Expected Move Calculator
The expected move is the one standard deviation price range an options market implies for an underlying over a chosen horizon, the band where price is expected to finish about two thirds of the time. It is a direct function of implied volatility and time, scaled by the square root of the time fraction. This calculator takes the underlying price, the annualized implied volatility, and the days to expiration, then returns the expected dollar move, the upper and lower one standard deviation prices, and the wider two standard deviation range.
Expected move formula
Expected move = price * (IV / 100) * sqrt(days / 365)
Upper price (1 SD) = price + expected move
Lower price (1 SD) = price - expected move
Two SD move = 2 * expected move
The one standard deviation band contains the underlying about 68 percent of the time under a normal distribution; the two standard deviation band about 95 percent. Volatility is scaled to the horizon by the square root of the time fraction.
Using the result
- Use the at-the-money implied volatility for the expiration you are studying.
- Some traders use 252 trading days instead of 365 calendar days; this tool uses calendar days.
- The range is symmetric in this lognormal approximation; very long horizons skew slightly upward in reality.
- Compare the expected move to a strangle or iron condor's breakevens when choosing strikes.
- Real markets have fat tails, so large moves beyond two standard deviations happen more than the model implies.
Expected move: frequently asked questions
What is the expected move of a stock?
The expected move is the one standard deviation price range an option market implies for an underlying over a given period. Roughly two thirds of the time the price is expected to stay within this range. It is derived from the implied volatility priced into options, not a forecast of direction.
How do you calculate the expected move?
The expected move equals the underlying price times the annualized implied volatility times the square root of days to expiration divided by 365. The result is a dollar amount; the price is expected to finish within plus or minus that amount one standard deviation of the time.
Why use the square root of time?
Volatility scales with the square root of time under the standard random-walk assumption used in option pricing. A 30-day move is not twice a 15-day move; it is the square root of two times as large. The square-root rule converts an annual volatility figure into the volatility for a shorter horizon.
What does one standard deviation mean here?
Under a normal distribution, about 68 percent of outcomes fall within one standard deviation of the mean. So the expected move range is the band the market prices as containing the underlying about two thirds of the time by expiration. A two standard deviation range (about 95 percent) is double the expected move.
Is the expected move a guarantee?
No. The expected move is a probabilistic range implied by current option prices and a normal-distribution assumption. Real returns have fatter tails than the normal model, so large moves happen more often than the model predicts. Use it as a planning range, not a boundary the price cannot cross.
Official sources
- U.S. SEC Investor.gov: Options and implied volatility glossary.
- The Options Clearing Corporation (OCC): Standardized options education.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.