Volatility & ATR Calculator
Calculate Average True Range and historical volatility for any stock, crypto, or forex pair using live market data.
Free — no signup, no ads, instant results
Inputs
Who Is This For?
This calculator is for traders who need to know how volatile an asset is before sizing positions or setting stops. It is useful for anyone trading stocks, crypto, forex, or futures who wants to make data-driven decisions about stop loss placement, position sizing, and risk management.
When to Use This Calculator
- Before entering a trade to set ATR-based stop losses
- When comparing volatility across different assets
- When adjusting position size for volatile vs calm markets
- When evaluating whether current volatility is historically high or low for an asset
Formula
Average True Range (ATR) was developed by J. Welles Wilder Jr. in 1978. It measures volatility by calculating the True Range for each period:
TR = max(High - Low, |High - Prev Close|, |Low - Prev Close|)
ATR is then a smoothed average of these True Range values over the selected period (default 14). Use ATR to set stop losses, determine position sizes, and compare volatility across different assets.
Worked Example
Scenario: AAPL has a 14-day ATR of $3.25 and the last price is $185.
Step 1: ATR as % of price = $3.25 / $185 = 1.76%.
Step 2: 1.5x ATR stop distance = $3.25 x 1.5 = $4.88 from entry.
Step 3: Annualized volatility of 28% means AAPL typically moves within a 28% range per year (one standard deviation).
Result: Set your stop at least $4.88 away from entry to avoid being stopped out by normal daily fluctuations.
Assumptions & Edge Cases
- Uses daily OHLC data from Yahoo Finance
- ATR is smoothed using Wilder's method (exponential smoothing)
- Historical volatility is annualized assuming 252 trading days
- Past volatility does not guarantee future volatility — regime changes can shift ATR dramatically
- Data may be delayed — always verify with your broker's live feed
Frequently Asked Questions
ATR measures market volatility by calculating the average range of price movement over a specified period (typically 14 days). It accounts for gaps by using the True Range, which considers the previous close. Higher ATR means more volatility.
A common method is placing your stop loss 1.5x to 2x ATR away from your entry price. This gives the trade enough room to breathe while staying within a statistically normal price range. Tighter stops (1x ATR) reduce risk but increase the chance of being stopped out by normal volatility.
Historical volatility (HV) is the annualized standard deviation of daily returns, expressed as a percentage. It tells you how much an asset's price typically fluctuates over a year. A stock with 30% HV means its price is expected to move within a 30% range annually (one standard deviation).
ATR measures the average daily price range in dollar terms — useful for setting stop losses and position sizes. Historical volatility is an annualized percentage — useful for comparing volatility across assets with different prices. Both measure volatility, just from different angles.