Implied Volatility Calculator

How to Use This Calculator

1. Enter the Stock Price, Strike Price, Time to Expiry, and Risk-Free Rate.
2. Enter the Market Option Price — the actual bid/ask midpoint from your broker.
3. Select Call or Put.
4. The calculator solves for IV using Newton-Raphson iteration and shows convergence details.
5. Switch to Professional to compare IV vs historical volatility and compute IV Rank.

Formula

Example

Frequently Asked Questions

• What is implied volatility? ▼
  Implied volatility (IV) is the market's expectation of future volatility, extracted from an option's market price. Unlike historical volatility (which looks backward), IV reflects what the market is "implying" about future price swings.
• How is IV calculated? ▼
  IV cannot be solved algebraically from Black-Scholes — it is solved iteratively. The Newton-Raphson method starts with an initial sigma guess and refines it until the theoretical option price matches the market price, typically converging in under 20 iterations.
• What is IV Rank (IVR)? ▼
  IV Rank measures where the current IV sits relative to its 52-week range: IVR = (Current IV − 52w Low) / (52w High − 52w Low) × 100. IVR of 80 means IV is near the top of its annual range — a signal that options are expensive.
• What is a volatility smile? ▼
  In theory Black-Scholes assumes constant volatility across strikes. In practice, OTM puts often have higher IV than ATM options, creating a "skew." When both OTM puts and OTM calls have higher IV than ATM, the shape is called a "smile."
• When is IV considered high or low? ▼
  There is no universal threshold — it depends on the stock and market regime. IV Rank (IVR) contextualizes IV relative to its own history: IVR > 50 is generally elevated; IVR > 80 is very high. Many traders sell premium when IVR > 50.

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