The regency covers a land area of 2,487.99 square kilometres and according to the 2010 census had a population of 289,708;[2] the 2020 Census showed a population of 360,531,[3] while the official estimate for mid 2023 was 368,834.

Apart from the southern portion of Nias Island, the regency also includes the smaller Batu Islands (Pulau Pulau Batu) to the south, lying between Nias and Siberut; these islands occupy nearly half of the land area of the Regency, but have just 9% of its population.

The table also includes the locations of the district administrative centres, the number of administrative villages in each district (a total of 459 classed as rural desa and 2 classed as urban kelurahan), and its postal code.

The thirteen new districts on Nias Island itself are Hilisalawa'ahe, O'o'u, Onohazumba, Ulususua, Ulunoyo, Huruna, Luahagundre Maniomolo, Onolalu, Boronadu, Sidua'ori, Somambawa, Ulu Idanotae, and Idanotae.

South Nias Regency is a paradise for surfers with four surfing beaches: