Average True Range is the most important volatility measurement in trading. Developed by Welles Wilder in 1978, ATR is not a directional indicator — it tells you nothing about where price will go, only how much it is likely to move. This makes it the foundation of professional risk management, position sizing, and stop placement.
ATR was developed by J. Welles Wilder and first published in his 1978 book 'New Concepts in Technical Trading Systems', the same book that introduced RSI and the Parabolic SAR. Wilder recognised that simple high-minus-low range calculations missed crucial information — particularly overnight gaps.
True Range takes the greatest of three values: Current High minus Current Low. Absolute value of Current High minus Previous Close. Absolute value of Current Low minus Previous Close.
The second and third calculations capture gaps. If a stock closes at $50 and opens the next day at $55, the low-to-high range might only be $2 — but the true movement from the previous close is $7. ATR captures this full picture.
ATR(14) = Smoothed average of 14 True Range values. Wilder used a specific smoothing method: ATR = ((Previous ATR × 13) + Current TR) / 14. This is the same smoothing used in his RSI calculation and it prevents old data from being entirely dropped, giving recent volatility more weight while retaining historical context.
An ATR of $3.50 on a $50 stock means the average daily move is 7% of the stock's price. An ATR of $3.50 on a $500 stock means the average daily move is only 0.7%. Same ATR number, completely different risk profiles — which is why normalising ATR as a percentage of price is essential for cross-asset comparison.
The most valuable application of ATR is in setting stop losses that are calibrated to actual market volatility rather than arbitrary dollar or percentage amounts. A stop placed too close gets triggered by normal noise. A stop placed too far risks excessive capital.
The most widely used approach is placing stops at a multiple of ATR from the entry price. Common multiples range from 1.5 to 3 depending on the strategy, timeframe, and volatility environment.
| Strategy Type | ATR Multiple | Rationale |
|---|---|---|
| Day trading scalp | 1.0–1.5x ATR | Tight, quick in/out, small moves targeted |
| Swing trade | 1.5–2.0x ATR | Balance between protection and breathing room |
| Position trade | 2.0–3.0x ATR | Wider stop to survive retracements |
| Trend following | 2.5–3.5x ATR | Maximum breathing room for extended holds |
ATR changes over time. As volatility expands, your stops should widen. As volatility contracts, they can tighten. Professional traders recalculate ATR-based stops regularly — particularly important for longer-hold strategies where the volatility environment can shift significantly during the trade.
Never place a stop within 1 ATR of your entry in normal market conditions. The daily range alone is likely to test that level, triggering a stop that has nothing to do with your trade thesis being wrong. Professional rule: if your stop is less than 1 ATR from entry, you are positioned too early or the setup is not yet confirmed.
The most powerful and underused application of ATR is position sizing. The goal is to risk the same dollar amount on every trade, regardless of which asset you are trading or how volatile it is.
Shares/Contracts = Risk per Trade ($) divided by (ATR × ATR Multiple)
Example: Account of $50,000. Risk 1% per trade = $500 risk. ATR of the stock = $2.50. ATR multiple for stop = 2.0. Stop distance = $5.00. Position size = $500 / $5.00 = 100 shares.
This means if the trade hits your stop, you lose exactly $500 — 1% of your account — regardless of the stock's price, volatility, or sector. This normalisation is the foundation of professional risk management.
A $3 ATR on a $10 stock means enormous volatility. A $3 ATR on a $400 stock means minimal volatility. Without ATR-based sizing, naive dollar-amount stops produce wildly inconsistent risk. With ATR-based sizing, every trade has the same expected loss if stopped out.
Beyond stops and sizing, ATR is a powerful regime identification tool. Expanding ATR signals a volatile, high-opportunity environment. Contracting ATR signals compression — often preceding a breakout.
When ATR contracts to multi-month lows, the market is compressing energy. This is the environment where Bollinger Band squeezes develop, where accumulation and distribution occur beneath a quiet surface. Breakouts from ATR compression tend to be more sustained because they represent a genuine shift from equilibrium.
Rapidly rising ATR signals a fast, volatile market. Spreads widen, slippage increases, and stops need to be wider. Smaller position sizes are essential. In a fast market, everything that worked in a quiet market needs to be recalibrated.