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While Audemars Piguet has been making top-tier timepieces since 1875, it was a model designed by Gerald Genta and introduced in 1972 that became the company’s flagship watch. That watch was the Royal Oak. Not only did the Royal Oak become AP’s bread and butter, but the model also established a whole new genre–the luxury sports watch. Although Audemars Piguet has made countless variations of the Royal Oak over the last five decades, the simpler time/date automatic models are the most popular. Today we take a look at two different generations of the Royal Oak Automatic, the Royal Oak 15300 vs 15400, to see how they compare.

Royal Oak 15300 vs 15400
Audemars Piguet Royal Oak 15300 vs 15400

Audemars Piguet Royal Oak 15300

Audemars Piguet launched the Royal Oak 15300 series in 2005. Just to refresh, the letters that come after AP reference numbers, such as ref. 15300ST, indicate the type of metal used on the watch case.

  • BA – Yellow Gold
  • BC – White Gold
  • ST – Steel
  • OR – Rose Gold
  • PT – Platinum
  • TI – Titanium

The ref. 15300 sports a 39mm case and is, of course, topped with the Royal Oak’s signature eight-sided bezel with the exposed screws.

Audemars Piguet Royal Oak 15400 vs 15300
Note the large AP logo at 12 o’clock on the RO 15300ST dial

Inside the 9.4mm thick case is the in-house Audemars Piguet Caliber 3120 automatic movement, which had made its debut in 2003 in the Jules Audemars collection. Caliber 3120 is notable in AP’s history as it was conceived, developed, and built entirely in-house rather than using Jaeger-LeCoultre base movements as a starting point. Operating at 26,000 beats per hour, Cal. 3120 powers the hour, minute, and seconds hands, a date window, and supplies the watch with 60 hours of power reserve.

Royal Oak 15300 vs. 15400
A pair of Royal Oak 15300OR watches on leather bracelets

The RO ref. 15300 watches are furnished with the famed hobnail-patterned AP “tapisserie” dials, available in white, black, or blue. A distinct trait of the 15300 is the placement of a large AP logo that serves as the 12 o’clock marker.

Audemars Piguet manufactured the Royal Oak 15300 until 2012, available in either stainless steel or 18k rose gold and fitted with metal integrated bracelets or leather straps. There was also a limited edition piece in two-tone steel and rose gold.

Audemars Piguet Royal Oak 15400

Audemars Piguet introduced the Royal Oak 15400 series in 2012 to replace the ref. 15300 generation. The 15400 features a larger case diameter at 41mm along with a slightly thicker profile at 9.8mm. It’s worth noting that AP also released the 37mm ref. 15450 that same year for those looking for a smaller version of the Royal Oak.

Audemars Piguet Royal Oak 15400 vs 15300
18k rose gold Royal Oak 15400OR

In addition to the larger case size, Audemars Piguet also tweaked the tapisserie dial slightly. The Royal Oak 15400 includes a double hash mark at 12 o’clock with a smaller AP logo beneath it. Fans of vintage AP watches will instantly recognize that those double indexes from the original 1972 Royal Oak dial.

What’s more, the date window at 3 o’clock had to move slightly towards the center (due to the larger case but the same movement) and is now accompanied by a small index. Inside the case is the same dependable Caliber 3120, which can be seen via the sapphire crystal caseback.

Caliber 3120
The in-house Caliber 3120 automatic movement can be seen via the sapphire caseback

Yet again, AP made the updated Royal Oak 15400 in rose gold or stainless steel, with bracelets or leather straps. (There was also a limited-edition titanium model equipped with a platinum bezel.) Along with the classic blue, black, and white dials, Audemars Piguet added a gray dial option to the collection in 2017.

Quick Comparison 15300 vs 15400

ReferenceYearsSizeCaliberDial Traits
153002005 – 201239mm3120AP Logo at 12
154002012 – 201941mm3120Double hashmark at 12
Index next to date window

The Royal Oak ref. 15400 was in production until 2019 when it was ultimately replaced by the brand new Royal Oak ref. 15500 series. Announced at SIHH 2019, the 15500 now has a new movement, refreshed dial design, and a slightly thicker case.

Arguably one of the most popular luxury sports watches ever made, the Royal Oak model is instantly recognizable regardless of the production era thanks to its bold design and distinctive silhouette.

Written by

Celine Simon

Celine is a freelance luxury watch writer who has enjoyed working in the horology industry for over ten years. Like many of the high-end timepieces she writes about, she comes from Switzerland—the heart of fine watchmaking. From Singapore to Montreal to Geneva to Dubai, Celine has lived all over the world but now calls Southern California home.