LONDON—Sotheby's has released details for "Beautiful Inside My Head Forever," its planned auction of new works by Damien Hirst, first announced last month.

The two-day auction, comprising an evening sale on September 15 and morning and afternoon sessions on September 16, will include 223 works with pre-sale estimates ranging from £15,000–20,000 for a number of new drawings to £8–12 million for the monumental installation The Golden Calf. Together the sessions are expected to realize upward of £65 million ($129 million).

The sale is unusual in that the consignor of the works is Hirst himself. Proceeds from four lots will go to charities selected by the artist, and one oil painting, Bill with Shark (est. £200–300,000), will be sold on behalf of the Bill & Melinda Gates Foundation.

None of the works on offer have ever been seen in public before. They will be shown in a 10-day exhibition opening September 5 in Sotheby's London galleries.