Lopburi is on the east side of the Chao Phraya River valley, between the Lopburi River and Pa Sak Rivers. Thirty percent of the area of the province, including most of Tha Wung district, the southwestern parts of Mueang Lopburi and Ban Mi districts are a very low alluvial plain. The other 70 percent is mixed plains and hills, with the Phetchabun Mountains forming the eastern boundary of the province towards the Khorat Plateau.