Patek Philippe Introduces The Cubitus Perpetual Calendar Skeleton Ref. 5840P-001
With the introduction of the Cubitus collection in late 2024, Patek Philippe established a new design language built around a square case with rounded corners and an integrated, sporty-leaning aesthetic. The initial trio of large-format references focused on time-and-date functionality. Then, smaller models in precious metals arrived in 2025. At Watches and Wonders 2026, the brand expands the concept with the collection’s first grand complication. Meet the Cubitus Perpetual Calendar Skeleton ref. 5840P-001.
The new model combines the Cubitus case architecture with a fully skeletonized perpetual calendar movement developed specifically for the square format. Rather than adapting an existing round caliber without modification, Patek Philippe designed this one to match the geometry of the case, resulting in a layout that emphasizes symmetry and visibility. The watch also introduces a monochrome openworked aesthetic within the Cubitus line, along with a large moonphase display not previously seen in the regular-production collection.
Rundown: Cubitus Perpetual Calendar Skeleton ref. 5840P-001
The Cubitus Perpetual Calendar Skeleton features a 45mm by 10mm platinum case. It retains the two-part construction with lateral lugs seen on earlier large Cubitus references. Alternating polished and vertically satin-brushed surfaces define the square silhouette. In good Patek tradition, a diamond set at 6 o’clock signals the use of platinum, but here, it’s a baguette-cut stone. Despite the movement’s complexity, the overall profile remains relatively slim.
The openworked dial follows the linear motif used across the Cubitus collection, with laser-cut strips aligned with the movement architecture. Blue PVD treatment and horizontal brushing add contrast, while applied white gold hour markers and baton hands with luminescent coating maintain legibility against the skeletonized background. Additional thin white gold hands indicate the calendar functions.
Patek Philippe caliber 28-28 Q SQU
Inside is the newly developed caliber 28-28 Q SQU, a square-shaped skeletonized movement derived from the architecture of the caliber 240 Q. The openworked construction exposes the perpetual calendar mechanism. It displays hours, minutes, and small seconds, along with the date, day, month, leap year cycle, and moon phases.
The movement comprises 313 components and uses the familiar 48-month cam system typical of the 240-series perpetual calendars. It allows automatic adjustment for varying month lengths across a four-year cycle. The visual treatment is largely monochromatic. Rhodium-plated components include the bridges, plates, and micro-rotor, punctuated by heat-blued screws and a blue Calatrava cross.
A large single-moon display replaces the traditional dual-moon disk. The mechanism completes one rotation every 29.53 days and uses layered mineral glass disks to create depth. Engraved stars and blue varnish form the background, while a separate laser-structured moon disk reproduces surface details. This approach expands on a concept previously seen in limited anniversary models but appears here in regular production for the first time.
First impressions
The Patek Philippe ref. 5840P-001 positions the Cubitus line firmly in high-complication territory. Its square skeletonized movement underscores the collection’s geometric identity, while the monochrome finishing and large moon display distinguish it from earlier Cubitus models. At the same time, the use of platinum, a perpetual calendar, and a micro-rotor movement aligns the watch with established themes within the brand’s broader catalog. The result is a technically ambitious addition that extends the Cubitus family.
The watch is delivered on a navy-blue Cordura strap with a textile pattern and contrasting cream stitching. It closes with a platinum folding clasp featuring three independent catches and engraving referencing the Cubitus collection.
The Cubitus Perpetual Calendar Skeleton ref. 5840P-001 retails for €176,700 / US$187,547 / CHF 150,000. Let us know your thoughts on this latest addition to the Cubitus family in the comments section below.
Check out more of our Watches and Wonders 2026 coverage here.
