The Hourstriker Verdict
The newest members of the Royal Oak Chronograph collection finds the compact 38 mm cases now getting an updated Caliber 2385 automatic movement with a integrated column wheel and a vertical clutch. This is all housed in a very sleek 11.1 mm thick case, even including a display case back. Of the three, the non-diamond set pink gold model sticks out the most to me. While I prefer larger Royal Oak Offshores personally, I can see these upgraded 38 mm Royal Oak Chronographs as extremely important for Audemars Piguet.
— Peter, Editor-in-Chief
Audemars Piguet has formally announced the introduction of a new generation within its Royal Oak Chronograph 38 millimeter collection, marked fundamentally by the integration of an entirely new proprietary movement. This transition represents a significant technical update for the manufacturer, retiring the long-utilized Calibre 2385, which has served as the mechanical foundation for the brand's smaller chronographs since its debut in 1997. The introduction of the new Calibre 6401 across three distinct references signals a shift toward verticalized production for this specific case size, moving away from heavily modified external ebauches toward fully in-house architecture. Historically, the 38 millimeter dimension was reintroduced in 2019 to provide a more compact alternative to the prevailing 41 millimeter models, appealing to purists who prefer dimensions closer to Gérald Genta's original 39 millimeter design from 1972. By incorporating a modern engine into this traditional footprint, the brand effectively addresses long-standing technical critiques regarding the predecessor's power reserve and pusher actuation feel.
The transition to the new movement architecture is accompanied by the notable inclusion of a sapphire crystal exhibition caseback, a feature previously absent from the 38 millimeter Royal Oak Chronograph lineup. This structural alteration requires precise engineering tolerances to maintain the collection's established 50-meter water resistance rating while preventing any increase in overall case thickness. Maintaining the 11.1 millimeter profile was a stated priority for the engineering teams, ensuring the watch retains its established wearability metrics despite the inclusion of a more complex mechanical caliber. The visual transparency allows for direct inspection of the movement's components, which aligns the 38 millimeter models with the visual standards set by the larger 41 millimeter variants within the current catalogue. Consequently, this update homogenizes the internal technology and external presentation across the broader Royal Oak Chronograph family, establishing a unified mechanical baseline.
Courtesy of Audemars Piguet
The Case and Dial
Close inspection of the exterior architecture reveals strict adherence to the traditional multi-part case construction, defined by the signature octagonal bezel secured by eight exposed, hexagonal white gold screws. The case dimensions measure precisely 38 millimeters in diameter with a total thickness of 11.1 millimeters, providing a geometric ratio that balances the visual weight of the complication against the wrist. Surface finishing relies on a high-contrast interplay between rigorous vertical satin brushing across the flat planes of the bezel and case, and highly polished chamfers along the continuous bevels that trace the edges of the components. This finishing technique demands meticulous manual intervention, as the transition between the brushed and polished surfaces must remain perfectly sharp to maintain the case's architectural rigidity. The pushers and crown are executed in matching metals, featuring faceted surfaces that integrate functionally with the sharp angles of the primary case body.
Material selection plays a critical role in the functional and aesthetic presentation of the new collection, utilizing specific alloys engineered for durability and visual stability. The stainless steel utilized in reference 26450ST is a low-carbon alloy chosen for its high pitting resistance, rendering it highly resistant to chloride-induced corrosion from sweat or environmental exposure. Conversely, the 18-carat pink gold models utilize a specific metallurgical mixture that includes copper for color and a small percentage of silver and palladium to stabilize the alloy and prevent oxidation fading over time. Grade 5 titanium, often used in other sports models for weight reduction, is notably absent here, as the manufacturer prioritized the traditional heft and finishing capabilities of gold and steel. The diamond-set reference incorporates 40 brilliant-cut stones set directly into the bezel, requiring precise milling of the gold to ensure the structural integrity of the setting under kinetic stress.
The dial layout has undergone a strict structural reorganization necessitated by the new movement architecture, resulting in enhanced bilateral symmetry across the horizontal axis. Specifically, the minute and hour totalizers have been laterally inverted compared to the previous generation; the minute counter is now positioned at the 9 o'clock index, while the hour counter occupies the 3 o'clock position. The date aperture has been repositioned closer to the central pinion, sitting equidistantly between the 4 o'clock and 5 o'clock applied markers, which improves the overall balance of the negative space on the dial. The primary dial surface features the traditional "Grande Tapisserie" guilloché pattern, a three-dimensional texture created through a complex pantograph engraving process that simultaneously cuts the raised squares and the lozenge-shaped background texture. The subdials are recessed and finished with concentric snailing, providing a distinct optical contrast that aids in the rapid acquisition of chronological data during timing events.
The manufacturer is launching this new generation with three specific color configurations, relying on established chromatic codes within the brand's history. The initial stainless steel reference utilizes the historic "Bleu Nuit, Nuage 50" dial tone, paired with matching blue subdials and 18-carat white gold hands treated with luminescent material. The second reference is constructed entirely from 18-carat pink gold, offset by a dark grey dial with contrasting beige sub-registers and pink gold appliques. The final variant retains the 18-carat pink gold case and is fitted with a sand gold-toned dial and beige counters, utilizing the high refractive index of the diamond-set bezel to amplify the ambient light capture of the exterior casing. The application of luminescent material on the indices and hands across all models ensures high visibility in low-light environments, maintaining the functional utility required of a sports chronograph.
Courtesy of Audemars Piguet
The Movement
The operational core of these new references is the newly developed Calibre 6401, a self-winding mechanical chronograph movement comprising exactly 348 discrete components. Operating at a modern frequency of 4 Hertz, or 28,800 vibrations per hour, the balance wheel provides the necessary temporal resolution for precise chronographic measurement down to one-eighth of a second. The movement measures 27 millimeters in diameter, or 12 lignes, with a total thickness of 5.7 millimeters, dimensions specifically engineered to optimize the internal volume of the 38 millimeter case. This represents the culmination of a five-year internal development program aimed at modernizing the brand's smaller chronographs and eliminating reliance on external supply chains for critical mechanical components. The incorporation of an instant-jump date mechanism further modernizes the user interface, ensuring the date transition occurs instantaneously at midnight rather than dragging slowly across several hours.
Mechanically, Calibre 6401 utilizes an integrated architecture featuring a column wheel mechanism paired with a vertical clutching system, widely considered the most mechanically stable configuration for modern chronographs. The column wheel acts as the central command hub, smoothly coordinating the start, stop, and reset functions through precision-milled pillars that interact with the corresponding actuating levers. Audemars Piguet has implemented a newly patented clutch mechanism designed to simplify the overall architecture, reducing the number of active components to minimize mechanical play and internal friction. The primary functional advantage of the vertical clutch is the elimination of the initial forward or backward jump of the central seconds hand upon actuation, a common kinetic artifact found in traditional lateral clutch designs. Furthermore, this vertical engagement reduces the tactile resistance required to depress the push-pieces, resulting in a more responsive and consistent haptic feedback during operational cycles.
The power generation and storage systems have also been substantially upgraded over the outgoing generation, delivering a guaranteed minimum power reserve of 55 hours when fully wound. This extended autonomy ensures the watch can remain stationary for over two days without requiring manual winding or necessitating a resetting of the time and date functions. The visual presentation of the movement through the new sapphire caseback is characterized by high-level horological finishing techniques consistent with the brand's historical manufacturing standards. An openworked monobloc rotor, constructed from heavy metal to maximize rotational inertia and visibility of the underlying gear train, handles the automatic winding duties. The mainplates and bridges are decorated with uniform Côtes de Genève striping, while the edges of the structural components exhibit manual anglage, featuring highly polished chamfers that catch the light against the matte, straight-grained flanks.
Courtesy of Audemars Piguet
The Strap
The integration of the metallic bracelet into the case remains a critical structural and visual component of the product's design language, requiring exact machining tolerances at the lug junctions. The bracelet links are constructed to taper gradually from the initial case attachment point down to the terminal clasp, reducing the total mass of the metal on the underside of the wrist for ergonomic efficiency. Each link component is secured via internal lateral pins and features a complex dual-finish execution, with strict satin brushing across the top surfaces and highly polished chamfers on the outer edges. The intermediate connecting studs, which provide the articulation necessary for the bracelet to drape cleanly over the wrist profile, are similarly polished on their terminal end-faces.
Securing the bracelet is a proprietary three-blade double-deployant folding clasp, engineered specifically to sit entirely flush against the inner curvature of the links when closed. The clasp is actuated via a dual-button tension-fit mechanism, requiring deliberate and simultaneous lateral pressure to disengage the lock. This mechanical redundancy prevents accidental deployment during active kinetic use, securing the mass of the case safely against the wearer. The inner blades of the deployant are polished and laser-engraved with the manufacturer's operational hallmarks, maintaining the finishing standards present on the exterior components.
Courtesy of Audemars Piguet
Pricing and Availability
The formal introduction of the new Calibre 6401-equipped models marks a definitive restructuring of the 38 millimeter Royal Oak Chronograph product matrix. These initial three references replace their direct predecessors entirely within the active catalog, shifting the baseline technical specifications for all future iterations in this specific size category. The distribution of these specific models will be managed strictly through Audemars Piguet's internal retail network, encompassing both corporate-owned boutiques and authorized AP House locations globally.
Production volumes for these new references remain structurally limited by the manufacturing constraints associated with the new in-house movement and the extensive manual hand-finishing required for the cases, bracelets, and intricate dials. The stainless steel variant positions itself structurally as the entry point into the updated collection, while the solid 18-carat pink gold and diamond-set iterations occupy the upper tiers of the specific pricing hierarchy. Official retail pricing for the specific references 26450ST.OO.1356ST.01, 26450OR.OO.1356OR.01, and 26450OR.ZZ.1356OR.01 has been established centrally by the manufacturer and remains subject to regional taxation levies and international currency fluctuation.
Courtesy of Audemars Piguet
Technical Specifications
Case: Stainless steel or 18-carat pink gold, 38 mm diameter, 11.1 mm thickness, glareproofed sapphire crystal and case back, water resistant to 50 m. Bezel optionally set with 40 brilliant-cut diamonds (~0.92 carats).
Movement: Selfwinding Calibre 6401, integrated column wheel chronograph with vertical clutch, 27 mm diameter, 5.7 mm thickness, 348 parts, 44 jewels, 55-hour minimum power reserve, 4 Hz (28,800 vibrations/hour).
Dial: "Bleu Nuit, Nuage 50" Grande Tapisserie, Grey Grande Tapisserie, or Sand gold-toned Grande Tapisserie, contrasting counters, applied hour-markers and hands with luminescent material.
Strap: Stainless steel or 18-carat pink gold integrated bracelet with three-blade folding clasp.
Price: Upon request
Reference Number: 26450ST.OO.1356ST.01 (Steel), 26450OR.OO.1356OR.01 (Pink Gold), 26450OR.ZZ.1356OR.01 (Pink Gold/Diamonds)
Notes: Features a newly patented clutch mechanism to reduce components and eliminate play. Minute counter repositioned to 9 o'clock and hour counter to 3 o'clock.