Stock Volatility Calculator
Measure how much a stock price is expected to move using 52-week high/low data, ATR, and Beta
Parkinson Estimator
Uses the proven Parkinson method to estimate annualized volatility from the 52-week high/low range
Expected Price Moves
See the expected daily, weekly, and monthly price movements in both absolute and percentage terms
Confidence Intervals
View 1-sigma (68%), 2-sigma (95%), and 3-sigma (99.7%) price ranges for daily trading sessions
Related Keywords & Topics
Stock Volatility Calculator
Stock Data
Optional Inputs
14-day ATR from your charting platform. Used for ATR-based volatility estimate.
Stock beta from any finance portal. Used for beta-adjusted volatility (assumes S&P 500 annualized vol of ~15%).
Volatility Analysis
Enter stock price and 52-week high/low to calculate volatility
Complete Guide to Stock Volatility
What is Stock Volatility?
Volatility measures how much a stock's price fluctuates over a given period. A stock with high volatility swings sharply up and down, while a low-volatility stock moves in smaller, more predictable steps. It is typically expressed as an annualized percentage.
Traders and investors use volatility to size positions, set stop-losses, price options, and gauge overall market risk. If you trade options, volatility directly affects the premium you pay or collect. If you manage a portfolio, understanding each holding's volatility helps you balance risk and reward. You can explore related calculations with our Options Profit Calculator and Trade Risk Calculator.
Volatility Formulas
Parkinson Historical Volatility (used in this calculator):
HV = ln(High / Low) / (2 x sqrt(ln(2)))
Annualized Volatility = HV x 100
Where: High = 52-week high price | Low = 52-week low price | ln = natural logarithm
ATR-Based Volatility (alternative):
ATR Vol = (ATR / Price) x sqrt(252) x 100
Where: ATR = Average True Range (14-day) | 252 = trading days per year
Expected Daily Move:
Daily Move = Price x (Annualized Vol% / 100) / sqrt(252)
Why Measure Volatility?
Better Position Sizing
A volatile stock requires smaller position sizes to keep your dollar risk constant. Knowing the expected daily move helps you calculate exactly how many shares to trade.
Smarter Stop-Loss Placement
Place stop-losses outside the normal daily noise. A 2-sigma stop means there is only a 5% chance the price moves that far in a single day under normal conditions.
Options Pricing Insight
Option premiums rise with volatility. Compare the calculator's historical volatility against implied volatility to spot overpriced or underpriced options.
Portfolio Risk Management
Balancing high-volatility and low-volatility holdings smooths your equity curve. Track each stock's vol alongside your stock return calculations for a full picture.
Tips for Using Volatility
Tip 1: Compare the Parkinson estimate with ATR-based volatility. If both agree, you have a reliable reading. Large differences suggest recent price behaviour differs from the yearly trend.
Tip 2: Use the 2-sigma (95%) confidence interval as a guide for where "normal" daily trading ends and "unusual" moves begin. Moves beyond 2-sigma often signal news events or sentiment shifts.
Tip 3: Volatility is not direction. A high-volatility stock can still trend strongly upward. Pair volatility analysis with trend and momentum indicators before making trading decisions.
Common Mistakes
Confusing Volatility with Risk
Volatility measures price swings in both directions. A stock that surges 50% in a year is "volatile" but profitable. Always combine volatility with your directional thesis and position-sizing rules.
Ignoring Volatility Clustering
Volatility tends to cluster: calm periods follow calm periods, and turbulent days follow turbulent days. A single annualized number hides these regimes. Check recent ATR alongside the yearly estimate.
Using Volatility Alone to Size Options Trades
Historical volatility tells you what happened. Options are priced on implied volatility, which reflects what the market expects. Always compare the two before selling or buying premium.