Barangay San Isidro Sur

Barangay San Isidro Sur is a mid-sized barangay in the City of Sto. Tomas, located in the province of Batangas, in the CALABARZON region of the Philippines.

According to the 2020 Philippine census, Barangay San Isidro Sur had a population of 3,377. This made it the 19th largest of 30 barangays in City of Sto. Tomas by population, placing it in the middle tier of the city. Residents of Barangay San Isidro Sur accounted for approximately 1.55% of the total population of City of Sto. Tomas, which stood at 218,500 in the same census year.

The barangay recorded 2,653 residents in the 2015 intercensal count and 3,377 residents in the 2020 Census — a net change of +27.3%, consistent with a growing settlement. Barangay San Isidro Sur is officially classified as urban, reflecting the density and built-up character of the area.

City of Sto. Tomas is a city comprising 30 barangays, and serves as the governing unit directly responsible for local services in Barangay San Isidro Sur, including public health, sanitation, peace and order, and civil registration. Within the wider province of Batangas, which contains 1,078 barangays across its component cities and municipalities, Barangay San Isidro Sur ranks 246th by 2020 population. Batangas is classified as a 1st by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Barangay San Isidro Sur is governed by an elected Sangguniang Barangay composed of a Punong Barangay and seven kagawads, with the Sangguniang Kabataan representing the youth. The next BSKE, set for Monday, November 2, 2026, will elect officials to four-year terms as provided under Republic Act No. 12232.