Implied VolatilityIV
Implied volatility (IV) is the future volatility that the market is pricing into an option; higher IV means more expensive options.
Option prices contain a forecast. The more the market expects an asset to move before expiry, the more an option on it costs — and implied volatility is that expectation, backed out of the option’s price and expressed as an annual percentage. It explains why options get expensive before earnings and cheap afterwards, why an option can lose value even when the stock moves the right way, and what the VIX measures. This entry explains IV in practical terms.
- Category
- Derivatives
- Reading time
- 5 min
- Also called
- IV rank, IV percentile, IV crush
- Updated
Implied volatility in plain words
An option’s premium depends partly on the price volatility of the underlying.1 If traders expect big moves, they pay more for options; working backwards from the price gives the volatility the market is “implying”.
Historical volatility looks backward at what prices did; implied volatility looks forward at what option buyers and sellers expect. The VIX, for example, measures the S&P 500’s expected 30-day volatility implied by option quotes.2 See Volatility.
How to read and use implied volatility, step by step
Find the IV of the option
Platforms show IV for each strike and expiry, as an annualised percentage.
Convert to an expected move
A rough one-standard-deviation move = price × IV × √(days ÷ 365).
Compare with history
IV rank or percentile shows where today’s IV sits relative to the past year.
Check upcoming events
IV usually rises before earnings and other known events and falls afterwards.
Match the strategy
Buying options when IV is high means paying up; selling them when IV is high collects more premium but takes on the risk. See Options.
Remember vega
Vega measures how much an option’s price changes for a one-point change in IV. See Option Greeks.
Worked examples
Example 1 — The expected move
Expected moveA stock trades at $100 and its 30-day options show an IV of 40%.
| √(30 ÷ 365) | ≈ 0.287 |
| Expected 1-SD move | $100 × 0.40 × 0.287 ≈ $11.5 |
| Rough range | ≈ $88.50 to $111.50 |
The options market is pricing roughly a ±11.5% move over 30 days — a statistical estimate, not a promise.
Example 2 — IV crush after earnings
IV crushBefore earnings, a call costs $5.00 with IV at 80%. The stock rises 3% on the news, but IV drops to 35%; the call is now worth $3.60.
| Stock | +3% |
| Call | −28% |
The drop in implied volatility outweighed the small move in the stock’s favour — the classic “IV crush”.
Example 3 — Same option, different IV
PricingTwo identical 30-day at-the-money options on $100 stocks: one with IV 20%, one with IV 60%.
| Rough premium (≈ 0.4 × price × IV × √t) | ≈ $2.30 vs. ≈ $6.90 |
For at-the-money options, premium rises roughly in proportion to implied volatility. Tripling IV roughly triples the price.
Implied vs. historical volatility
Why traders watch implied volatility
Option pricing
IV is the main input that makes options cheap or expensive.
Event risk
Rising IV before an event shows how big a move the market expects.
Market fear
Index IV, such as the VIX, rises sharply in sell-offs. See Volatility.
Strategy choice
High IV favours selling premium; low IV favours buying it — each with its own risks.
Advantages and disadvantages
Advantages
- Shows the market’s forward-looking expectation of movement.
- Converts into an expected move for planning.
- Helps judge whether options are cheap or expensive.
Disadvantages
- Expectations can be wrong; realised moves can be much larger or smaller.
- IV differs by strike and expiry, which complicates comparisons.
- Based on pricing models with simplifying assumptions.
- Can collapse after events, hurting option buyers.
Going deeper
Read as far as you need. Each level builds on the one before it.
IV is a price, not a prediction
Beginner
IV reflects what traders are willing to pay for options. High IV means options are expensive because big moves are expected — not that they will happen.
Skew and term structure
Intermediate
IV is usually different for each strike (skew) and each expiry (term structure). In equity indices, out-of-the-money puts often carry higher IV than calls, reflecting demand for crash protection.
Backing IV out of a model
Advanced
IV is the volatility input that makes a pricing model, such as Black-Scholes, return the option’s market price. Because the model’s assumptions are simplified, IV is best seen as a quoting convention for option prices. See Option Pricing Models.
Common mistakes
Buying options right before earnings without accounting for IV
The stock may need to move more than the expected move just to break even.
Selling options just because IV is high
IV is high for a reason; large moves can happen.
Comparing IV across very different assets
Compare an asset with its own IV history.
Ignoring vega
Changes in IV can outweigh price moves.
Check your understanding
Test yourself before moving on. Each answer comes with an explanation.
Key points to remember
- Implied volatility is the volatility priced into options.
- It is forward-looking; historical volatility is backward-looking.
- Expected move ≈ price × IV × √(days/365).
- IV tends to rise before events and fall after them.
- Higher IV means more expensive options, for buyers and sellers alike.
Frequently asked questions
What is a high implied volatility?
What is IV crush?
Is the VIX implied volatility?
Further learning
- Options
The contracts IV is priced into.
- Volatility
Historical volatility and the VIX.
- Hedging
Why protection costs more when IV is high.
- Average True Range
A backward-looking volatility measure in price units.
Sources
This article is written in our own words. The sources below support the specific facts, rules and figures marked with a number in the text. Links open the original publisher’s page.
- Investor.gov (SEC). An Introduction to Options – Investor Bulletin (opens in a new tab) Checked .
- Cboe Global Markets. VIX FAQs (opens in a new tab) Checked .
Educational content, not financial advice. Examples use hypothetical prices and simplified costs; actual fees, margin rules and regulations vary by broker, market and country. We are not affiliated with any publisher linked above. Last reviewed . Report an error or request a source credit.