Plainfield, IN -- U.S. town in Indiana Population (2000): 18396 Housing Units (2000): 7449 Land area (2000): 17.981247 sq. miles (46.571213 sq. km) Water area (2000): 0.047493 sq. miles (0.123006 sq. km) Total area (2000): 18.028740 sq. miles (46.694219 sq. km) FIPS code: 60246 Located within: Indiana (IN), FIPS 18 Location: 39.697471 N, 86.384672 W ZIP Codes (1990): Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Plainfield, IN Plainfield