Audemars Piguet 26674ST Royal Oak Perpetual Calendar Review

There are Royal Oaks, and there are Royal Oaks, ones that take the iconic reference to the next level. On that next level are references such as this 26674ST, which represents one of the most complicated interpretations of the Royal Oak. It includes a vivid moonphase complication and an ultra-thin self-winding movement: the debut of the new calibre 7138. 

For this new calibre, it’s a strong way to make an entrance. Originally launched in 2025 as an anniversary model, the 26674ST marked 150 years of Audemars Piguet, with much of that time spent mastering the perpetual calendar. With the Royal Oak being the brand’s flagship of sorts, there was no better way to debut a new, self-winding movement, with one in stainless steel and one in an 18KT sand gold case. The new movement, building off of the calibre 7121 with a new module, debuted in a Code 11.59 model as well. 

The pièce de résistance of this movement is what it forgoes. There are no additional pushers to interrupt the shape and flow of that quintessentially angular Royal Oak case. Every function of the perpetual calendar is set entirely via the crown, across four positions, to set the date, month, leap year, and the time itself. This reference has a distinct lack of correctors, which in previous models required tools to set certain functions. As a result, not only does the new perpetual calendar claim greater robustness, but also offers no compromise in water resistance. 

In this stainless steel example, the blue dial seems to change color in the light, featuring a “Grande Tapisserie” that is in keeping with the bold tradition of the Royal Oak. Subdials on the left and right feature plenty of visual depth, with stepped indices for a 24-hour indicator, as well as the month and all-important leap year. At the bottom, a wide moonphase display and the Audemars Piguet text stand out, both visually dominant largely due to this subdial’s simplicity. A transparent caseback showcases the calibre 7138’s gilded and engraved rotor. 

The overall package is a groundbreaking piece of mechanical work, especially in its modest 41mm case size, featuring the patented ultra-thinness of an Audemars Piguet perpetual calendar. Today, the reference 26674ST.OO.1320ST.01 represents genuine progress into what Audemars Piguet does best, and is a fitting way to look forward to the next 150 years of the brand.