Implied Volatility Calculator

Implied volatility (IV) is the volatility that, plugged into an option pricing model, reproduces the option's market price. It is the market's estimate of how much the underlying will move, and it is how options traders compare prices across strikes, expiries and assets. Because there is no formula to solve for IV directly, it is found by trial: guess a volatility, price the option, adjust, repeat. This calculator does that search with the Black Scholes model and also shows the expected one standard deviation move to expiry.

Calculator#

How it works#

The calculator searches for the volatility σ that makes the Black Scholes price equal the market price, using bisection between 0.01% and 500% for 100 steps.

Find σ such that BlackScholes(S, K, T, r, q, σ) = Market price
Expected 1 SD move = S × σ × √T

Use the mid price between bid and ask for the most meaningful result. If the price is at or below the option's intrinsic value, no volatility can explain it. See Implied Volatility (IV) and Black-Scholes and Greeks Calculator.

Expected move for shorter periods#

Traders often use the at the money straddle price as a quick estimate of the expected move into an event such as earnings. See Straddle and Earnings Trading.

Reading implied volatility#

Common pitfalls#

1. Using last trade prices that may be stale; use the bid ask midpoint.
2. American options: Black Scholes IV can be slightly off for deep in the money American puts. See American vs European Options.
3. Wrong dividends distort IV, especially for longer dated options.
4. Very short expiries produce unstable IV estimates.
5. Comparing IV with historical volatility without considering upcoming events. See Historical and Realized Volatility.

Using it with real quotes#

Take the bid and ask from your broker's option chain, use the midpoint as the price, enter the exact days to expiry and the current short term interest rate. Compare the result with your platform's IV figure; small differences come from dividends, rates and model choices.

Frequently asked questions#

What is implied volatility?#

The volatility that, when used in an option pricing model, gives the option's current market price; it reflects the market's expectation of future movement.

How is implied volatility calculated?#

By repeatedly trying volatility values in a pricing model such as Black Scholes until the model price matches the market price.

What is a high implied volatility?#

It depends on the asset; compare IV with the asset's own history, for example using IV rank or IV percentile.

Next, price American options with the Binomial Option Pricing Calculator.