Sifnos is part of the Western Cyclades, near Kimolos (10 nautical miles), Serifos (12 nautical miles), Paros (14 nautical miles), and Milos (20 nautical miles); it's 75 nautical miles from Piraeus. Shaped like a slightly elongated oval, it reaches 18 kilometers at its longest point on the north-south axis and 8 kilometers at its widest on the east-west axis. The island covers an area of 74 sq. kilometers, with a total shoreline of 28 nautical miles. In antiquity the island was known as Akis.

Sifnos's terrain is slightly rugged, rising to 680 meters at its highest peak, Profitis Ilias or Ai Niyias. Its coast is riddled with pretty coves with sand beaches, both open and sheltered as at Kamares, Platis Yialos, Vathi, Faros, Vlyho or Glyfo, and Fykiada. The uninhabited islet of Kitriani, where the 10th-11th-century church of Panayia Kitriani is located, sits just off Platis Yialos on the southeastern coast. The island has a population of 2,000 who engage in agricultural, stockbreeding, fishing, and ceramics - a craft for which the island is renowned. A large number of males are employed in the merchant marine and tourism also occupies a large segment of the population.

Local products include honey, wine, cheese, capers, figs, almond sweets, bourekia, almond cookies, bread rings, pastelli (nut and honey bars), honey pie, and, of course, ceramics and weaving. Sifnos is administered under the Milos Eparchy and the Cyclades Prefecture. The settlements at Apollonia and Artemonas, divided in 1914, have been reunited since 1999 under a single Municipality of Sifnos.