[mikeyouse]

It’s still used as an input into illiquid 409a valuations.

[nknealk]

It’s also frequently used to price stock options given to employees at publicly traded companies.

[dumah]

Black-Scholes assumes constant volatility and cannot compute option prices without a volatility input.

This volatility is backed out of nearby options prices, often using the formula for European options.

There isn’t any purely theoretical option price because an assumption depends on observed prices.