The Rolex Caliber 1240 is a manual-winding mechanical movement introduced in the late 1970s to early 1980s, and it is part of Rolex’s 12xx series of compact hand-wound calibers. Specifically designed for ladies’ watches, the 1240 is a time-only movement—simple, elegant, and built to deliver reliable performance within small case dimensions. It continued Rolex’s tradition of offering precision and durability even in its smallest models.

The Caliber 1240 is a refinement over previous hand-wound calibers like the 1210 and 1220, with slight adjustments in finishing and parts optimization to improve serviceability and timekeeping.

Technical Specifications

• Type: Manual-winding

• Functions: Hours, minutes

• Jewels: 17

• Frequency: 21,600 vibrations per hour (vph)

• Power Reserve: Approximately 42 hours

• Chronometer Certified: No (typically marked “Precision”)

• Shock Protection: Incabloc or KIF

• Hacking Seconds: No

• Date Function: No

The 1240 is sized for ladies’ watches, typically housed in 24 mm to 28 mm Oyster or Cellini cases.

Movement Features

While minimalist in complication, the Caliber 1240 maintains the robust standards expected from Rolex movements:

• Three-bridge layout for strength and easy servicing

• Rhodium-plated bridges and plates to resist oxidation and wear

• Flat hairspring with manually adjustable regulator

• Free-sprung balance wheel for stable accuracy

• Improved part tolerances over previous iterations in the series

Its compact dimensions made it ideal for thin, elegant cases while still offering reliable performance for daily use.

Watches Powered by Caliber 1240

The Rolex 1240 was primarily used in:

• Rolex Oyster Precision (manual-wind) ladies’ models

• Rolex Cellini dress watches without complications

• Slim, time-only Rolex references in steel, yellow gold, or two-tone

These watches typically feature:

• Minimalist dials, with baton or Roman numerals

• Manual-wind crowns without screw-down systems (in Cellini)

• Domed acrylic crystals and leather straps or fine bracelets

• Elegant proportions for formal or everyday wear

Service and Reliability

The Caliber 1240, like other Rolex hand-wound movements of its era, is:

• Highly reliable when maintained properly

• Easy to service, with a simple and accessible mechanical structure

• Built with long-term use in mind, even in smaller dimensions

Servicing is recommended every 4 to 6 years, depending on usage and storage conditions.

Collectibility and Appeal

Though not highly sought after by mainstream collectors, the 1240 is appreciated by:

• Vintage Rolex enthusiasts, particularly those focusing on ladies' watches

• Watchmakers, who value its straightforward and robust construction

• Buyers seeking affordable, vintage mechanical Rolex pieces

• Collectors of Rolex Cellini or Oyster Precision models from the 1980s

Its value is enhanced when paired with an original dial, crown, and bracelet in good condition—especially in precious metal cases.

Final Thoughts

The Rolex Caliber 1240 is a simple, reliable manual-wind movement that represents Rolex’s dedication to quality—even in its most compact and elegant timepieces. With no complications, it focuses purely on clean, efficient timekeeping, making it an ideal fit for slim ladies’ watches of the late 20th century. For vintage collectors or those seeking a classic Rolex feel in a small package, the 1240 offers enduring charm, functionality, and mechanical purity.