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Implied volatility calculator from an option price

The option chain shows a price. Hidden inside it is the market's guess at how wild the next few weeks will be. Type in the price and pull that guess out — as a percent, and as a dollar move by expiry.

Free tool · calls + puts · Black-Scholes · runs in your browser

How it works: the Black-Scholes model turns a volatility into an option price. This calculator runs it backwards. It tries a volatility, prices the option, and keeps narrowing the guess until the model price matches the price you typed. The volatility that matches is the implied volatility: the yearly swing the market is charging for. It then turns that into a dollar move by expiry: stock price × IV × √(days ÷ 365).

What the number is telling you

IV is the price of the option, said as a percent. A 30% IV on a $100 stock says the market is charging for a typical swing of about $30 over a full year. A high IV means the option is expensive. That's good for the seller's premium, and it's also the market warning you that a big move is likely. Both are true at once. More in implied volatility explained and implied vs historical volatility.

Why some prices have no answer

An option can never be worth less than its in-the-money amount, and a call can never cost more than the stock. A price outside those walls can't come from any volatility, so the calculator says so instead of making one up. That usually means a stale quote, a wide bid-ask spread, or a typo. Use the mid price from a live chain. In the wheel strategy, sellers compare IV across strikes and dates on the same stock to see where the premium is rich.

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