How much Bourbon is typically used in an Old Fashion cocktail?

In an Old Fashioned cocktail, the standard amount of bourbon used is generally 1 and 1/2 ounces. This measurement strikes a balance, allowing the bourbon to provide the foundational flavor of the cocktail while still allowing room for the added ingredients such as sugar, bitters, and a twist of citrus peel. Using this specific amount helps to prevent the drink from becoming overly diluted or weak, while still maintaining the classic profile that is characteristic of an Old Fashioned.

The other options may vary from certain bartender preferences or specific recipes, but the widely accepted standard in most cocktail cultures leans towards 1 and 1/2 ounces for bourbon, ensuring a well-rounded and flavorful drink.