The Audemars Piguet Royal Oak 15500ST and 15510ST are two generations of the same 41 mm steel Royal Oak Selfwinding: both run the in-house calibre 4302 with 70 hours of power reserve in a near-identical case, and the 15510ST (2022) is the anniversary-year update of the 15500ST (2019). The real jump is one generation earlier, from the 15400ST to the 15500ST, where the movement changed. This guide sets all three side by side, explains what separates the 15500ST from the 15510ST, and helps you decide which to source. Bizak & Co. is a sourcing desk, so each watch below is found to order; the Royal Oak collection lists the configurations we can seek.
Last reviewed on October 28, 2026 by Filip Biczak. Sources: Audemars Piguet, Royal Oak collection. Details vary by dial and production year, so treat the table as a guide and check the exact unit.
What are the differences between the 15400ST, 15500ST and 15510ST?
The 15400ST has the older calibre 3120, while the 15500ST and 15510ST share the newer calibre 4302. The table lists the points that are consistent across Audemars Piguet's published specifications and our earlier single-reference guides.
| 15400ST | 15500ST | 15510ST | |
|---|---|---|---|
| Years | 2012 to 2019 | 2019 to 2022 | 2022 onward |
| Case | 41 mm steel, about 9.8 mm thick | 41 mm steel, about 10.4 mm thick | 41 mm steel, about 10.4 mm thick |
| Movement | Calibre 3120, 3 Hz, about 60 h | Calibre 4302, 4 Hz, 70 h | Calibre 4302, 4 Hz, 70 h |
| Calibre diameter | 26.6 mm | 32 mm | 32 mm |
| Water resistance | 50 m | 50 m | 50 m |
| Rotor | Standard | Standard | Standard; a "50 years" rotor on 2022 pieces |
| Bracelet | Integrated steel, folding clasp | Integrated steel, folding clasp | Integrated steel, folding clasp |
What changed from the 15500ST to the 15510ST?
Very little mechanically: the 15510ST kept the 41 mm case and the calibre 4302, and its changes are cosmetic. It arrived in 2022 for the Royal Oak's 50th anniversary, and the 2022 pieces carry a commemorative "50 years" oscillating weight visible through the caseback. The dial was also revised; ask for close photographs of the dial and caseback of the specific watch. Reported bracelet and case-thickness differences are small enough that they should not drive the decision. In practice the two are close siblings, and the choice usually comes down to dial colour, condition and the price asked. Our 15510ST guide and 15500ST guide cover each watch in depth.
What changed from the 15400ST to the 15500ST?
The movement changed: the 15500ST replaced the 3 Hz calibre 3120 (about 26.6 mm across) with the larger 4 Hz calibre 4302 (32 mm), lifting power reserve from about 60 to 70 hours. Both calibres have a quickset date, set from the crown in the same way. The case kept the same 41 mm diameter and eight-screw octagonal bezel, and grew slightly thicker to house the new calibre. If you want the modern movement, the 15500ST is the lowest-generation Royal Oak 41 mm that has it. The 15400ST remains the value route into a 41 mm steel Royal Oak and is marginally slimmer on the wrist, but its warranty period will have lapsed.
Which is better to buy, the 15500ST or 15510ST?
The better buy is the one in the best condition on the dial you want, since the movement is identical. Use this as a shortcut:
- Choose the 15500ST if you want the same calibre 4302 and the 2019 to 2022 dial design, and a pre-owned example with a good case that has not been over-polished.
- Choose the 15510ST if you prefer the current dial, want the newest production, or want a 2022 piece with the anniversary rotor.
- Choose the 15400ST if budget matters more than the newer movement and you accept an expired warranty.
Whatever you pick, condition, full set and unpolished case finishing matter more than the reference suffix.
What about the 15450ST and the 15550ST?
These are the 37 mm equivalents: the 15450ST is the earlier 37 mm Royal Oak Selfwinding and the 15550ST is its 2022 successor, mirroring the 15400ST to 15510ST progression in the smaller size. Buyers with smaller wrists often compare them against the 41 mm references above. Browse the Royal Oak collection for both sizes, and note that 37 mm and 41 mm watches are different cases, not simply different dials. If you are weighing the slimmer 39 mm Extra-Thin instead, our Royal Oak Jumbo 15202 vs 16202 comparison explains the same 2022 generation change there.
What should you check before buying either watch?
Verify the full reference, the warranty card serial against the caseback, the bezel screws, the case bevels and the bracelet link count. A polished case with rounded bevels is the most common compromise on a pre-owned Royal Oak. Ask for photographs of the caseback so the rotor matches the stated year. If you are looking beyond steel, the wider Audemars Piguet collection and the sportier Royal Oak Offshore collection show what else we can source.
Quick answers
Is the 15510ST the same as the 15500ST?
Mechanically almost, yes. Both are 41 mm steel watches running calibre 4302 with 70 hours of power reserve. The 15510ST arrived in 2022 with a revised dial, and 2022 pieces carry a "50 years" rotor.
Which movement does the 15500ST use?
The in-house calibre 4302, a selfwinding movement running at 4 Hz with 70 hours of power reserve, the same calibre as the 15510ST.
What is the difference between the 15400ST and the 15500ST?
The 15400ST uses calibre 3120 (3 Hz, about 60 hours). The 15500ST uses the larger calibre 4302 (4 Hz, 70 hours). Both have a quickset date and both are 41 mm.
Is the 15500ST discontinued?
Audemars Piguet replaced it with the 15510ST in 2022, so new production now follows the 15510ST. Pre-owned and unworn 15500ST examples can still be sourced.
Does Bizak & Co. keep these watches in stock?
No. Bizak & Co. sources each watch to order, confirming the exact unit, photographs and final price with you before you commit.
Related reading: Audemars Piguet Royal Oak Silver and White Dial and Royal Oak Sizes Compared.
Request a Royal Oak 15500ST or 15510ST sourcing quote
Tell us the reference, dial colour, preferred year, condition and whether the warranty card is required, plus your budget and timing, through our sourcing enquiry form. We confirm the specific watch, photographs and final price before you commit.
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