Gaj [ɡai̯] is a village in the administrative district of Gmina Biskupiec, within Nowe Miasto County, Warmian-Masurian Voivodeship, in northern Poland. It lies approximately 5 kilometres (3 mi) south-east of Biskupiec, 15 km (10 mi) west of Nowe Miasto Lubawskie, and 80 km (50 mi) south-west of the regional capital Olsztyn.