Sneferu (snfr-wj "He has perfected me", from Ḥr-nb-mꜣꜥt-snfr-wj "Horus, Lord of Maat, has perfected me", also read Snefru or Snofru), well known under his Hellenized name Soris (Σῶρις by Manetho), was the founding pharaoh of the Fourth Dynasty of Egypt during the Old Kingdom. Estimates of his reign vary, with for instance The Oxford History of Ancient Egypt suggesting a reign from around 2613 to 2589 BC, a reign of 24 years, while Rolf Krauss suggests a 30-year reign, and Rainer Stadelmann a 48-year reign. He built at least three pyramids that survive to this day and introduced major innovations in the design and construction of pyramids.
The 24-year Turin Canon figure for Sneferu's reign is considered today to be an underestimate since this king's highest-known date is an inscription discovered at the Red Pyramid of Dahshur and mentioning Sneferu's 24th cattle count, corresponding to at least 24 full years.Miroslav Verner, Archaeological Remarks on the 4th and 5th Dynasty Chronology", Archiv Orientální'''. vol. 69, Praha 2001, p. 367 Sneferu, however, was known to have a minimum of at least three years after the cattle count dates: his years after the 10th, the 13th and the 18th count are attested at his Meidum pyramid. This would mean that Sneferu ruled Egypt a minimum of 27 full years.
However, in the Palermo Stone, recto 6 at the bottom of the fragment shows the year of the 7th count of Sneferu while recto 7 on the same following row shows the year of the 8th count of Sneferu. Significantly, there is a previous mostly intact column for Sneferu in recto 5 which also mentions events in this king's reign in a specific year but does not mention the previous (6th) year. This column must, therefore, be dated to the year after the 6th count of Sneferu. Hence, Sneferu's reign would be a minimum of 28 years.