Average True Range (ATR) is a volatility indicator developed by J. Welles Wilder Jr. and introduced in his 1978 book New Concepts in Technical Trading Systems. Unlike trend indicators, ATR measures how much an instrument moves per bar on average — regardless of direction — making it the standard tool for dynamic stop placement, volatility-adjusted position sizing, and breakout confirmation.
Key Takeaways
- ATR uses “true range” rather than simple high-minus-low, capturing overnight gaps that a basic range calculation misses.
- The three core ATR applications are stop placement (1.5×–3× ATR from entry), position sizing (dollar risk ÷ ATR stop distance = shares), and breakout filtering (require 0.5×–1× ATR clearance above resistance before entering).
- ATR is a lagging realized-volatility measure — it understates risk into binary events like earnings reports and FOMC announcements where implied volatility spikes sharply.
How to Calculate Average True Range
The formula starts with the true range for each bar — the greatest of three values:
True Range = MAX(
High − Low,
|High − Prior Close|,
|Low − Prior Close|
)
The absolute values in lines 2 and 3 capture gap openings. If a stock closes at $50 and gaps up to open at $54, a simple high-minus-low would miss the $4 gap entirely. True range does not.
ATR is then a smoothed average (Wilder’s smoothing, not a simple MA) of the true range over 14 periods by default:
ATR(14) = [(Prior ATR × 13) + Current True Range] / 14
The same formula applies across all timeframes — a 14-bar ATR on a 5-minute chart measures intraday volatility; on a weekly chart it measures multi-week swings.
Quick Reference
| Aspect | Detail |
|---|---|
| Formula | Smoothed average of true range over N bars (default N = 14) |
| Good Range (SPY) | $4–$6 calm markets; $15–$25 high-volatility regimes; exceeded $30 in March 2020 |
| Stop Multiplier | 1.5×–3× ATR below entry; 2× ATR is the common default |
| Warning Signs | ATR rising fast into an event — may understate actual gap risk; ATR at multi-month lows — volatility contraction, breakout may be imminent |
Practical Example
A swing trader is watching AAPL at $185. The 14-day ATR is $3.20. The plan is a long entry on a breakout above $187 resistance.
Step 1 — Breakout filter. To avoid a false breakout, the trader requires a confirmed close at least 0.5× ATR above resistance: 0.5 × $3.20 = $1.60, so the entry triggers only on a close above $188.60.
Step 2 — Stop placement. The stop is set at 2× ATR below the entry price: $188.60 − (2 × $3.20) = $188.60 − $6.40 = $182.20. This level accounts for normal daily noise without giving up excessive risk.
Step 3 — Position sizing. With a $20,000 account risking 1% per trade ($200), position size = $200 ÷ $6.40 = 31 shares ($5,746 deployed, 28.7% of account).
Step 4 — Trailing exit. If AAPL climbs to $197 (roughly a 3:1 reward-to-risk ratio), the Chandelier Exit trails at 3× ATR below the highest close since entry: $197 − $9.60 = $187.40, locking in most of the gain automatically.
Average True Range, or ATR, measures how much a stock typically moves per day. Traders use it to set stop losses that account for normal market noise, size their positions based on actual volatility, and confirm breakouts before entering a trade.
Common Mistakes
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Using ATR as a direction signal. ATR tells you how much price moved, not which way. A rising ATR during a downtrend means volatility is high — not that a reversal is coming. Pair ATR with ADX or Bollinger Bands for directional context.
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Ignoring binary-event risk. ATR reflects recent realized volatility. Before an earnings report or FOMC meeting, a stock with a 14-day ATR of $3 may gap $12 overnight. Check the options market’s implied move — not just ATR — before holding through events.
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Using the same ATR multiplier for all setups. A 2× ATR stop fits most swing setups, but volatile small-caps may require 3× to avoid noise-driven exits, while low-volatility large-caps may work fine at 1.5×. Backtest your multiplier on the specific ticker and timeframe.
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Overlooking ATR contraction as a setup signal. When ATR drops to multi-month lows — such as in an NR7 pattern (narrowest 7-day range) — it signals volatility contraction that historically precedes large directional moves. This makes low ATR as valuable a filter as high ATR.
How JournalPlus Tracks Average True Range
JournalPlus logs the ATR at entry for every trade, so you can review whether your stop distances were proportional to actual volatility or whether you were systematically over- or under-risking relative to the market environment. The analytics dashboard surfaces ATR-adjusted stop efficiency across your trade history, making it straightforward to calibrate your multiplier over time.
