Audemars Piguet Unveils the New Royal Oak Chronograph 38mm with In-House Calibre 4401

Audemars Piguet has officially updated its 38mm Royal Oak Chronograph collection, finally integrating the sophisticated in-house Calibre 4401 movement into the mid-size case. This release marks a significant technical leap for the iconic "Jumbo" sibling, offering improved proportions and a flyback function.

By: AXL Media

Published: Feb 14, 2026, 11:41 AM EST

Source: Watches by SJX

For years, the 38mm version of the Audemars Piguet Royal Oak Chronograph was powered by the Calibre 2385, a movement based on the Frederic Piguet 1185. While reliable, enthusiasts have long awaited the integration of AP’s own in-house integrated chronograph movement. With the debut of the Ref. 26450, the wait is over. The new model finally adopts the Calibre 4401, the same high-performance engine found in the larger 41mm models and the Code 11.59 collection.

The shift to the Calibre 4401 is more than just a branding update; it brings a suite of technical upgrades to the 38mm silhouette. This integrated, self-winding chronograph features a column wheel and a vertical clutch system, ensuring a smooth start/stop sequence without the "jump" often seen in lesser movements. Notably, it includes a flyback function, allowing the wearer to reset the chronograph without stopping it first. The power reserve has also been boosted to a robust 70 hours.

Visually, the Ref. 26450 retains the DNA that has made the Royal Oak a legend since 1972. The case has been subtly refined to accommodate the new movement while maintaining a thickness that remains wearable and elegant. The dial features the signature “Grande Tapisserie” pattern, available in a range of classic Audemars Piguet hues, including the iconic Bleu Nuit, Nuage 50.

The sub-dial layout has been slightly adjusted to reflect the new architecture of the movement, offering better symmetry and legibility. For the first time in the 38mm size, owners can now view the beautifully finished gold oscillating weight and movement through a sapphire crystal caseback.

By bringing the in-house movement to the 38mm case, Audemars Piguet is addressing a major segment of the market that prefers more moderate dimensions without sacrificing technical prestige. The new Royal Oak Chronograph 38mm is expected to be a highly sought-after piece for collectors who find the 41mm models too imposing but demand the pinnacle of modern horology.