The western lakeshore lies 17 kilometers (11 mi) to the east of the Kazakhstan–Russia border.

[4] Bolshoy Bagan lies in the Baraba Lowland, West Siberian Plain.

The lake is shallow and has an elongated hourglass shape roughly oriented from northwest to southeast.

[5] It is the largest of a group of scattered lakes located in a treeless, slightly swampy area, to the east of Krasnovishnevoye, west of Kuznetsovka, and south of Ivanovka.

[6] In certain seasons Bolshoy Bagan displays an intense red color.