Serdang Bedagai Regency is a regency on the east coast of North Sumatra Province of Indonesia, facing Malaysia, with 95 km of coastline and covering an area of 1,904.37 square kilometres, divided into seventeen districts (kecamatan), in turn subdivided into 243 villages. Its administrative centre is the town of Sei Rampah. The regency surrounds the independent city of Tebing Tinggi, and also contains a district (kecamatan) by the same name (Tebing Tinggi District surrounds the city on its west side, while Tebing Syahbandar District surrounds the city on its east side). The name “Serdang Bedagai” was derived from the two Sultanates which formerly existed in the Region; they were Serdang Sultanate and Padang Bedagai Sultanate. The population was 592,922 at the 2010 Census, while the 2020 Census produced a total of 657,490; the official estimate as at mid 2023 was 685,074.

To the north is the Malacca Straits, to the west is Deli Serdang Regency (surrounding Medan), to the south and southeast is Simalungun Regency, and to the east are the Buaya River and Ular River bordering Batubara Regency, which was formed in 2006 from the western part of the Asahan Regency.

The Serdang Bedagai Regency is divided administratively into seventeen districts (kecamatan), tabulated below with their areas and their populations at the 2010 Census and the 2020 Census, together with the official estimates as at mid 2023. The table also includes the locations of the district administrative centres, the numbers of administrative villages in each district (totaling 237 rural desa and 6 urban kelurahan), and its post code.

Kode Wilayah	Name of District (kecamatan)	Area in km	Pop'n Census 2010	Pop'n Census 2020	Pop'n Estimate mid 2023	Admin centre	No. of villages	Post code
12.18.10	Kotarih	76.14	7,975	9,169	9,576	Kotarih	11	20982
12.18.11	Silinda	56.74	8,332	9,514	10,119	Silinda	9	20983
12.18.17	Bintang Bayu	95.59	10,581	12,511	12,747	Bitang Bayu	19	20984
12.18.09	Dolok Masihul	243.48	48,241	52,705	55,518	Pekan Dolok Masihul	28	20991
12.18.12	Serbajabi	50.69	19,560	21,759	22,218	Serbajabi	10	20995
12.18.08	Sipispis	145.26	31,617	33,826	35,082	Sipispis	20	20992
12.18.07	Dolok Merawan	120.60	17,029	17,976	19,147	Dolok Merawan	17	20993
12.18.13	Tebing Tinggi	182.29	40,253	41,162	41,681	Tebing Tinggi	14	20999
12.18.16	Tebing Syahbandar	120.30	32,191	33,585	33,792	Paya Pasir	10	20998
12.18.06	Bandar Khalipah	116.00	24,774	25,857	26,742	Bandar Khakipah	5	20994
12.18.05	Tanjung Beringin	74.17	36,864	42,142	44,730	Tanjung Beringin	8	20996
12.18.04	Sei Rampah	198.90	63,379	71,366	75,061	Sei Rampah	17	20995
12.18.15	Sei Bamban	72.26	42,791	46,043	47,282	Sei Bamban	10	20995
12.18.03	Teluk Mengkudu (Mengkudu Bay)	66.91	41,118	48,334	50,906	Sialang Buah	12	20997
12.18.02	Perbaungan	111.62	99,936	112,153	116,506	Simpang III Pekan	28	20985
12.18.14	Pegajahan	93.12	26,859	30,206	32,016	Pegajahan	13	20986
12.18.01	Pantai Cermin	80.30	42,883	49,182	51,951	Pantai Cermin	12	20987
	Totals	1,904.37	594,383	657,490	685,074		243

Notes: (a) including one kelurahan (Pekan Dolok Masihul). (b) comprising four kelurahan (Batang Terap, Melati I, Simpang Tiga Pekan and Tualang) and 24 desa. (c) including one kelurahan (Melati Kebun).

• Official website

3°22′00″N 99°02′00″E / 3.3667°N 99.0333°E / 3.3667; 99.0333