Berteștii de Jos is a commune situated in Brăila County within the Muntenia region of Romania. The administrative area is composed of four primary villages: Berteștii de Jos, Berteștii de Sus, Gura Călmățui, and Spiru Haret.
Historically, the commune's territory was larger as it formerly included the villages of Gura Gârluței and Nicolești. These two locations are currently noted as being depopulated.