Detail of a relief showing Sneferu wearing the white robe of the Sed-festival, from his funerary temple of Dahshur and now on display at the Egyptian Museum
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. Snefru, 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. Since there are many periods in Snefru's reigns for which Egyptologists have few dates—only the years of the 2nd, 7th, 8th, 12th, 13th, 14th, 15th, 16th, 17th, 18th, 23rd and 24th count are known for Sneferu before one considers the years after his cattle counts—this pharaoh is most likely to have had a reign in excess of 30 years to manage to build three pyramids in his long rule but not 48 years since the cattle count was not regularly biannual during his kingship. (There are fewer years after the count dates known for Sneferu compared to year of the count or census dates.)