Plattenhardt is a former municipality in the Esslingen district, in Baden-Württemberg, Germany. It was first recorded in year 1269 as Blatinhart. In 1975 it was merged with the municipalities Bernhausen, Bonlanden, Sielmingen and Harthausen to form the new town Filderstadt. Plattenhardt is today a quarter of Filderstadt, formally named Filderstadt-Plattenhardt. It has 8,482 inhabitants and is located 27 km from Stuttgart.