Audemars Piguet Royal Oak Chronograph 38mm Gets New In-House Calibre 6401 - 2026
Audemars Piguet Upgrades Royal Oak Chronograph 38mm with Revolutionary In-House Calibre 6401
Audemars Piguet has delivered a long-awaited upgrade to the Royal Oak Selfwinding Chronograph 38mm, replacing the decades-old outsourced movement with an all-new in-house calibre. Released on February 3, 2026, this significant technical evolution addresses collector feedback while maintaining the compact, unisex appeal that made the 38mm Royal Oak Chronograph a modern success since its 2019 launch.
Bidding Farewell to the FP 1185 Legacy
According to Monochrome Watches, the Royal Oak 38mm chronograph had relied on the Frédéric Piguet 1185 ébauche since 1997, rebranded as the AP Calibre 2385. While this column-wheel chronograph was slim (5.5mm) and reliable, its 3Hz frequency and 40-hour power reserve were increasingly seen as dated for a watch at AP's price point. The new Calibre 6401, developed over five years, addresses every criticism while delivering modern performance.
Technical Specifications
| Specification | Calibre 6401 (New) | Calibre 2385 (Old) |
|---|---|---|
| Frequency | 4Hz (28,800 vph) | 3Hz (21,600 vph) |
| Power Reserve | 55 hours | 40 hours |
| Movement Thickness | 5.7mm | 5.5mm |
| Movement Diameter | 27mm | 26.2mm |
| Components | 348 parts, 44 jewels | 280 parts, 21 jewels |
| Caseback | Sapphire crystal | Solid |
Integrated Column-Wheel Chronograph
The Calibre 6401 features AP's patented integrated column-wheel chronograph with vertical clutch system. This design reduces the number of components and eliminates unnecessary play, resulting in a robust, reliable, and responsive chronograph that requires less pressure to activate the pushers. The movement showcases refined finishing including Côtes de Genève on bridges, polished bevels, and an openworked rotor visible through the new sapphire crystal caseback.
Design Refinements
Alongside the movement upgrade, AP has introduced several subtle design improvements. The date window has been repositioned to sit exactly midway between 4 and 5 o'clock indices, creating a more symmetrical dial appearance. The chronograph counters have been reversed, with minutes now at 9 o'clock and hours at 3 o'clock. The small seconds counter features new Arabic numerals at 20, 40, and 60 for improved legibility.
Available References and Pricing
Three references launch the new collection:
- Stainless Steel (26450ST): CHF 34,000 - Blue "Grande Tapisserie" dial with blue counters
- Pink Gold (26450OR): CHF 66,700 - Grey "Grande Tapisserie" dial with silver counters
- Pink Gold with Diamond Bezel (26450OR.ZZ): CHF 72,400 - Sand gold-toned dial with beige counters
Market Significance
This upgrade addresses one of the most common criticisms of the Royal Oak 38mm chronograph, bringing the compact model in line with AP's larger chronograph offerings. The new sapphire caseback allows owners to admire the beautifully finished movement, while the improved specifications justify the watch's luxury positioning. The 38mm size continues to appeal to both men and women seeking a more restrained alternative to the larger Royal Oak Offshore chronographs.
Frequently Asked Questions
Q: What is the difference between the Calibre 6401 and the 4400 series?
A: The 6401 is a smaller, integrated chronograph designed for the 38mm case, while the 4400 series (4401/4404) are larger flyback chronographs for 41-43mm cases. Both feature AP's column wheel and vertical clutch technology.
Q: Is the case thickness significantly different?
A: The 38mm case thickness increased marginally from 11mm to 11.1mm, a negligible difference that preserves the watch's sleek profile.
Q: Can I still purchase models with the old movement?
A: Previous 38mm chronographs with the Calibre 2385 are only available through pre-owned markets or remaining dealer stock. All new production uses the Calibre 6401.
Source: According to Monochrome Watches
Explore our guides on chronograph calibre comparisons and Royal Oak collection guide.