What is the balanced ratio of dry to sweet vermouth in a Perfect Manhattan?

The balanced ratio of dry to sweet vermouth in a Perfect Manhattan is equal parts of each, or one part dry vermouth and one part sweet vermouth. This cocktail variation offers a harmonious blend of the herbal and slightly bitter flavor profile from the dry vermouth with the sweet, smooth characteristics of the sweet vermouth.

Using this balanced ratio provides a unique style of the Manhattan that maintains the cocktail's traditional essence while allowing the different vermouth flavors to complement rather than overpower each other. This can enhance the overall drinking experience, making it distinct and enjoyable for those who appreciate a more balanced flavor profile in their cocktail.