A novel maize variety designated PH18F6 and seed, plants and plant parts thereof. Methods for producing a maize plant that comprise crossing maize variety PH18F6 with another maize plant. Methods for producing a maize plant containing in its genetic material one or more traits introgressed into PH18F6 through backcross conversion and/or transformation, and to the maize seed, plant and plant part produced thereby. Hybrid maize seed, plant or plant part produced by crossing the variety PH18F6 or a locus conversion of PH18F6 with another maize variety.