Guide
The Datejust by Size: 28, 31, 36 and 41, and What Each Number Changes
2,184 Datejusts in this library divide by case size, and the size decides the movement inside, the shape of the reference number and how many variants exist. A guide to reading the family.
The Datejust is one watch in four sizes, and the size is not a cosmetic choice. It decides which movement is inside, what the reference number looks like, how many variants Rolex made, and, in this library, how rare any one of them is. This library holds 2,184 watches across the Datejust collections, and the sizes divide them like this.
| Collection | Case | Movement | Watches here | Base references |
|---|---|---|---|---|
| Lady-Datejust | 28 mm (26 mm before 2015) | 2236 (2235 on the 26) | 428 | 32 |
| Datejust 31 | 31 mm | 2235, then 2236 from 2020 | 1,171 | 45 |
| Datejust 36 | 36 mm | 3135, then 3235 from 2018 | 519 | 26 |
| Datejust 41 | 41 mm | 3235 | 50 | 6 |
| Datejust II | 41 mm, 2009–2016 | 3136 | 16 | 3 |
Size decides the movement
Rolex makes two families of movement, and the 36 mm case is the border between them. Below it, the Lady-Datejust and the Datejust 31 run the 20 mm calibers, the 2235 and its successor the 2236, which the 2236 piece covers. From 36 mm up, the Datejust 36 and 41 run the 28.5 mm calibers, the 3135 and the 3235, compared in the 3135-to-3235 piece.
The two families changed generation at different times, which is why a current Datejust 31 and a current Datejust 36 have different reserves: 55 hours from the 2236, 70 from the 3235. The small movement has the silicon Syloxi hairspring; the large one has Parachrom and the Chronergy escapement. Neither is a lesser version of the other. They are different designs for different amounts of room.
Size decides the reference number
The Rolex convention, set out in the reference-number guide, encodes the size in the first digits and the generation in the count. The current Lady-Datejust is 2791xx, the Datejust 31 is 2782xx, the Datejust 36 is 1262xx, the Datejust 41 is 1263xx; their predecessors were 1791xx, 1782xx, 1162xx and 1163xx. The last two digits before the suffix record the bezel and material, and the suffix after the hyphen records the dial.
The generation changes are the movement changes. 1162xx to 1262xx in 2018 is the 3135 giving way to the 3235; 1791xx to 2791xx in 2015 is the 2235 giving way to the 2236 and the case growing from 26 mm to 28 mm; 1782xx to 2782xx in 2020 is the same movement change for the 31. The Datejust II's 1163xx references became the Datejust 41's 1263xx in 2016, with a slimmer case and the 3235 in place of the 3136.
Size decides how many variants exist
The Datejust 31 is the largest collection in this library at 1,171 watches, more than twice the 36. That is not because more 31s were made; it is because the 31 mm case was offered in more configurations. It has 45 base references against the 36's 26, and each base reference branches into dials: the 178384, 178274 and 178344 alone hold more than fifty variants each. The Lady-Datejust does the same with 32 base references, four of which hold around thirty dials apiece.
The 41 is the opposite. Fifty watches, six base references, and a rarity median of 1: the current Datejust 41 is a young collection in a few configurations, and almost every variant here is one of a family. The variant-families piece explains how those family sizes are built and what they do and do not tell you.
Size decides the materials
Across all 2,184 Datejusts, 1,232 are Rolesor, Rolex's word for steel with a gold bezel and bracelet centres, and only 116 are plain steel. But the mix shifts with the size. The Lady-Datejust's largest group is solid Everose gold, 84 references, with Everose Rolesor a close second. The Datejust 31's largest group is solid yellow gold, 232 references. The Datejust 36's is white Rolesor, steel with a white gold fluted bezel, at 153, and the 36 is also where plain steel is most common. The smaller the case, the more gold in the library.
The bezel follows the same logic. Among the Datejusts here, 761 names carry a fluted bezel, 679 a domed one and 679 a diamond-set one; the diamond bezels concentrate in the 28 mm and 31 mm cases.
Which page to browse
If you know the size you want, the collection pages are the place to start: the Lady-Datejust, the Datejust 31, the Datejust 36 and the Datejust 41. If you know the movement you want, the caliber pages list every watch that carries it. And if you have a reference number, its first three digits will tell you both before you open either.