What this calculator does
Black-Scholes option price works out theoretical price of a European call and put option. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulad1 = [ln(S/K) + (r − q + σ²/2)T] / (σ√T); d2 = d1 − σ√T; Call = S·e^(−qT)·N(d1) − K·e^(−rT)·N(d2); Put = K·e^(−rT)·N(−d2) − S·e^(−qT)·N(−d1)
The inputs explained
| Field | What to enter |
|---|---|
| Current share price ($) | A number, measured in your currency. Starts at 100. |
| Strike price ($) | A number, measured in your currency. Starts at 100. |
| Risk-free interest rate (%) | A number, measured in %. Starts at 5. |
| Dividend yield (%) | A number, measured in %. Starts at 0. |
| Volatility (annualised) (%) | A number, measured in %. Starts at 20. |
| Time to expiry (years) | A number, measured in years. Starts at 1. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with current share price
Every other input is held at the calculator’s starting values while current share price varies. Select any row to load that scenario into the calculator.