How much dry vermouth is used in a standard martini?

In a standard martini, the amount of dry vermouth typically used is often referred to as "one count." This is based on the traditional recipe for a martini, which emphasizes the gin or vodka as the primary spirit while the dry vermouth acts as a complement. The concept of a "count" in bartending generally refers to the pour count from a jigger or measuring device, where one count is approximately 1/4 to 1/2 ounce depending on the pour technique.

Using "one count" allows the drinker to still experience the aromatic qualities and slight flavor of the vermouth without overpowering the drink with it. While preferences may vary among bartenders and cocktail enthusiasts, this amount ensures a balanced martini that highlights its primary spirit while still including the vermouth’s nuances.

Other amounts listed may lead to variations in the balance of flavors, but a "one count" measurement is a recognized standard in crafting a classic martini.