Audemars Piguet Royal Oak Chronograph 38mm Gets New In-House Calibre 6401
A Long-Awaited Movement Upgrade
Audemars Piguet has addressed one of the most common criticisms of the Royal Oak Selfwinding Chronograph 38mm by equipping it with a brand new in-house movement. The compact and unisex 38mm RO Chronograph, first launched in 2019, now features the new Calibre 6401, replacing the outsourced Frédéric Piguet 1185 (AP Calibre 2385) that had been in use since 1997.
Why the Movement Upgrade Matters
Since 1997, AP had relied on a modified Frédéric Piguet 1185 ébauche – a column-wheel chronograph with vertical clutch, 3Hz frequency, and 40-hour power reserve. While technically competent, the movement was considered antiquated and did not reflect the high-end positioning of the Royal Oak. The new Calibre 6401, developed over five years, addresses these concerns with modern specifications.
Technical Specifications
| Specification | Detail |
|---|---|
| Case Diameter | 38mm |
| Case Thickness | 11.1mm |
| Movement | Calibre 6401 (In-house) |
| Movement Type | Integrated column-wheel chronograph |
| Frequency | 4Hz / 28,800 vph |
| Power Reserve | 55 hours |
| Components | 348 parts, 44 jewels |
| Water Resistance | 50m |
Key Improvements
The new Calibre 6401 brings several significant upgrades:
- Frequency: Increased from 3Hz to 4Hz for improved chronometric performance
- Power Reserve: Extended from 40 to 55 hours
- Vertical Clutch: Patented by AP to reduce components and eliminate unnecessary play
- Sapphire Caseback: New display back reveals the movement's finishing
References and Pricing
| Reference | Material | Dial | Price |
|---|---|---|---|
| 26450ST.OO.1356ST.01 | Stainless Steel | Blue Grande Tapisserie | CHF 34,000 |
| 26450OR.OO.1356OR.01 | 18k Pink Gold | Grey Grande Tapisserie | CHF 66,700 |
| 26450OR.ZZ.1356OR.01 | 18k Pink Gold + Diamond Bezel | Sand Gold Grande Tapisserie | CHF 72,400 |
Design tweaks include a repositioned date window (now centered between 4 and 5 o'clock), reversed chronograph totalizers (minutes at 9, hours at 3), and redesigned small seconds with Arabic numerals at 20, 40, and 60.
FAQ
Q: Why did AP use the Frédéric Piguet 1185 for so long?
A: The FP 1185 was a proven, reliable column-wheel chronograph with a slim profile. However, its 3Hz frequency and 40-hour power reserve became dated by modern standards.
Q: What makes Calibre 6401 special?
A: It's AP's first in-house integrated chronograph movement, featuring a patented vertical clutch system, 4Hz frequency, and 55-hour power reserve – all developed over five years.
Q: Will this movement appear in other Royal Oak models?
A: According to AP, Calibre 6401 will enter the broader Royal Oak collection later in 2026.
Source
Article based on reporting from Monochrome Watches (February 3, 2026).
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