The river originates at the lake Pyhäjärvi in Tammela and joins the river Kokemäenjoki in Huittinen.
[1] There is a 54-metre (177 ft) difference in elevation between the source and the mouth of the river, which is 114 kilometres (71 mi) long.
The river drains a catchment area of 3,140 square kilometres (1,210 sq mi).
The river has several dams at Forssa, Jokioinen and Loimaa.
[2] The Loimijoki river runs through the most fertile lands of Finland making its water relatively muddy.