According to several early catalogue descriptions, the Beauvais Missal originally comprised 309 leaves. The Sotheby’s catalogue also tells us that the first recto of the calendar was originally blank. That means that the calendar actually begins – surprisingly – on the verso of folio 1. The contents of the surviving calendar leaves give one month per side and support this contention. The calendar quire, then, seems to have been comprised of three bifolia and one singleton, December on the recto and a blank verso. In this proposed configuration, the two surviving leaves (Feb./March and August/Sept.) comprise a formerly conjoint bifolium.
The Sotheby’s catalogue also mentions that there were fourteen leaves of added prayers at the end; that could be a quire of 14, or perhaps a quire of 8 and a final quire of 6. That leaves 288 leaves uncollated. Assuming that these 288 leaves were bound in quaternions, there would have been 36 more quires of eight. The hypothetical collation of the Beauvais Missal can be expressed as follows:
16+1, 2-378, 3814 (or 388, 396) = 309