--- title: "Average True Range (ATR): Formula" description: "Average True Range, introduced by J. Welles Wilder Jr., is a smoothed average of the true range, which is the largest of the current high-low range and the..." canonical: https://www.getswoopr.com/indicators/volatility/average-true-range/ source: "Swoopr Investment: https://www.getswoopr.com" --- ## Direct Answer > Average True Range (ATR) is a smoothed measure of true range that captures recent price volatility including gaps. A higher reading generally means the instrument has recently moved through larger ranges; a lower reading generally means recent ranges are smaller. The main limitation is that aTR measures magnitude, not direction; a high ATR can accompany either a rally or decline. # Average True Range (ATR): Formula, Meaning, Signals, Examples and How to Use It ## How Is Average True Range Calculated? Average True Range, introduced by J. Welles Wilder Jr., is a smoothed average of the true range, which is the largest of the current high-low range and the distances from the prior close to the current high and low. Including the prior close lets it capture gaps. **Formula:** `TR = max(High - Low, abs(High - prior Close), abs(Low - prior Close)); ATR = (prior ATR * (n - 1) + TR) / n` **Inputs:** - High, low and the prior close for each bar - Smoothing period n (14 periods is the usual default) - A starting ATR, typically the simple average of the first n true ranges **Worked example.** A bar with a high of 52 and a low of 49 after a prior close of 47 has a true range of 5.00, larger than its 3 point high-low range because of the gap. The inputs are illustrative numbers, not market data. **Reading it.** A higher ATR means recent bars have covered larger ranges, and a lower ATR means they have been smaller. It is expressed in the instrument's price units, so it is read against its own history or divided by price, not compared directly across instruments. **Limits.** ATR measures the size of movement, not its direction, so a high value can come with a rally or a decline. Because it is expressed in price units and smoothed, it lags sudden changes and does not compare across instruments without scaling. ## Indicator snapshot | Attribute | Value | | --- | --- | | Abbreviation | ATR | | Category | Volatility | | Creator / origin | J. Welles Wilder Jr. | | Primary inputs | High; Low; prior Close | | Common settings | 14 periods | | Output | Line/scalar | | Typical range | >=0 | | Primary purpose | Measure dispersion, range, implied uncertainty, or expansion/contraction in price movement. | | Main limitation | ATR measures magnitude, not direction; a high ATR can accompany either a rally or decline. | ## What is Average True Range? Average True Range is a smoothed measure of true range that captures recent price volatility including gaps. It should be treated as a transformation of observable market data, not as an independent source of truth. The useful question is not whether the indicator is “bullish” or “bearish” in isolation, but what specific market property it measures, which assumptions enter the calculation, and whether that information is already duplicated by another tool on the chart. For Swoopr, the canonical profile should separate definition, calculation, interpretation and decision use. That keeps readers from collapsing a descriptive metric into a trading strategy. An indicator can describe trend, momentum, volatility, participation, positioning or risk without providing a complete entry, exit, sizing or portfolio decision. ## What does it measure and why is it used? Measure dispersion, range, implied uncertainty, or expansion/contraction in price movement. The practical value is repeatability: the same inputs and formula can be applied across a defined dataset, allowing users to compare readings through time or across instruments when the calculation convention is held constant. The calculation can still be misleading if the data source, session, adjustment method, smoothing rule or parameter set changes. Two platforms can legitimately report different readings while using different assumptions, so check which conventions a chart uses. ## Formula **TR = max(H−L, |H−Cprev|, |L−Cprev|); ATR is commonly Wilder-smoothed TR over N periods** ### Calculation discipline 1. Fix the instrument, timeframe and session before computing the indicator. 2. Use one documented price/volume source and one corporate-action convention. 3. State every lookback, smoothing method and reset rule. 4. Handle missing data and zero denominators explicitly. 5. Reproduce at least one worked example from raw inputs during QA. 6. Compare the implementation with a second independent calculation before publication. ![Average True Range (14) drawn on a hypothetical 150-day price series generated for this page, not market data. The series runs through an uptrend, a pullback, a range and a second advance. ATR 14 ranges from 1.62 to 3.17 and ends at 2.91.](https://www.getswoopr.com/images/charts/indicator-volatility-average-true-range.webp) *Average True Range (14) on a hypothetical price series generated for this page. The data is invented to show how the indicator behaves through a trend, a pullback and a range; it is not market data and not a forecast. Select the chart to open it full size.* ## How to read Average True Range A higher reading generally means **the instrument has recently moved through larger ranges**. A lower reading generally means **recent ranges are smaller**. That interpretation is descriptive, not predictive. The same numerical state can lead to different outcomes in a strong trend, quiet range, event-driven gap or illiquid market. ### Bullish, bearish and neutral context A bullish interpretation is appropriate only when the reading lines up with the indicator's actual job. For a trend tool, that means direction or trend persistence; for a momentum tool, it means stronger upside momentum; for a volatility measure, “higher” is not bullish at all:it only means larger expected or realized movement. A generic bullish or bearish label therefore does not fit a direction-neutral indicator. A neutral state should be defined when the indicator does not provide enough evidence for its intended job. This is especially important for bounded oscillators near mid-range, volatility gauges near historical medians, or spread measures near long-run norms. ## Common settings The common reference is **14 periods**. This is a starting convention, not a universally optimal parameter. Shorter lookbacks generally respond faster and produce more state changes; longer lookbacks smooth noise but react later. Parameter selection should be tied to the intended decision horizon, then tested over multiple instruments and regimes rather than optimized to one historical period. ## Worked hypothetical interpretation Suppose a researcher calculates Average True Range with the documented settings across a liquid security and observes a material change in the reading. The first step is to state what changed in the underlying input. The second is to ask whether price structure, volume, volatility or the benchmark environment confirms that interpretation. The third is to define what observation would invalidate it. Only after those steps should the indicator feed a strategy rule. This sequence prevents a common error: treating the indicator output as if it arrived independently of the price, volume, options or market data used to calculate it. ## Best and weak market conditions Average True Range (ATR) is most useful when the market property it measures is actually relevant to the decision. It is weakest when the regime changes faster than the lookback, the market is illiquid, the input data are incomplete, or the chosen parameter set is mismatched to the timeframe. A trend indicator tends to struggle in ranges; a mean-reversion oscillator can remain extreme during persistent trends; volume-based measures can break when venue coverage changes; options and on-chain measures can be provider-specific. ## Strengths - Using the prior close in the true range means overnight gaps count toward volatility, which a plain high-minus-low range would miss. - Wilder smoothing reacts gradually, so a single unusual bar changes the average by only one n-th of its excess over the prior value. - Reproducible when the formula and data convention are fixed. ## Weaknesses and false signals - ATR measures magnitude, not direction; a high ATR can accompany either a rally or decline. - Parameter changes can alter timing and classification. - Correlated indicators can create false confidence by repeating the same underlying information. - Historical relationships can fail after market structure or volatility regimes change. - Backtests can be overstated by look-ahead bias, survivorship bias, unrealistic fills or omitted transaction costs. ## Combining Average True Range with other indicators The strongest combination usually pairs different input families rather than similar formulas. Before adding another indicator, identify the specific error it is supposed to catch and measure how often the two signals disagree. High agreement between two price-only oscillators is not necessarily confirmation; it can be arithmetic redundancy. Related entities for this profile include: Bollinger Bands, Donchian Channels, Historical Volatility, IV Percentile, IV Rank, Implied Volatility. ## When not to use it Do not use Average True Range as a standalone forecast or as a substitute for position sizing, liquidity checks, execution planning or fundamental research when those are relevant to the decision. Avoid publishing “best settings” without a defined asset universe, timeframe, cost model and out-of-sample validation. If the indicator depends on proprietary or provider-specific methodology, the provider's own documentation is the authority on how it is calculated. ## Practical checklist - [ ] What exact question is the indicator answering? - [ ] What data series, session and adjustments are used? - [ ] What parameters and smoothing rules are fixed? - [ ] Is the indicator bounded, unbounded or price-denominated? - [ ] Does a second indicator add independent information? - [ ] What market regime is present? - [ ] What would invalidate the interpretation? - [ ] Have slippage, costs and execution constraints been considered? - [ ] Has the calculation been independently reproduced? ## Frequently asked questions ### Is Average True Range a buy or sell signal? No. It is an analytical measure. A trade still needs a hypothesis, trigger, invalidation rule, position size, exit logic and realistic execution assumptions. ### What is the best setting for Average True Range? There is no universal best setting. Start with the conventional reference (14 periods) and test nearby values across instruments, regimes and out-of-sample periods. Favor stable parameter regions over one historical winner. ### Can Average True Range be used by itself? It can describe its specific market property by itself, but using it alone generally leaves other important dimensions:direction, regime, participation, valuation, liquidity or risk:undefined. ### Does Average True Range work on every timeframe? The calculation may be portable, but behavior is not. A 14-period reading on a five-minute chart describes a very different market window from the same setting on a daily chart. Validate the exact timeframe. ### Why does Average True Range give false signals? False signals arise from lag, noise, regime changes, parameter sensitivity, data conventions and the fact that market participants react to new information after the reading is calculated. ### How should Average True Range be backtested? Write rules before testing, use point-in-time data, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample, break results out by regime and compare with a simpler baseline. ## Choose your next step ### Apply - [Average True Range Explained: ATR Stops, Targets, and Position Sizing](https://www.getswoopr.com/learn/technical-analysis/indicators/average-true-range/) Step-by-step use, worked examples and the mistakes to avoid ## Related Swoopr content - Parent hub: [Volatility Indicators](https://www.getswoopr.com/indicators/volatility/) - Related guide: [Average True Range Explained: ATR Stops, Targets, and Position Sizing](https://www.getswoopr.com/learn/technical-analysis/indicators/average-true-range/) - Related indicators: Bollinger Bands, Donchian Channels, Historical Volatility, IV Percentile, IV Rank, Implied Volatility ## Sources and further reading - [TA-Lib Functions](https://ta-lib.org/functions/) - [TradingView built-in indicator list](https://www.tradingview.com/charting-library-docs/latest/ui_elements/indicators/Indicators-List/) ## Editorial and risk note This page is educational content, not individualized investment advice. It does not imply guaranteed prediction, accuracy or outperformance. ## Frequently Asked Questions Is Average True Range a buy or sell signal? No. A higher ATR means recent bars have covered larger ranges, and a lower ATR means they have been smaller. ATR measures the size of movement, not its direction, so a high value can come with a rally or a decline. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions. What is the best setting for Average True Range? Average True Range takes these inputs: high, low and the prior close for each bar; smoothing period n (14 periods is the usual default); a starting ATR, typically the simple average of the first n true ranges. There is no universal best setting for the tunable ones, so test them across instruments, regimes and out-of-sample periods and favor stable parameter regions over one historical winner. Can Average True Range be used by itself? ATR measures the size of movement, not its direction, so a high value can come with a rally or a decline. Because it is expressed in price units and smoothed, it lags sudden changes and does not compare across instruments without scaling. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone. Does Average True Range work on every timeframe? The calculation (TR = max(High - Low, abs(High - prior Close), abs(Low - prior Close)); ATR = (prior ATR * (n - 1) + TR) / n) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it. Why does Average True Range give false signals? ATR is in price units, so a 2 point ATR means different things on a 20 dollar stock and a 500 dollar stock unless it is scaled by price. Since the average is smoothed, it keeps reflecting a large bar for many periods after it occurred and may overstate current conditions. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated. How should Average True Range be backtested? Rebuild Average True Range from high, low and the prior close for each bar using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline. S Swoopr Editorial Team The Swoopr Editorial Team produces independent investment education, research, and tools for understanding markets, evaluating opportunities, and managing risk. All content is educational only and does not constitute personalized investment advice. See our [editorial policy](https://www.getswoopr.com/legal/editorial-policy/) and [corrections policy](https://www.getswoopr.com/legal/corrections-policy/).