What amount of dry vermouth is used for a "Regular" martini?

In a "Regular" martini, the amount of dry vermouth typically used is indeed 1/4 oz. This measurement strikes a balance between the gin or vodka and the vermouth, allowing the herbal flavors of the vermouth to complement the primary spirit without overpowering it.

A classic martini is generally characterized by its spirit-forward nature, where the base spirit remains the focal point. The addition of 1/4 oz of dry vermouth enhances the drink's complexity while adding a subtle aromatic profile that rounds out the drink.

Choosing this amount is also a nod to traditional recipes, where vermouth serves to add depth rather than diminish the gin or vodka's character. While some variations exist, such as dry martinis with little to no vermouth, the 1/4 oz is widely accepted as a standard for a balanced "Regular" martini.