Leioa is a municipality in Biscay, Basque Country, in northern Spain. It is located south of Getxo and Berango delimitating east and south with Erandio, Portugalete and Sestao. Today it is part of the Bilbao conurbation. Its population in 2019 was 31,795. Leioa has an area of 8.36 square kilometres (3.23 sq mi). The Udondo river constitutes the eastern limit of the municipality.