Every trader eventually asks the same question: how far away should the stop go? Place it too close and normal price noise ends the trade early. Place it too far and a single loss can do outsized damage. Average True Range (ATR) is one of the most common tools for connecting stop distance to how much a market actually moves. This article explains how ATR is calculated, how traders translate it into stops and position size, and where the method falls short.
Educational content, not investment advice.
What ATR measures
ATR was introduced by J. Welles Wilder Jr. in his 1978 book New Concepts in Technical Trading Systems. It does not indicate direction. It measures volatility: the typical distance a security travels over a given bar, including gaps between sessions.
Each bar’s “true range” is the largest of three values:
- The current high minus the current low.
- The absolute difference between the current high and the previous close.
- The absolute difference between the current low and the previous close.
Including the previous close matters because overnight gaps are part of real risk. A stock that gaps up and then trades in a narrow range still moved a long way. ATR is then a moving average of true range, with 14 periods as the common default. The “period” depends on the chart: 14 daily bars on a daily chart, 14 five-minute bars on a five-minute chart.
Why volatility-based stops
A fixed stop, such as 50 cents or 2%, treats every market the same. But a quiet large-cap stock and a fast-moving small-cap can differ many times over in typical movement. A stop that is sensible for one may be meaningless for the other.
ATR-based stops adjust automatically. When volatility expands, the stop widens and position size shrinks. When volatility contracts, the stop tightens and size can grow, still within the trader’s risk limit. The goal is a stop placed outside ordinary noise, so that being stopped out signals that the trade idea may have failed rather than that the market simply breathed.
A simple ATR stop framework
A common approach multiplies ATR by a chosen factor and measures from the entry price or a reference level:
- Long position: stop = entry price minus (multiplier x ATR).
- Short position: stop = entry price plus (multiplier x ATR).
Multipliers between 1 and 3 are often discussed, with shorter-term traders tending toward smaller values and swing traders toward larger ones. There is no universally correct multiplier. The right choice depends on the strategy, the timeframe and, ideally, testing on historical data.
Worked example with hypothetical numbers
The figures below are invented purely to illustrate the arithmetic. They do not describe any real security or recommend any trade.
| Item | Value |
|---|---|
| Account equity | $20,000 |
| Risk per trade | 1% of equity = $200 |
| Hypothetical entry price | $50.00 |
| 14-period ATR | $1.00 |
| Stop multiplier | 2 x ATR = $2.00 |
| Stop price (long) | $48.00 |
| Position size | $200 / $2.00 = 100 shares |
If volatility doubled and ATR rose to $2.00, the same 2x multiplier would put the stop $4.00 away, and the same $200 risk budget would allow only 50 shares. The dollar risk stays constant while the share count flexes. This is the central benefit of the method: risk is defined first, and size follows from the stop.
Choosing the timeframe
ATR should match the chart the trader actually uses to make decisions.
- Intraday traders often use ATR on short bars, such as one-minute to fifteen-minute charts, to size stops against current session volatility.
- Swing traders typically use daily ATR, since positions are held for days and overnight gaps matter.
Mixing the two, such as a daily ATR stop on a trade planned to last minutes, produces stops that are too wide for the plan and positions that are too small to be useful.
Common ways ATR stops fail
- Ignoring market structure. A stop placed by formula can land in the middle of an obvious support or resistance zone. Many traders adjust stops to sit beyond a structural level, then recalculate size.
- Gaps and slippage. A stop order is not a guaranteed price. Overnight gaps, news and fast markets can fill well beyond the stop, so realized loss can exceed the planned amount.
- Lagging data. Because ATR is an average, it reacts after volatility shifts. A sudden spike, such as around a scheduled economic release or earnings, may not yet be reflected in the reading.
- Over-optimizing the multiplier. Tuning the multiplier until a backtest looks perfect usually fits past noise rather than future behavior.
- Stops that are too wide for the account. If the ATR-based stop requires a position size too small to be worthwhile, the honest conclusion may be to skip that instrument rather than shrink the stop.
Trailing stops with ATR
ATR is also used to trail stops. In a long trade, the stop may be set at a multiple of ATR below the highest close since entry and moved up, never down, as price advances. This lets the stop follow the trend at a distance proportional to volatility. The tradeoff is familiar: a tighter trail protects open gains but exits sooner, while a looser trail tolerates pullbacks but gives back more.
Putting it into a routine
- Decide the maximum dollar risk per trade before looking at any chart.
- Read the ATR on the timeframe being traded.
- Set the stop using a multiplier tested in advance, then check it against nearby structure.
- Calculate position size from the stop distance, not the other way around.
- Record the ATR, multiplier, planned risk and actual result in a trade journal so the approach can be reviewed with real data.
The bottom line
ATR gives traders an objective, repeatable way to relate stop distance and position size to current volatility. It does not predict direction, avoid gaps, or guarantee that a stop will fill at the intended price. Used as one part of a defined risk plan, alongside position sizing and testing, it can help keep losses consistent across very different markets.
Educational content, not investment advice. Trading involves substantial risk of loss, and all examples are hypothetical.
