Probability & Forecasting · MANUAL INPUT
Expected Move Calculator
Calculate one- and two-standard-deviation price-move approximations from manual IV and DTE.
How to use this tool
Move size equals underlying price × annual IV × square root of calendar days / 365. The displayed bands are symmetric approximations, not exact lognormal quantiles.
A one-standard-deviation normal range is often associated with about 68% and two with about 95%; these are not guaranteed coverage for an actual stock. Large volatility or long horizons can produce a negative lower approximation, which is labelled outside the positive-price model.
Worked example
For $100 spot, 20% IV and 365 days, the one-SD approximation is $20 or 20%, giving $80–$120. Two SD gives $60–$140.
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Model references and conventions
365 calendar days per year. Continuous rates for theoretical pricing. All examples are illustrative.