What Is ATR (Average True Range)?

Average True Range (ATR) is a volatility indicator developed by J. Welles Wilder Jr. in 1978. Unlike indicators that measure price direction, ATR measures how much a stock moves on average — its volatility.

ATR tells you: "This stock typically moves $X per day." That single number is incredibly useful for setting stop losses, sizing positions, and filtering trades.

How ATR Is Calculated

ATR is calculated in two steps:

Step 1: True Range

For each trading day, True Range is the greatest of these three values:

Current High minus Current Low — the day's full range
Current High minus Previous Close — catches overnight gap ups
Current Low minus Previous Close — catches overnight gap downs

The "true" range accounts for gaps, which a simple high-minus-low calculation would miss.

Step 2: Average the True Range

ATR is typically a 14-period moving average of the True Range. Most platforms use an exponential moving average:

ATR = ((Previous ATR × 13) + Current TR) / 14

A higher ATR means the stock is more volatile. A lower ATR means it's quieter.

Example

If AAPL has a 14-day ATR of $3.50, that means Apple stock moves an average of $3.50 per day. If TSLA has an ATR of $12.00, Tesla is roughly 3.4x more volatile.

Why ATR Matters for Traders

ATR is arguably the most important indicator for risk management. Here's why:

1. ATR-Based Stop Losses

Fixed dollar stop losses are flawed. A $2 stop on a $150 stock that moves $5/day is too tight — you'll get stopped out by normal noise. A $2 stop on a $20 stock that moves $0.50/day is too wide — you're risking too much.

ATR solves this by scaling your stop to the stock's actual volatility:

Tight stop: 1× ATR below entry
Standard stop: 1.5× ATR below entry
Wide stop: 2× ATR below entry

For a stock at $100 with ATR $3:

Tight stop: $97 (1× ATR)
Standard stop: $95.50 (1.5× ATR)
Wide stop: $94 (2× ATR)

This approach adapts automatically to each stock's behavior. Volatile stocks get wider stops. Calm stocks get tighter stops.

2. ATR-Based Position Sizing

The ATR-based position sizing formula ensures you risk the same dollar amount on every trade, regardless of volatility:

Shares = Risk Amount / (ATR Multiplier × ATR)

Example: You have a $50,000 account and want to risk 1% ($500) per trade. AAPL has an ATR of $3.50, and you use 1.5× ATR for stops.

Shares = $500 / (1.5 × $3.50) = 95 shares

For TSLA with ATR of $12.00:

Shares = $500 / (1.5 × $12.00) = 27 shares

You risk $500 on both trades, but own fewer shares of the more volatile stock. This is how professional traders normalize risk.

3. ATR for Trade Filtering

ATR% (ATR as a percentage of price) helps you compare volatility across stocks at different price levels:

ATR% = (ATR / Price) × 100

A $200 stock with ATR $4 has ATR% of 2%
A $20 stock with ATR $0.80 has ATR% of 4%

Day traders typically look for stocks with ATR% above 2–3% — enough movement to profit from intraday swings. Below 1.5% ATR is usually too quiet for day trading.

4. ATR for Profit Targets

If ATR tells you how far a stock typically moves, you can set realistic profit targets:

Conservative target: 1× ATR from entry
Standard target: 1.5–2× ATR from entry
Aggressive target: 3× ATR from entry

A common day trade setup uses a 1.5 ATR stop and 2 ATR target, giving a 1.33:1 reward-to-risk ratio.

Normalized ATR (NATR)

Normalized ATR (NATR) expresses ATR as a percentage of closing price, making it directly comparable across stocks:

NATR = (ATR / Close) × 100

NATR is useful for:

Screening for volatile stocks (NATR > 3%)
Comparing volatility across sectors
Identifying periods of compression (low NATR) that often precede breakouts

ATR Period Settings

The default ATR period is 14, but different timeframes suit different trading styles:

Trading Style	ATR Period	Timeframe
Scalping	7–10	1-min to 5-min chart
Day trading	14	5-min to 15-min chart
Swing trading	14–21	Daily chart
Position trading	21–50	Daily to weekly chart

Shorter periods make ATR more reactive to recent volatility. Longer periods smooth it out.

Common ATR Mistakes

Mistake 1: Using ATR as a Directional Signal

ATR does not tell you whether a stock will go up or down. A rising ATR means the stock is becoming more volatile, not that it's bullish. A falling ATR means the stock is calming down, not that it's bearish.

Mistake 2: Fixed-Dollar Stops on Different Stocks

Using the same $2 stop loss on every stock ignores volatility. Use ATR-based stops instead.

Mistake 3: Ignoring ATR Expansion

When ATR suddenly expands (e.g., doubles in a few days), it often signals a regime change — earnings, news, or a market-wide event. Tighten risk management during ATR expansion.

Mistake 4: Using ATR on Very Short Timeframes Without Adjustment

On 1-minute charts, ATR values can be tiny and noisy. Consider using ATR from a higher timeframe (5-min or 15-min) for stop placement even when trading on shorter timeframes.

How Tradewink Uses ATR

ATR is deeply integrated into Tradewink's autonomous trading pipeline:

Screening: The day trade screener calculates ATR% for every candidate. Stocks with insufficient ATR% are filtered out — they won't produce enough intraday movement.
Stop-loss placement: Every trade uses an ATR-based stop loss (default 1.5× ATR). This scales automatically to each stock's volatility.
Position sizing: The PositionSizer uses ATR to calculate position size. Risk per trade is fixed as a percentage of account equity, then divided by the ATR-based stop distance.
Trailing stops: As a position moves in your favor, the trailing stop is updated using ATR intervals, keeping the stop at a "normal noise" distance from the current price.
Profit targets: Target prices are set at multiples of ATR from entry (typically 2× ATR for day trades).
Regime-aware sizing: When ATR expands significantly, the system reduces position sizes to maintain consistent risk.

Key Takeaways

ATR measures volatility — how much a stock moves on average — not direction
Use ATR for stop losses (1–2× ATR), position sizing, and profit targets
ATR% (ATR as percent of price) lets you compare volatility across stocks
Default 14-period ATR works for most traders; adjust shorter for scalping, longer for swing trading
Never use fixed-dollar stops — let ATR scale your risk to each stock's actual behavior
AI trading systems like Tradewink use ATR throughout the entire trade lifecycle, from screening to exit

ATR Indicator: The Complete Guide to Average True Range for Traders