Average true range (ATR): Using volatility for position sizing and risk control

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Capturing the full range of price volatility.

© Ljupco Smokovski/stock.adobe.com; Photo illustration Encyclopædia Britannica, Inc

Ask an experienced trader about their biggest challenge in achieving consistent profitability, and they’ll likely talk about volatility—not just the direction of price, but how aggressively and unpredictably it moves. Volatility can shake you out of a position prematurely or cause you to risk too much in a quiet market. That’s where the average true range (ATR) indicator comes in. It doesn’t just measure how much an asset moves—it helps you recognize when volatility is outside its normal range so you can adjust your risk.

Developed by technical analyst J. Welles Wilder Jr. in 1978, ATR can be used across different markets and time frames. Although it doesn’t forecast price direction, it can help your decision-making about position sizing, placement of stop-loss orders, and overall trade management. This makes it a key component of risk-focused trading strategies.

Average true range is a technical indicator that measures market volatility by calculating the average of true ranges over a specified period. Modern trading platforms will make the calculations for you, but it’s good to understand the math behind the indicator. 

The “true range” represents the greatest out of three values:

This three-pronged approach makes ATR useful for capturing volatility that occurs between trading sessions, including overnight price gaps. The ATR is a simple moving average (SMA) of true ranges over n periods (typically 14). As with all moving averages, each day a new data point is added to the ATR calculation and the most aged data point (e.g., the one from 15 days ago) is dropped. 

The strength of this indicator lies in its application to risk management. You can use it to determine appropriate position sizes and the placement of stop orders (“stop-loss”) based on market volatility rather than arbitrary percentages or fixed dollar amounts.

Consider this real-world example of how ATR can inform a trading strategy (see figure 1).

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Figure 1: TREND-LOVIN’. As a 2024 rally in shares of Applovin Corp. (APP) accelerated, so did its average true range (ATR). An ATR-based stop-loss would allow you to ride the trend further without getting stopped out too soon. For educational purposes only.

Source: StockCharts.com. Annotations by Encyclopædia Britannica, Inc.

Suppose you opened a long position in Applovin Corp. (APP) in September 2024, just as an uptrend was getting underway (using the 20-day moving average, the blue line in figure 1, as a guide). As a swing trader, you planned to hold the trade for a few weeks or months depending on the strength of the trend.

Using the ATR as a could give you a baseline volatility to inform a stop-loss strategy. For example, suppose you decided to set a trailing stop-loss level (i.e., a stop that adjusts to the current price of the stock) at 2x the ATR. If you purchased shares at $100 (when the ATR was about 7.5), your initial stop-loss level would be ($100 – $15) = $85. But as the rally picked up steam, so did the ATR. By February 2025 the ATR had risen to 30, meaning it would take a fall in APP shares of $60 to trigger the stop.

In contrast, if you had set a fixed stop level of $15, you would likely have been stopped out at one of several moves down along the way. An ATR-based stop-loss strategy can give the stock room to move within its current volatility range before triggering an exit.

Popular indicators like the Cboe Volatility Index (VIX) and Bollinger Bands also measure market volatility, but ATR offers significant advantages over both.

The VIX is designed to be forward-looking, a gauge of volatility based upon options pricing. ATR is a more straightforward snapshot of the recent volatility trend. It’s more descriptive instead of predictive, giving you a baseline of what “normal” volatility has been. If price starts to exceed the normal range, it’s a clue that something significant may be changing in the dynamics of the underlying asset.

Compared to Bollinger Bands, which are calculated using volatility, price levels, and moving averages, ATR offers a purer measure of volatility. Bollinger Bands show where prices sit relative to recent ranges, whereas ATR focuses solely on the magnitude of price movements.

This purity is a key differentiator. Because ATR relies only on price data and disregards volume, it can be used with any asset—stocks, forex, commodities, cryptocurrencies, and more. In theory, you could even use it on nontraditional assets like baseball cards or non-fungible tokens (NFTs), as long as you have accurate historical price data.

In addition to basic risk management, average true range can also be used for exit strategies and market timing decisions.

Breakout confirmation strategies. When price breaks above resistance or below support levels, ATR can help determine if the move represents a genuine breakout or a false signal. For example, breakouts that coincide with an increased ATR reading are generally more reliable than those occurring during low-volatility periods.

Volatility-based entry timing. When the ATR contracts to unusually low levels, it’s often a signal that a significant price move is coming, as contractions often precede expansions. This is because markets tend to build energy during quiet periods before the next directional push. Conversely, extremely high ATR readings may signal exhaustion and potential reversal opportunities.

Dynamic profit targets. Rather than using fixed price levels, you can set profit goals at two or three times the current ATR value, adjusting expectations to match volatility and improving your odds of reaching them.

And as with most technical analysis tools, combining ATR with other indicators can give you a broader picture. For example, pairing it with moving averages helps identify trend strength and potential reversal points, while combining it with momentum oscillators like the relative strength index (RSI), also created by J. Welles Wilder, can improve entry and exit timing.

Average true range isn’t meant to predict price direction, but it can play a valuable role in helping you gauge whether current market volatility is typical or unusual. By measuring how much a stock or other asset typically moves, ATR provides useful context for setting stop-loss levels, sizing positions, and managing trades more effectively. Whether used on its own or alongside other indicators, it offers a practical way to align risk management with current market conditions.

This article is intended for educational purposes only and not as an endorsement of a particular financial strategy. Encyclopædia Britannica, Inc., does not provide legal, tax, or investment advice.