Kalachinsk is a town located in the Omsk Oblast of Russia. It is situated on the Om River and lies along the busiest segment of the Trans-Siberian Railway, approximately 100 kilometers (62 miles) east of Omsk, which serves as the administrative center of the oblast.
According to census data, the population of the town has shown slight fluctuations over recent decades. The 2010 census recorded a population of 23,556, following figures of 24,247 in 2002 and 25,014 during the 1989 Soviet census.