The Cubitus was introduced in October 2024 as Patek Philippe's first new watch collection in twenty-five years — a significant institutional statement from a manufacture that has historically been the most deliberate and least trend-responsive of the major Swiss houses. Its square case with rounded corners, its horizontal line embossed dial, its integrated composite strap, and its distinctly contemporary character represented a clear signal from Thierry Stern's fourth-generation stewardship: Patek Philippe was prepared to address the tastes of a newer collecting generation with the same seriousness it brings to the perpetual calendar chronograph and the minute repeater. The 5840P-001, introduced at Watches & Wonders 2026, is the Cubitus collection's first Grand Complication — a perpetual calendar skeleton reference that deploys within the collection's newest format a complication whose development required the creation of an entirely new calibre, designed square to match the case, whose movement architecture and dial architecture share the same structural logic. It is the most technically demanding watch Patek Philippe has yet produced in the Cubitus line, and it makes the case for the collection's seriousness more convincingly than any number of simpler references could.
The case is 950 platinum, measuring 45 millimeters on the diagonal — the square case's dimension measured corner to corner, the format established with the first Cubitus references and maintained across the collection's development. At 10 millimeters in height, the case is remarkably slim for a platinum watch carrying a perpetual calendar and moonphase: the Calibre 28-28 Q SQU's architectural innovations are essential to this slimness, as discussed below. The case architecture combines alternating polished and vertically satin-brushed surfaces — the brushed surfaces on the case flanks and the main case body providing the contemporary, technical quality that the Cubitus's sporting orientation suggests, the polished surfaces on the bezel facets and case transitions providing the formal precision that a Patek Philippe platinum case requires. At 6 o'clock on the bezel, a baguette-cut diamond is set into the surface — a detail present on all Patek Philippe watches in platinum, the single stone serving as both a material marker of the metal's status and a geometric accent whose rectangular form harmonizes specifically with the Cubitus case's own square geometry. The two-part case construction with lateral lugs retains the established Cubitus architecture, and the crown at three o'clock manages setting functions for the perpetual calendar's displays.
The dial is the 5840P-001's most immediately compelling feature, and it requires a specific kind of description because it is not, in the conventional sense, a dial at all. The openworked dial consists of the Calibre 28-28 Q SQU's own mainplate and bridges — the structural elements of the movement itself — finished to serve simultaneously as the movement's mechanical components and as the watch's visible face. Superimposed over the movement's openwork structure are horizontal strips of blue-finished material, laser-cut to follow the same horizontal line pattern that characterizes the embossed dials of the Cubitus's standard references and the Nautilus before it. These blue strips create two simultaneous visual effects: they maintain the Cubitus's characteristic horizontal motif across the visible dial surface, providing design continuity with the collection's other references, and they allow the movement's mechanical structure to read through the spaces between the strips, the blue lines and the visible movement existing in the same visual plane and creating what Patek Philippe describes as a "subtle depth effect." The result is a dial of unusual visual complexity: from a short distance it reads as a blue dial with horizontal lines; at close range it reveals the mechanical structure visible through and between the blue strips, the balance wheel's oscillation visible through the openings, the bridges' finishing apparent as architectural detail rather than as a movement casually glimpsed through a display back.
The movement is the all-new Calibre 28-28 Q SQU — a designation that captures the essential design decision that makes this watch's technical achievement significant. The "28-28" refers to the movement's dimensions: 28.5 millimeters by 28.5 millimeters, a square movement designed to occupy the Cubitus case's own square internal volume rather than the conventional round or partially round movement that would require a round movement fitted within a square case. Developing a square perpetual calendar movement is not simply a matter of redistributing existing round-calibre components — it requires rearchitecting the gear train, the perpetual calendar mechanism, and the winding system to conform to a square plate rather than the circular geometry that centuries of watchmaking have optimized. The movement is 5.04 millimeters in height, 313 parts, 27 jewels. All components — plate, bridges, wheel plates, balance wheel, and the 22-karat gold micro-rotor that provides automatic winding — share the same rhodium-plated finish, a monochrome approach that gives the visible movement its unity of appearance and prevents the usual contrast between gold-colored bridges and steel-colored plates from competing with the blue horizontal strips above. The micro-rotor, integrated at bridge level in the manner of the Calibre 240, allows the movement's total height to remain within the case's slender profile. The perpetual calendar mechanism employs the 48-month cam system typical of the Calibre 240Q series — the cam's circumference divided into 48 segments representing the four-year leap year cycle, different grooves on the cam's rim programming the different monthly lengths — providing the same level of precision and correction-free operation across the full four-year cycle.
The display layout distributes the perpetual calendar's information across three symmetrically positioned subdials in the arrangement that recalls the Nautilus 5740's established layout: the day of the week and 24-hour indication at nine o'clock, the month and leap year indication at three o'clock, and the date with moonphase at six o'clock. The calendar hands within each subdial are white, their contrast against the blue ground providing legibility through the openwork's visual complexity. The moonphase display at six o'clock is the 5840P-001's most technically innovative single dial element — Patek Philippe describes it as a "high-definition" moon, metallized and laser-engraved rather than the conventional printed or painted disc used in most moonphase watches. The laser engraving produces the lunar surface's relief detail at a resolution that conventional dial printing cannot achieve, and the metallization provides a reflective quality that gives the depicted moon a dimensional, almost photographic presence within its aperture. This is the first large-scale moonphase presentation within the current Cubitus collection, and its execution sets a new standard for the display within the Patek Philippe production.
Applied white gold hour markers with white luminescent coating occupy the primary hour positions around the openworked dial's outer ring, and white gold rounded-baton hands with the same luminescent coating provide the primary time indication. The luminescent coating ensures legibility in low light conditions — a practical priority in a watch whose openwork architecture, for all its visual richness, creates a more visually complex reading environment than a conventional solid dial provides. White gold hands against the blue-and-openwork ground are visible precisely because of the luminescent coating's function in reducing the visual complexity of the background relative to the hands.
The navy blue composite strap with fabric pattern and contrasting cream stitching continues the Cubitus collection's established approach of positioning the watch as a sports-adjacent complicated piece rather than a formal dress complicated piece. The navy blue of the strap is continuous with the blue of the dial's horizontal strips, the color providing material cohesion between case and strap that the composite's different texture and the dial's different material nonetheless support rather than undermine. The platinum fold-over clasp with three independent safety catches provides the security appropriate to a watch of the 5840P-001's value, the three catches operating as redundant locking mechanisms against accidental opening.
The 5840P-001 represents the most direct statement Patek Philippe has yet made about the Cubitus collection's long-term ambitions. The collection launched in 2024 with time-and-date references; it expanded in 2025 with precious metal variants; in 2026 it receives its first Grand Complication, and that complication is not a straightforward deployment of existing calibre architecture into a new case but the creation of an entirely new movement designed from the ground up to occupy a square space. This investment — the engineering resources required to develop the Calibre 28-28 Q SQU, the manufacturing challenges of producing a square perpetual calendar at this level of quality, the integration of a new moonphase technology, all within a movement whose total height remains under the slimness target demanded by the case — is the clearest possible signal that the Cubitus is not an experiment but a commitment. The 5840P-001 is what a new Patek Philippe collection looks like when it grows into its own Grand Complication.
