Patek Philippe Cubitus 5840P: The First Grand Complication in the Boldest Case Patek Has Ever Made

Description

When Patek Philippe launched the Cubitus in 2023, it was a statement: the house of Stern was willing to go square. The design divided opinion — boldly proportioned at 45mm, with a dial architecture built around horizontal lines that echoed the Nautilus's porthole grammar but in an entirely different register. Three years later, Patek answers any lingering scepticism with the 5840P-001: the Cubitus's first grand complication.

The Perpetual Calendar Skeleton in 950 platinum is more than an escalation — it is the watch that establishes the Cubitus as a genuine collection with technical depth. Patek has developed the Calibre 28-28 Q SQU specifically for this case, a square-shaped skeletonised automatic movement whose footprint mirrors the case geometry precisely. The result is a watch where case, dial, and movement speak a single visual language, unified by the horizontal-grid skeleton pattern that runs through all three layers simultaneously.

At 10mm thick for a full perpetual calendar with moonphase, seconds, and 24-hour indicator, the 5840P is a watch for collectors who want technical seriousness without display-piece proportions. The baguette diamond set into the platinum bezel at 6 o'clock — Patek's signature detail for platinum-cased grandes complications — is the only concession to adornment. Everything else is movement.

Design

The 5840P occupies a 45mm platinum case just 10mm thick — remarkable for a full perpetual calendar. The case follows the Cubitus's signature silhouette: a square cushion shape with integrated lugs and the characteristic horizontal-bar pattern engraved across the bezel and case flanks. The platinum surfaces are finished with a combination of brushed and polished treatments, keeping visual weight in check despite the case's generous footprint.

The skeletonised dial is the watch's defining achievement. The Calibre 28-28 Q SQU's square-footprint movement is visible through apertures whose horizontal striping exactly matches the case's horizontal grid — when dial and movement are superimposed, the patterns align perfectly, creating a visual depth that reads as one coherent plane rather than a dial floating above a movement. Calendar sub-registers for day, date, month, and leap year are arranged around the periphery in Patek's restrained typographic style. A single large moonphase disc — visible as a graphic circle rather than a hemispherical window — completes one full 29.53-day rotation, making it one of the most dramatic moonphase presentations in the Patek line. The strap is navy blue composite with a fabric-weave pattern and cream stitching, secured by a platinum folding clasp.

Specifications

Reference: 5840P-001
Case diameter: 45mm
Case thickness: 10mm
Case material: 950 Platinum
Bezel: Platinum, baguette-cut diamond set at 6 o'clock
Crystal: Sapphire, anti-reflective coating
Water resistance: 30m
Strap: Navy blue composite fabric-pattern, cream stitching, platinum folding clasp
Movement: Calibre 28-28 Q SQU — in-house automatic
Movement architecture: Square-shaped skeletonised, derived from Calibre 240 Q
Movement dimensions: 31.5mm × 31.5mm × 5.04mm
Parts / Jewels: 313 parts, 27 jewels
Rotor: 22K gold Gyromax micro-rotor
Balance spring: Spiromax (silicon)
Frequency: 21,600 vph (3 Hz)
Power reserve: 38–48 hours
Complications: Perpetual calendar (date, day, month, leap year), moonphase, sweep seconds, 24-hour indicator
Price: CHF 150,000 (approx. US$187,547 / €176,700)

What's Exciting

The Calibre 28-28 Q SQU is the technical centrepiece, and its most important attribute is its shape. Patek's perpetual calendar movements have historically been round — the Calibre 240 Q that underpins most of the perpetual calendar line is a 30mm disc. The new 28-28 Q SQU is square, 31.5 × 31.5mm, developed specifically so that the Cubitus case could host a perpetual calendar without any of the proportional compromises that come from fitting a circular movement in a square case. The square calibre means the dial's horizontal skeleton pattern and the movement's bridges can align perfectly — an architectural achievement as much as a horological one.

At 10mm total case thickness, the 5840P is thinner than most round perpetual calendars on the market. The Gyromax rotor and Spiromax silicon balance spring are both in-house Patek technologies that guarantee long-term precision without the need for shock protection components that would add height. For collectors, this watch signals that the Cubitus is not a one-generation experiment — Patek has invested in dedicated movement architecture, which means the Cubitus platform will support new complications for decades.

History

Patek Philippe was founded in Geneva in 1839, initially as a partnership between Antoni Patek and Adrien Philippe. Philippe invented the keyless winding mechanism that became standard across the industry; Patek's name gave the maison its commercial foundation. The Stern family, who have owned Patek since 1932, have guided it through the quartz crisis, the rise of the collector market, and the explosion of the auction scene — during which Patek's complicated pieces consistently achieved the highest prices in watchmaking history.

The Cubitus was introduced in 2023 as the third member of Patek's integrated-bracelet sports watch family, alongside the Nautilus (1976, Gerald Genta) and the Aquanaut (1997). Where the Nautilus is round-cornered and the Aquanaut is cushion-shaped, the Cubitus is emphatically square — a deliberate aesthetic departure under Thierry Stern's watch. The 5840P-001 is the first Cubitus grand complication, arriving three years after launch, and it elevates the collection from design statement to serious horological platform.