Kalachinsk (Кала́чинск in Russian) is a town in Omsk Oblast, 100km east of Omsk, population approx 25,000. It is located on the Om River along the busiest segment of the Trans-Siberian Railway, after its southern and northern branches meet in Omsk.

Kalachinsk is frequently referred to as Kalachiki. In the Soviet days of restricted commerce, it had acquired regional fame for its week-end tolkuchka . Fueled by visitors arriving by elektrichkas , the open-air flea market bustled with a life of its own, seemingly defying the communist realities.