Black-Scholes Option Pricing Calculator

Category: Options & Derivatives

Calculate theoretical values and Greeks for European-style options using the Black-Scholes model

Option Parameters

Option Type
$
Current underlying price
$
Option exercise price
Time until option expiration
%
Annual risk-free interest rate
%
Annual dividend yield
%
Annual volatility of underlying
Convert Trading Days to Years
Time to Expiry (Years): 1.00

Option Pricing Results

Option Price
$10.45
Call Option
Intrinsic Value
$0.00
Amount option is in-the-money
Time Value
$10.45
Premium above intrinsic value
Moneyness
At-the-Money
Ratio: 1.00

Option Greeks

Δ
Delta
0.528
Rate of change with respect to underlying price
Γ
Gamma
0.017
Rate of change of Delta with respect to underlying price
Θ
Theta
-0.048
Rate of change with respect to time (per day)
V
Vega
0.391
Rate of change with respect to volatility (per 1% change)
ρ
Rho
0.486
Rate of change with respect to interest rate (per 1% change)

Price Visualization

About the Black-Scholes Model

The Black-Scholes model, developed by Fischer Black, Myron Scholes, and Robert Merton in 1973, is a mathematical model for pricing European-style options. It assumes that the price of the underlying asset follows a geometric Brownian motion with constant volatility.

Black-Scholes Formula

Call Price:
C = S₀e⁻ᵈᵗN(d₁) - Xe⁻ʳᵗN(d₂)
Put Price:
P = Xe⁻ʳᵗN(-d₂) - S₀e⁻ᵈᵗN(-d₁)
Where:
d₁ = [ln(S₀/X) + (r - d + σ²/2)t] / (σ√t)
d₂ = d₁ - σ√t
S₀ Current stock price
X Strike price
t Time to expiration (in years)
r Risk-free interest rate
d Dividend yield
σ Volatility of the underlying
N(x) Cumulative normal distribution function

Key Assumptions

  • European-style options (no early exercise)
  • Efficient markets with no transaction costs or taxes
  • Stock prices follow a lognormal distribution
  • Volatility and risk-free rate are constant over the option's life
  • No arbitrage opportunities exist

Note: The Black-Scholes model has limitations and may not accurately price options in all market conditions, particularly during periods of high volatility or market stress.

Understanding the Greeks

Δ Delta

Measures the rate of change of the option price with respect to changes in the underlying asset's price. Delta ranges from 0 to 1 for calls and -1 to 0 for puts. It represents the equivalent exposure in the underlying asset.

Γ Gamma

Measures the rate of change of Delta with respect to changes in the underlying price. High Gamma means the Delta is highly sensitive to price changes in the underlying asset.

Θ Theta

Measures the rate of change of the option price with respect to time (time decay). Theta is typically negative for both calls and puts, as options lose value as time passes.

V Vega

Measures the rate of change of the option price with respect to changes in volatility. Higher implied volatility generally increases option prices.

ρ Rho

Measures the rate of change of the option price with respect to changes in the risk-free interest rate. Call options generally increase in value when interest rates rise, while put options decrease.

What this calculates

The theoretical price of a European call or put.

Formula
C = S·N(d₁) − K·e^(−rT)·N(d₂), where d₁ = [ln(S/K) + (r + σ²/2)T] ÷ (σ√T) and d₂ = d₁ − σ√T
Worked example
S = 100, K = 100, r = 5%, σ = 20%, T = 1 year gives a call of about 10.45.
When to use it
To value an option and see how the price responds to volatility and time.
Common mistake
It assumes constant volatility and no early exercise. Real options violate both, which is why implied volatility varies by strike.