occurred 5 bars ago.
- 02
Calculate Aroon Up
Example: (25 - 5) / 25 x 100 = 80.
- 03
Find the low
Example: the lowest low occurred 18 bars ago.
- 04
Calculate Aroon Down
Example: (25 - 18) / 25 x 100 = 28.
- 05
Calculate the oscillator
Example: 80 - 28 = 52. The result is positive, so in this Example the most recent extreme is the high.
The result describes this window only. It does not say what the price will do next.
Table of Aroon readings at N = 25
The table applies the formula above to a range of bar counts, so you can check your own readings by hand.
| Bars since the extreme | Aroon value | How to read the value |
|---|---|---|
| 0 | 100 | The high or low is on the latest bar |
| 5 | 80 | Recent extreme, the same count as the worked example high |
| 12 | 52 | Still above the 50 centreline |
| 13 | 48 | Just below the 50 centreline |
| 18 | 28 | An older extreme, in the lower part of the scale |
| 25 | 0 | The extreme is at the edge of the window |
Calculated with the formula in this guide at N = 25. The right-hand column describes the scale and does not state what price will do next.
Default period and variant settings
References do not always agree on the period, so record the setting whenever you compare readings. The formulas in this guide use 25, the default that StockCharts gives. TradingView's support article leaves the period to the trader and uses a 14-day window in its example, and a different period changes every reading.
| Reference | Default period | What the reference states |
|---|---|---|
| StockCharts ChartSchool, Aroon | 25 | Formulas use 25 days, the default SharpCharts parameter, and attribute the indicator to Tushar Chande in 1995 |
| StockCharts ChartSchool, Aroon Oscillator | 25 | Oscillator is Aroon-Up minus Aroon-Down, with a default of 25 periods |
| TradingView support, Aroon | No default stated; 14 days in its example | Says the calculation relies on a user-defined period and attributes the indicator to Tushar Chande in 1995 |
Checked on 10 November 2026 against the three pages listed in this table.
The window also changes the scale. With N = 14, a high 5 bars ago gives Example: (14 - 5) / 14 x 100 = 64.3 under the same formula, compared with 80 at N = 25. Use the input your platform shows, and state which value you used whenever you describe a reading.
How educational sources describe the readings
StockCharts describes several reading zones. They are conventions for talking about the scale. They are not tests that a trade will work, and the sources do not give success rates for them.
- Centreline at 50. With N = 25, a value above 50 means the extreme occurred within the last 12 periods. A value below 50 means it occurred 13 or more periods ago.
- Consistently high readings. StockCharts says these mean prices are regularly hitting new highs or new lows for the specified period.
- Consistently low readings. StockCharts says these indicate that prices are seldom hitting new highs or lows.
- Both lines low (consolidation). StockCharts gives two thresholds for this picture. Its body text signals consolidation when both lines are below 50 and/or moving lower in parallel. Its Bottom Line says a consolidation is present when both lines remain below 30, or move lower in parallel. This guide does not choose between the two.
The StockCharts wording describes past bars only. Consistently high readings mean prices are regularly making new highs or lows, which is not a forecast, and the pattern can fail. Compare the reading with the price chart and with the window length before you draw any conclusion.
Limits of the Aroon indicator
- Price size is ignored. A small new high and a large breakout both reset the count to zero.
- The window sets the result. Changing N from 25 to 14 changes every reading, so two charts with the same indicator name can disagree.
- Sideways markets. In a range, the two lines can swing between high and low readings and produce many changes of direction. The readings alone do not separate a trend from noise.
- Lag. Each reading depends on past bars, so a turn in price is not reflected until enough bars have passed.
- Bar handling. Gaps, session breaks, missing bars and different chart time frames change the bar count. Check how your platform builds its bars before you compare values.
- No volume. Aroon uses only the high and low prices and the bar count. It says nothing about how much traded, so read volume separately; see volume in trading.
Check your settings before you read a value
Before you compare an Aroon reading with another chart, confirm four things: the period N, the price source used for highs and lows, whether the oscillator is shown, and the time frame. Write these settings beside any screenshot or note.
A single indicator reading is one input to a trade plan, not the plan itself. The risk-reward ratio and the position size calculator help you check the arithmetic of a trade before you take it.
Risk disclosure
- The Aroon indicator describes how many bars have passed since recent highs and lows. It does not forecast price, and a reading of 100 does not guarantee a continued move.
- Trading can lose money. Any position needs a plan for entry, exit and size, and the indicator is one input to that plan.
- Readings depend on the window length and the bar data. A different setting or data feed can change the values, so a value from one chart may not match another.
- Aroon can lag, and it can give many changes of direction in sideways markets. Do not use it as the sole basis for a decision.
- The examples use assumed bar counts. They are illustrations, not recommendations, and they do not describe any real instrument.
- This page is educational and is not personal financial advice.
RTX5 status
This guide explains the Aroon indicator in general and does not describe an RTX5 feature. No RTX5 release record confirms which indicators, chart types or alerts the product includes. Its Windows desktop client is in preview, and the web and mobile clients are planned. A Google Play listing for Android is published, but the mobile client has no approved release record yet; check the product-availability record before relying on any RTX5 feature.
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Primary references
Sources were checked on 10 November 2026. They explain market rules and concepts; they do not certify RTX5 or provide individual financial advice.
StockCharts ChartSchool: AroonGives Aroon-Up as ((25 - Days Since 25-day High)/25) x 100 and Aroon-Down likewise for the low. States that 25 is the default SharpCharts parameter, that a count above 50 means an extreme within the last 12 days, and that the indicator was developed by Tushar Chande in 1995. Checked 10 November 2026.StockCharts ChartSchool: Aroon OscillatorGives Aroon Oscillator = Aroon-Up minus Aroon-Down, with a range from -100 to +100, zero as the midpoint, and 25 periods as the default. Does not name an author. Checked 10 November 2026.TradingView support: AroonSays the Aroon indicator was developed in 1995 by Tushar Chande and that the calculation relies on a user-defined period. Uses a 14-day Aroon-Up and Aroon-Down in its example and states no default period. Checked 10 November 2026.RTX5 product availabilityInternal reference for the RTX5 status of the Windows desktop client, the web and mobile clients, and indicator features.
Questions readers ask
What is the Aroon indicator?
The Aroon indicator is a technical measure developed by Tushar Chande in 1995. It counts the bars since the highest high and the lowest low in a window (25 bars in the StockCharts formulas) and scales each count from 0 to 100. It describes the timing of recent extremes. It does not measure price distance or forecast direction.
How is Aroon Up calculated?
Aroon Up equals 100 times the number of periods minus the periods since the highest high, all divided by the number of periods. With N = 25, a high set on the latest bar gives 100, and a high 5 bars ago gives 80. Aroon Down applies the same formula to the lowest low in the window.
What is the Aroon oscillator?
The Aroon oscillator is Aroon Up minus Aroon Down. Its range is -100 to +100, with zero as the midpoint. A positive value means the most recent extreme in the window is a high, and a negative value means it is a low. It is a timing comparison, not a buy or sell rule.
What is the default Aroon period?
StockCharts uses 25 periods in its Aroon formulas and calls 25 its default parameter. TradingView's support article states no default and uses a 14-day window in its example. Check the input setting on your own platform before you compare values with another chart.
Does a reading of 100 mean the price will keep rising?
No. A reading of 100 means the highest high in the window occurred on the latest bar. It describes past bars and does not forecast direction. StockCharts describes consistently high readings as prices regularly hitting new highs or lows. That describes past bars, and the pattern can fail.
Does the Aroon indicator use volume?
No. Aroon uses the bar count since the highest high and the lowest low in a window. It does not use volume, so it says nothing about how many shares or contracts traded. Volume is a separate input, and you can read it alongside Aroon on your own chart.
Keep learning
ADX indicatorA trend measure built on directional movement, useful for comparing with Aroon's timing view.Stochastic oscillatorA momentum oscillator that compares a close with a recent range, which answers a different question from Aroon.What is MACD?A moving-average momentum indicator, for comparing how different indicators describe the same price history.Risk-reward ratioHow to compare the distance to a stop and a target before any trade.