Karczewizna [kart͡ʂɛˈvizna] is a village in the administrative district of Gmina Łochów, within Węgrów County, Masovian Voivodeship, in east-central Poland. It lies approximately 7 kilometres (4 mi) south-east of Łochów, 20 km (12 mi) north-west of Węgrów, and 62 km (39 mi) north-east of Warsaw.