ATR Indicator Guide: Measuring Volatility for Stops

Indicators tell you where price might go. ATR tells you how violently it might get there — and that's exactly what a good stop needs.

The Average True Range (ATR), introduced by J. Welles Wilder in 1978, measures average price movement per period. It does not predict direction — it measures volatility, and that makes it the most useful indicator for placing stops.

The True Range

Wilder defined the True Range as the largest of three values for each period:

TR = max(
  High − Low,
  |High − Previous Close|,
  |Low − Previous Close|
)

Using the previous close handles gaps: a market that gaps up still has a large "true" range even if the day's high–low looks small.

The ATR formula

The ATR is a moving average of the True Range, usually over 14 periods:

ATR(14) = (previous ATR × 13 + current TR) / 14

Worked example — if recent TRs are $1.80, $2.10, $2.00, $2.20, $2.40:

ATR ≈ average ≈ $2.10 per period

A stock moving ~$2.10/day gives you a realistic yardstick for a daily stop.

What ATR tells you

ATR reading	Meaning
Rising	Volatility increasing — widen stops, expect bigger moves
Falling	Volatility decreasing — tighten stops, expect smaller ranges
Multi-year high	Volatility extreme — reduce size
Multi-year low	The calm before a breakout

Using ATR for stops

The classic method: place your stop a multiple of ATR away from entry.

Stop distance = Entry ± (ATR × multiplier)

Common multipliers:

Multiplier	Style	What it filters
1.5 × ATR	Tight	Day trading, scalping
2.0 × ATR	Balanced	Swing trading (most common)
3.0 × ATR	Wide	Long-term, volatile markets

Worked example — long at $50, ATR = $1.50, 2× multiplier:

Stop = $50 − (1.50 × 2) = $47
Risk per share = $3

Plug the entry, stop, and account risk into the stop loss calculator and the position size calculator to get the correct order size.

Why ATR beats fixed-percent stops

Method	Problem
Fixed % (e.g. 2%)	Same stop in calm and volatile markets — too tight when it's wild, too wide when it's quiet
Fixed $ amount	Ignores the instrument's own volatility
ATR-based	Adapts to current volatility — the market sets the stop

Other uses of ATR

1. Position sizing — risk a fixed $ amount; divide it by (ATR × multiplier) to get shares
2. Profit targets — target 2× or 3× the stop distance for a consistent RR
3. Volatility filter — skip trades when ATR is at extremes (too wild) or dead (no movement)
4. Trailing stop — move the stop to (price − 2× ATR) as price advances

Common mistakes

• Multiplier too tight — 1× ATR stops get stopped out by noise
• Using it across timeframes blindly — ATR on a 1-minute chart is tiny; on a daily chart it's meaningful
• Forgetting to update as volatility changes — re-check ATR before each trade
• No RR check — a wide ATR stop still needs a target that gives a favourable risk-reward

Summary

ATR measures volatility, not direction. Use it to set stops that respect how much the market actually moves — and to size positions so a fixed dollar risk holds across calm and violent conditions alike. It's the single most useful indicator for risk management.