Barangay Nag-Iba I

Classified as a small barangay, Barangay Nag-Iba I is one of the administrative divisions of City of Calapan in Oriental Mindoro, MIMAROPA Region, Philippines.

According to the 2020 Philippine census, Barangay Nag-Iba I had a population of 989. This made it the 48th largest of 62 barangays in City of Calapan by population, placing it among the smaller barangays of the city. Residents of Barangay Nag-Iba I accounted for approximately 0.68% of the total population of City of Calapan, which stood at 145,786 in the same census year.

The barangay recorded 947 residents in the 2015 intercensal count and 989 residents in the 2020 Census — a net change of +4.4%, consistent with a growing settlement. Barangay Nag-Iba I is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

City of Calapan is a city comprising 62 barangays, and serves as the governing unit directly responsible for local services in Barangay Nag-Iba I, including public health, sanitation, peace and order, and civil registration. Within the wider province of Oriental Mindoro, which contains 426 barangays across its component cities and municipalities, Barangay Nag-Iba I ranks 347th by 2020 population. Oriental Mindoro is classified as a 1st by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Like every Philippine barangay, Barangay Nag-Iba I is led by an elected Punong Barangay (barangay captain) supported by seven Sangguniang Barangay members (kagawads), an SK Chairperson, a Barangay Secretary, and a Barangay Treasurer. The next Barangay and Sangguniang Kabataan Elections (BSKE) are scheduled for Monday, November 2, 2026, with officials serving four-year terms under Republic Act No. 12232.