A Black-Scholes Calculator is a tool used to estimate the theoretical price of European-style options. The Black-Scholes model, developed by economists Fischer Black, Myron Scholes, and Robert Merton in the early 1970s, is a mathematical formula used to determine the fair market value of options, particularly stock options.

The Black-Scholes model is primarily used for pricing two types of options:

1. Call Options: These give the holder the right, but not the obligation, to buy a specific asset (usually a stock) at a predetermined price (strike price) before a specific date (expiration date).

2. Put Options: These give the holder the right, but not the obligation, to sell a specific asset (usually a stock) at a predetermined price (strike price) before a specific date (expiration date).

The key inputs for the Black-Scholes model are as follows:

1. Current Stock Price (S): The market price of the underlying asset (e.g., the stock).

2. Strike Price (K): The predetermined price at which the option holder can buy (for call options) or sell (for put options) the underlying asset.

3. Time to Expiration (T): The time remaining until the option’s expiration date, usually expressed in years.

4. Volatility (σ): The measure of how much the stock price is expected to fluctuate over the option’s remaining time. It is usually expressed as an annualized percentage.

5. Risk-Free Interest Rate (r): The interest rate for a risk-free investment with a maturity equal to the option’s time to expiration. This is typically based on government bond yields.

6. Dividend Yield (q) (for call options only): The dividend paid by the underlying asset. This is relevant for call options because dividends can reduce the stock price.

A Black-Scholes Calculator allows you to input these parameters, and it will compute the estimated option price (C or P) based on the Black-Scholes formula. It’s important to note that this model has some assumptions, such as constant volatility and interest rates, which may not hold true in the real world. Therefore, it’s used as a theoretical framework and not as the sole basis for trading or investment decisions. Traders and investors often use the Black-Scholes model in conjunction with other analyses and tools.