How much dry vermouth is typically used in a Vodka Martini?

In a Vodka Martini, the typical amount of dry vermouth used is indeed quite small, often around 1/8 oz. This small measure allows for the flavor of the vodka to shine through while still providing a hint of herbal complexity from the vermouth. Bartenders often refer to this as a "dry" martini, where the emphasis is placed more on the vodka itself rather than the vermouth, which adds just a whisper of flavor to the drink.

Using 1/16 oz. would create an even drier martini, where the vermouth presence is nearly imperceptible and may not contribute any taste at all. On the other hand, measuring 1/4 oz. or 1/2 oz. would create a drink that leans more toward a standard martini with a more pronounced vermouth flavor, which strays from the intended profile of a Vodka Martini. Therefore, the choice of 1/8 oz. strikes the right balance for this classic cocktail, emphasizing the purity of the vodka while allowing for subtle complexity with the addition of vermouth.