 It is 135 km long, and has a basin area of 1348 km².Most of its length is in the department of Moselle, except for the part between Aulnois-sur-Seille and Cheminot, which is in Meurthe-et-Moselle.The Seille also forms the border between Moselle and Meurthe-et-Moselle from Chambrey to Aulnois-sur-Seille.