Tonin [ˈtɔnin] is a village in the administrative district of Gmina Sośno, within Sępólno County, Kuyavian-Pomeranian Voivodeship, in north-central Poland. It lies approximately 5 kilometres (3 mi) south of Sośno, 15 km (9 mi) south-east of Sępólno Krajeńskie, and 35 km (22 mi) north-west of Bydgoszcz.