Collinas is a comune (municipality) in the Province of Medio Campidano in the Italian region Sardinia, located about 50 kilometres (31 mi) northwest of Cagliari and about 9 kilometres (6 mi) northwest of Sanluri. As of 31 December 2004, it had a population of 954 and an area of 20.8 square kilometres (8.0 mi2).