How Options Are Priced
Written by the MarketWrench team. Examples are worked with the same Black-Scholes model used in our calculators (4% rate, no dividends unless stated) and are reviewed for accuracy before publishing. How we create content.
An option's price can look random at first. Two calls on the same stock can cost $0.66 and $10.70 on the same day. Once you split the price into two parts and know the six things that move it, it starts to make sense.
Price = intrinsic value + extrinsic value
Intrinsic value is what the option would be worth if exercised right now. For a call it is the stock price minus the strike (if positive). For a put it is the strike minus the stock price (if positive). It can never be negative.
Extrinsic value, also called time value, is everything above intrinsic value. It is the price of possibility: the chance that the option becomes more valuable before it expires. At expiration, extrinsic value is zero and the option is worth exactly its intrinsic value.
Hypothetical: XYZ is at $100. A 30-day $95 call costs $6.65. Intrinsic value is $100 − $95 = $5.00. Extrinsic value is $6.65 − $5.00 = $1.65. A 30-day $105 call costs $1.66, and all of it is extrinsic, because it is out of the money.
The six inputs
| Input | If it rises, calls… | If it rises, puts… |
|---|---|---|
| Stock price | gain value | lose value |
| Strike price | are cheaper (higher strikes) | are pricier (higher strikes) |
| Time to expiration | usually gain value | usually gain value |
| Implied volatility | gain value | gain value |
| Interest rate | gain a little | lose a little |
| Dividends | lose value | gain value |
Of these, the only one nobody can look up directly is volatility. That is why traders talk about IV so much: it is the input the market is actually negotiating over. Read what is implied volatility for more.
Why more time and more volatility cost more
An option buyer's loss is capped at the premium, but the gain is open-ended. More time or more volatility widens the range of prices the stock could reach. The extra bad outcomes don't hurt the buyer more (the option just expires worthless either way), while the extra good outcomes help a lot. So a wider range of outcomes is worth more to the buyer, and the seller charges more for it.
Black-Scholes in plain English
The Black-Scholes model is a formula that turns the six inputs into a theoretical price. Roughly, it asks: if the stock moves randomly with this volatility, what is the average payoff of this option at expiration, discounted back to today? It makes simplifying assumptions (steady volatility, no sudden jumps, European-style exercise), so real prices drift from it. It is still the standard reference point. You can run it yourself in our Black-Scholes calculator.
Worked example: one stock, five strikes HYPOTHETICAL
XYZ at $100, 30 days to expiration, IV 30%, rate 4%. Model prices:
| Strike | Call | Call intrinsic | Put | Put intrinsic |
|---|---|---|---|---|
| $90 | $10.70 | $10.00 | $0.40 | $0 |
| $95 | $6.65 | $5.00 | $1.33 | $0 |
| $100 | $3.59 | $0 | $3.26 | $0 |
| $105 | $1.66 | $0 | $6.32 | $5.00 |
| $110 | $0.66 | $0 | $10.29 | $10.00 |
Extrinsic value is largest at the money ($3.59 for the $100 call) and shrinks as you move away in either direction. That is where uncertainty about the outcome is greatest.
Time and volatility in numbers
The same $100 call, still with XYZ at $100: with 90 days left it is worth about $6.41, with 30 days about $3.59, with 7 days about $1.70. Keep 30 days but raise IV from 30% to 45%, and it rises to roughly $5.30. The stock never moved. See theta and time decay for how that value bleeds away.
Bid, ask and the real price
Model prices are theory. In the market you buy at the ask and sell at the bid. The gap, the bid-ask spread, is a real cost. On busy options it may be a few cents, while on thinly traded ones it can be a large share of the price. Our options chain guide shows where to find these numbers.
Common mistakes
- Thinking a cheap OTM option is a bargain. It is cheap because the market thinks it will probably expire worthless.
- Ignoring extrinsic value when buying ITM options. You pay for time that will decay.
- Treating the model price as the "true" price. It is only as good as the IV you feed it.
FAQ
Why is my option losing value when the stock hasn't moved?
Time decay and falling implied volatility both shrink extrinsic value even when the stock is flat.
Is Black-Scholes accurate?
It is a useful approximation. Real markets have jumps and changing volatility, and US stock options can be exercised early.
Which option has the most time value?
Usually the at-the-money option with the longest time to expiration.
Not financial advice
This page is for educational and informational purposes only. It is not financial, investment, tax, or legal advice, and it is not a recommendation to buy or sell any security or to use any strategy. All examples use hypothetical numbers. Options involve risk and are not suitable for everyone. Do your own research and consider talking to a licensed professional before trading.
Read next
What Is Implied Volatility? · Theta and Time Decay · All Learn articles