Fontanet is an unincorporated census-designated place in central Nevins Township, Vigo County, in the U.S. state of Indiana. It lies along Baldwin St., northeast of the city of Terre Haute, the county seat of Vigo County. Although Fontanet is unincorporated, it has a post office, with the ZIP Code of 47851. As of the 2020 census, Fontanet had a population of 347.