The Patek Philippe caliber 240 is one of the most iconic and enduring automatic movements in modern watchmaking. Introduced in 1977, this ultra-thin self-winding movement features a micro-rotor design, allowing it to maintain a slim profile while delivering exceptional accuracy and long-term reliability. It has become a foundational movement for many of Patek Philippe’s most elegant and technically refined watches, from classic dress models to complicated masterpieces.

Overview of the Caliber 240

The caliber 240 was developed during a pivotal era for mechanical watchmaking. Following the rise of quartz technology in the 1970s, Patek Philippe sought to reaffirm the relevance of high-end mechanical engineering with a sleek, automatic movement that could support complications without adding bulk. The result was the 240—an ultra-thin caliber equipped with an off-center 22k gold micro-rotor, embedded within the movement plate rather than mounted on top.

Its introduction enabled Patek Philippe to create ultra-slim watches with automatic winding, helping redefine the modern luxury dress watch.

Technical Characteristics

The 240 is known for its compact size, refined architecture, and excellent finishing. Its core specifications include:

• Type: Automatic with micro-rotor

• Diameter: 27.5 mm

• Height: 2.53 mm

• Frequency: 21,600 vibrations per hour (3 Hz)

• Power reserve: Approximately 48 hours

• Jewels: 27

• Rotor: Off-center, 22k gold, recessed into the movement

• Hairspring: Spiromax® (in later versions)

• Balance: Free-sprung Gyromax® balance wheel

• Finishing: Geneva stripes, perlage, anglage, black-polished screws, and hand-finished bridges

The micro-rotor design reduces thickness without sacrificing winding efficiency, and it leaves more of the movement visible through sapphire casebacks—a feature collectors and enthusiasts appreciate.

Use in Patek Philippe Watches

The 240 has powered a wide range of high-end Patek Philippe references, including:

• Calatrava Ultra-Thin models – such as Ref. 5120, Ref. 5127, and Ref. 5227

• Complications – including annual calendars, dual time zones, and world time watches

• Grand Complications – such as minute repeaters and perpetual calendars, where its slim profile is essential

• Ellipse d’Or – Patek’s iconic oval-shaped model, where thinness is a core design element

Its versatility, thinness, and reliability make the 240 one of Patek Philippe’s most flexible and enduring movements.

Legacy and Importance

The caliber 240 is not just another automatic movement—it’s a symbol of Patek Philippe’s innovation, elegance, and mechanical purity. Over its multi-decade lifespan, the base 240 has evolved into several important variants:

• 240 Q – with perpetual calendar

• 240 PS – with small seconds

• 240 HU – with world time function

• 240 LU – with moonphase

• 240 QP – used in perpetual calendar models like Ref. 3940 and Ref. 5327

Despite its age, the 240 remains in active production and continues to evolve with the integration of modern materials like Silinvar® for better performance and longevity.

Servicing and Longevity

Due to its micro-rotor construction and ultra-thin components, the 240 should be serviced only by qualified professionals—preferably authorized Patek Philippe service centers. When properly maintained every 5–7 years, it remains one of the most reliable automatic calibers in high horology.

Its architecture makes it more delicate than standard rotor movements, but it’s engineered to perform flawlessly for generations when cared for correctly.

Conclusion

The Patek Philippe caliber 240 is a true icon of mechanical refinement. Its elegant micro-rotor design, ultra-thin profile, and technical versatility have made it a cornerstone of Patek Philippe’s success for nearly five decades. Whether in a simple Ellipse or a complex perpetual calendar, the 240 continues to represent the pinnacle of discreet mechanical luxury—a timeless choice for collectors and connoisseurs alike.