The rent for an unimproved Baltic Avenue is $4 in the standard Monopoly board game.
Baltic Avenue is one of the two brown properties, along with Mediterranean Avenue. When a player owns Baltic Avenue but has built no houses or hotel, the title deed specifies a base rent of $4. That amount applies when another player lands there and the property is not mortgaged.
Owning the complete brown color group doubles the base rent on unimproved properties, making Baltic Avenue’s rent $8 before any buildings are added. Houses then increase the payment according to the title deed, and a hotel produces the group’s highest listed rent.
The amount is often confused with Baltic Avenue’s purchase price, which is $60, or with Mediterranean Avenue’s base rent, which is $2. The question concerns rent only and assumes the property is active, owned, and without buildings.