What is ATR? The volatility measure that determines where your stop goes

ATR — short for Average True Range — is a volatility indicator that measures how much an asset actually moves in a typical trading candle, in price terms. The common version, ATR-14, averages the true range of the last 14 candles. If a stock's daily ATR is 3 dollars, the meaning is simple: on a normal day this stock travels a distance of about 3 dollars.

Unlike most indicators, ATR says nothing about direction. It answers a different and equally important question: how much noise should you expect along the way? That answer is what determines where it makes sense to place a stop — and how large the position can be.

How ATR is calculated

The True Range of a candle is the largest of three distances: between today's high and low; between today's high and yesterday's close; and between today's low and yesterday's close. The last two measurements exist to capture opening gaps — a day that opened 5% above the previous close was highly volatile even if the candle itself turned out short.

The true range is averaged over 14 periods — the default set by Welles Wilder, who developed the indicator alongside RSI. ATR can be calculated on any timeframe: daily, hourly, or weekly candles, each with its own noise level.

ATR as the basis for stop distance

The principle: a stop should sit outside the asset's normal noise, otherwise it will keep getting hit again and again before the trade idea is even invalidated. A uniform percentage stop — say 2% below entry — ignores the asset's character: in a dormant stock, 2% is a huge range, while in a volatile stock it's within a single morning's swing. A stop derived from ATR — for example, a multiple of the ATR below entry or below the support level — automatically calibrates to each asset.

That's how it works for us too: in TechAnalyzer's setup block, stop distance is derived from the asset's ATR, and after measuring it against the track record we even widened the distance — because we found that stops placed too tight were getting stopped out on noise before the idea had a chance. More on proper placement in the guide Stop-loss.

ATR and position sizing

This is where ATR stops being just another indicator and becomes real risk management. The common method: decide how much money to risk on a single trade (say 1% of the account), divide that amount by the stop distance in price terms — and you get the number of shares. A volatile stock with a wide stop will automatically yield a small position; a calm stock — a larger position. The monetary risk in both is identical.

This is the point many beginners miss: stop distance and position size are two sides of the same decision. Someone who tightens the stop to "reduce risk" without reducing position size hasn't reduced anything — they've only increased the chance of being stopped out on noise. How to weigh this against the potential — in the guide Risk-reward ratio.

Common mistakes with ATR

Four well-known ways to use the right indicator and reach the wrong conclusion:

• Reading direction into it: ATR rises both in a crash and in a surge. It measures the strength of the move, not its sign.
• Comparing raw ATR between stocks: An ATR of 5 dollars on a 50-dollar stock (10%) and on a 500-dollar stock (1%) are different worlds. To compare across assets, divide the ATR by the price.
• Treating the multiplier as a law of nature: 1.5 or 3 times ATR is not a rule. The right multiplier depends on style and timeframe — and it deserves to be measured, not guessed.
• Forgetting that volatility breathes: ATR expands and contracts. A stop calculated during a calm period may be too tight when volatility spikes, for example around earnings reports.