arking a technical milestone in the Royal Oak’s evolution, the movement debuts on three distinctive references in stainless steel and pink gold. Each timepiece features a sapphire caseback – a first for a Royal Oak Chronograph in 38 mm – revealing the refined architecture and finishing of the calibre within. This represents both an aesthetic and technical leap forward for the Royal Oak 38 mm line, retaining the model’s signature proportions while propelling the Chronograph into the future.

Developed entirely in-house over five years, Calibre 6401 marks a new chapter in Audemars Piguet’s chronograph legacy and a significant milestone in the evolution of the Royal Oak Chronograph 38 mm line. It replaces the longstanding Calibre 2385, a movement introduced in 1997 that quickly became a cornerstone of the Manufacture’s offerings for nearly three decades.

Like its predecessor, Calibre 6401 is an integrated column wheel chronograph with a vertical clutch system. Audemars Piguet has patented the clutch mechanism, simplifying its architecture to reduce the number of components and eliminate unnecessary play. The result is a robust, reliable and responsive chronograph, requiring less pressure to activate the push-pieces to offer an enhanced user experience.

Delivering a 55-hour power reserve, the movement also features a simple instant-jump date and a reimagined counter layout designed for improved legibility. Calibre 6401 will also enter the Royal Oak Offshore collection later this year, ensuring continuity and coherence across the brand’s offering.

The introduction of Calibre 6401 brings subtle yet significant aesthetic evolutions to the Royal Oak 38 mm line. Most notably, the sapphire caseback now reveals the intricacies of the movement, inviting a direct connection between the wearer and the heart of the timepiece. Visible from the back of the watch, an openworked monobloc rotor reveals the elegant finishings of the selfwinding movement, including the Côtes de Genève motif and alternating satin brushing and polished chamfers.

The dial layout has also been adjusted for greater symmetry and readability, with the date aperture now more centrally positioned between the 4 o’clock and 5 o’clock hour-markers. In contrast to Calibre 2385, the minute counter now sits at 9 o’clock and the hour counter at 3 o’clock, ensuring better visual balance.

Preserving the proportions of its predecessor, the watch retains its 11 mm thickness, accommodating the new movement without compromising wearability or size. Each of the three new references showcases these refinements through distinct stylistic lenses. The iconic “Bleu Nuit, Nuage 50” Grande Tapisserie dial is paired with a stainless-steel case and bracelet in tribute to the original aesthetic codes of the Royal Oak for timeless sports-chic sophistication. This model retains the same aesthetic as the current version, with the addition of the sapphire caseback and more centred date opening between hour markers.

An 18-carat pink gold version featuring a dark grey dial with beige counters embraces subtle contrasts. The interplay between warm gold and cool grey heightens depth and legibility, with pink gold hands and hour- markers adding a sophisticated and harmonious touch.

Finally, a third reference combines an 18-carat pink gold case with a sand gold-toned dial, beige counters and a diamond-set bezel. The latter offers glamourous refinement to the soft-toned palette, for a luminous expression of elegance and technical mastery.

Since its debut in 1972, the Royal Oak has disrupted the landscape of fine watchmaking. Conceived by Gérald Genta, it introduced the concept of the high-end steel sports watch, transforming it from a utilitarian tool into a symbol of status and style. The Royal Oak Chronograph, introduced on the 25^th anniversary of the Royal Oak, added a layer of dynamism and complexity to the collection, expanding its appeal to a new generation of enthusiasts.

Over the decades, the Royal Oak Chronograph has undergone several evolutions. The case was reimagined in 2008 (Ref. 26300) to mirror the three-part construction of the Royal Oak Offshore collection. In 2012, the line was up sized to 41 mm (Ref. 26320), introducing a more classic dial layout and refined proportions. A bold redesign followed five years later (Ref. 26331) featuring enlarged subdials, a repositioned date aperture, and a more expressive visual language.

In 2019, the 38 mm Royal Oak Chronograph (Ref. 26315) marked a return to a size that’s closer “Jumbo” dimensions of the original Royal Oak, offering a more compact and balanced alternative to the larger chronograph models. Its symmetric subdial design echoed the original Ref. 25860, introduced in 1997 in a 39 mm case, while subtle updates to the dial and bracelet ensured modern relevance.

Arriving last year in celebration of Audemars Piguet’s 150th anniversary, the Royal Oak Extra-Thin Selfwinding Flying Tourbillon Chronograph RD#5 in 39 mm (Ref. 26545, Calibre 8100) elevated the chronograph for the modern era. Remarkably thin, its discreet push-pieces – inspired by smartphone haptics – offer a smoother and more intuitive experience for wearers.

From Genta’s original sketch to today’s in-house chronograph, the Royal Oak continues to evolve while staying true to its disruptive roots. Bringing renewed sense of purpose to the Royal Oak Chronograph 38 mm line, the latest calibre stands as a testament to Audemars Piguet’s enduring commitment to watchmaking excellence.