Few watches mix sport and fine watchmaking as perfectly as the Royal Oak Perpetual Calendar. Created by Audemars Piguet's bold team, it combines Gérald Genta's famous 1972 design with one of the most advanced features in watchmaking — the perpetual calendar.
A perpetual calendar is a special watch that can keep track of the day, date, month, leap years, and moon phases all by itself for many years without needing to be fixed. Audemars Piguet's version is even cooler because it also shows the week number around the edge of the dial, showing how amazing its design and mechanics are.
Collectors love the Royal Oak QP because it mixes perfect timekeeping, beautiful details, and a look you can recognize anywhere. It's a fancy watch that looks great whether you're wearing a T-shirt or a tuxedo.
The 2025 Update: Calibre 7138 & Ref. 26674 (Steel & Sand Gold)
In 2025, Audemars Piguet made their watches easier to use with the new Calibre 7138. It started a new kind of perpetual calendar that's thinner, stronger, and simpler to handle.
You no longer need tiny buttons on the case to fix the date or moon phase. Now, one crown controls everything — the day, date, month, and moon. This makes the watch easier to wear every day and means it doesn't need service as often. The new movement ticks 28,800 times per hour and lasts about 55 hours on one wind, all while staying only about 4.1 mm thick.
The debut references, 26674ST (steel) and 26674SG (sand gold), come with small but noticeable updates. They have sharper edges on the case, a smoother bracelet that fits better, and a slightly new dial pattern called "Grande Tapisserie." The new sand gold color looks like a mix between pink and yellow gold, giving it a warm and modern look.
Movement Lineage: 5134 vs. 7138 vs. 5133
Over the past decade, AP's perpetual calendars have evolved dramatically. Here's how the three major calibres compare:
- Calibre 5134 (2015–2024): This watch was the main model for the modern 41 mm Royal Oak Perpetual Calendar. It could run for about 40 hours when fully wound and ticked 19,800 times every hour. Its design had four small dials on the face, giving it the clean and smart look the Royal Oak is known for.
- Calibre 7138 (2025): The evolution of the 5134, with a slimmer profile, higher frequency, improved accuracy, and crown-only operation. It's a watchmaker's dream and a collector's daily companion.
- Calibre 5133 (2018): The record-breaking movement inside the RD#2, measuring just 2.89 mm thick and allowing the 26586IP Ultra-Thin model to achieve a staggering 6.2 mm case height. It was a technological milestone — though produced in very limited quantities.
Together, they show how AP went from making classic perpetual calendars to creating modern watches that are comfortable and made for today's collectors.
Iconic References & Materials at a Glance
From tough ceramic to super-thin platinum, the Royal Oak Perpetual Calendar comes in many special styles. Here are some of the most popular versions, each with its own story.
- Ref. 26579CE – Black Ceramic: The modern grail. A full-ceramic case and bracelet paired with AP's blue "Grande Tapisserie" dial. Lightweight, scratchproof, and endlessly wearable.
- Ref. 26579CB – White Ceramic: A collector's favorite for its ghostly tone and contrasting blue accents. Minimalist yet statement-making.
- Ref. 26674SG – Sand Gold (2025): Introduces the 7138 calibre in a warm, soft-gold hue exclusive to AP — poised to be the next icon.
- Ref. 26674ST – Steel (2025): The purest, most versatile form. Combines everyday resilience with the 2025 movement's refined usability.
- Ref. 26586IP – RD#2 Ultra-Thin: A platinum-titanium hybrid housing the ultra-slim calibre 5133; the thinnest automatic perpetual calendar ever made.
- Ref. 26585XT – 150th Anniversary Openworked: Crafted in titanium and bulk metallic glass (BMG), showcasing a skeletonized calibre 5135 — a breathtaking fusion of tradition and innovation.
- "John Mayer Crystal Sky": The unofficial farewell to the 5134, featuring a shimmering dial reminiscent of the night sky.
- "Travis Scott Cactus Jack": A brown ceramic limited edition blending streetwear culture and horological excellence — a true crossover collectible.
How the Perpetual Calendar Works (and How to Set It)
A perpetual calendar is a special watch that keeps track of time almost perfectly. It knows which months have 30 or 31 days and even adds the extra day in leap years all by itself. It will stay accurate until the year 2100, when people will need to adjust the calendar by hand.
Inside, a tiny mechanical "memory" encodes the four-year leap cycle. The moonphase display, precise to ~122 years, charts the lunar cycle in poetic detail.
To set one, especially on older models like the 5134, patience is key:
- Always adjust when the watch is running and avoid changes between 8 PM and 4 AM, when gears are engaged.
- Use the special buttons (on older models) or the single crown (on the Calibre 7138) to move the dates forward one at a time.
- Once it's set, keep the watch running by wearing it or using a winder so it stays in perfect time.
Ownership Realities: Size, Thickness, Water Resistance, Service
The Royal Oak Perpetual Calendar wears as refined as it reads on paper. The modern 41 mm case is AP's sweet spot — elegant yet assertive — with slight differences depending on the movement and case material.
- Thickness: Around 9.5 mm for standard ceramic/steel models, down to 6.2 mm for the ultra-thin RD#2.
- Water Resistance: Rated at 20 meters, meaning it's splash-resistant but not suited for swimming. Collectors treat it as a dress complication — not a diver.
- Servicing: Expect full maintenance every 5–7 years through AP or trusted specialists. Perpetuals are complex, so servicing costs reflect their craftsmanship.
- Bracelet/Comfort: The integrated bracelet remains one of the finest in watchmaking — fluid, balanced, and unmistakably AP.
When it comes to price, the Royal Oak Perpetual Calendar is one of the most expensive luxury watches you can buy. The value depends on things like the material, how rare it is, and its condition, but many versions sell for well over one hundred thousand dollars, especially the rare ceramic or limited edition models.
Should You Buy One? (Who It's For)
This isn't just a watch — it's a statement of engineering art and restraint.
Buy It if You Value
- The fusion of modern sport design and centuries-old horology
- A mechanical calendar you'll likely never need to correct
- AP's iconic case and bracelet architecture
Consider Your Lifestyle
- Steel or Ceramic suits daily wearers who appreciate durability and stealth luxury.
- Gold or Platinum suits collectors who prefer timeless presence and weight.
- Ultra-Thin (RD#2) rewards purists chasing innovation and record-setting craftsmanship.
It's not for everyone, but for the right collector, few watches feel this special. Simply put, yes, it's worth it. Just be sure to buy from experts who know how to check, care for, and service it the right way.
Final Thoughts
The Royal Oak Perpetual Calendar is one of Audemars Piguet's greatest creations. It blends history, beautiful design, and new technology all in one watch. The new Calibre 7138 makes it even better for today's collectors, keeping it stylish and comfortable to wear.
While many things come and go, this watch stays timeless and truly shows what makes Audemars Piguet special.
Explore available Royal Oak collection or contact our team to source your next masterpiece today.
