Sidoarjo Regency

Sidoarjo Regency (Javanese: ꦑꦧꦸꦥꦠꦺꦤ꧀ꦱꦶꦢꦲꦂꦗ, romanized: Kabupatèn Sidaharja) is a regency in East Java, Indonesia. It is bordered by Surabaya City and Gresik Regency to the north, by Pasuruan Regency to the south, by Mojokerto Regency to the west, and by the Madura Strait to the east. It has a land area of 719.34 km², making it physically the smallest regency in East Java, although it contains many of the southern suburbs of Surabaya and has a high population density. This is particularly true in the northern districts of Waru and Taman, which immediately adjoin the city to the north, and also in the urban area based on Sidoarjo town, which including its suburbs had a combined population of 586,602 at the 1990 Census.

As at the 2010 census, Sidoarjo Regency had a population of 2,191,489 while the 2020 census showed a small decline to 2,033,760, notably in the northern part of the regency immediately bordering Surabaya; the official estimate as at mid-2024 showed an almost unchanged total of 2,027,874 (comprising 1,015,862 males and 1,012,012 females). The entire regency is part of the urban region surrounding Surabaya, known as the 'Gerbangkertosusila' area.