Patek Philippe

Nautilus Annual Calendar 5726A

Name: Patek Philippe Nautilus Annual Calendar 5726A 5726A-001
Brand: Patek Philippe
SKU: 5726A-001

Ref. 5726A-001

2011–present · 40.4mm · caliber Patek Philippe Cal. 324 S QA LU 24H: in-house automatic, 28,800bph, 45h PR; annual calendar (requires single correction per year, at March 1) + moonphase + 24h indicator; integrated in Nautilus sports case

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Movement tier: unclassified · caliber Patek Philippe Cal. 324 S QA LU 24H: in-house automatic, 28,800bph, 45h PR; annual calendar (requires single correction per year, at March 1) + moonphase + 24h indicator; integrated in Nautilus sports case · 45h power reserve · see-through caseback · family design Gérald Genta

Medium-large: suits wrists 6.5 in+ (16.5 cm+)

40.4 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

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Authentication

The 5726A shares all Nautilus case and bracelet authentication tells with the 5711/1A, plus complication-specific checks for the annual calendar and moonphase that separate genuine from fake.

Known issues in the market

All 5711/1A forgery methods apply to the 5726A; the additional complication modules are rarely replicated to correct standard.
Annual calendar disc alignment in fakes is often imprecise; date, day, and month discs frequently show slight misregistration.
The moonphase disc is a common quality shortcut; genuine Patek discs have realistic three-dimensional stars and a correctly shaped moon silhouette.

Area	What to check	What is correct	Red flag
dial	Annual calendar disc printing and alignment	Date, day, and month discs all perfectly centered through their apertures; fine-print text on discs is crisp and correctly weighted; discs transition cleanly at midnight	Any misalignment of disc text through apertures; blurred or heavy-weight disc printing; discs that jump erratically
dial	Moonphase disc quality	Deep blue disc with realistic painted star field; moon shape is correctly rounded and three-dimensional; disc transitions smoothly over 29.5-day cycle	Flat printed disc with two-dimensional stars; incorrect moon shape; disc that advances in uneven jumps
case	Correction pushers at 8 and 10 o'clock	Two pushers present and functional; each corrects a specific calendar function; pusher profiles match case finishing (brushed sides, polished faces)	Missing pushers; non-functional pushers; pusher finishing inconsistent with case
case	Alternating brushed and polished case finishing	Identical finishing standard to 5711/1A; razor-sharp transitions between brushed and polished surfaces	Soft or blended transitions; uniformly polished or brushed case sections
bracelet	Integrated bracelet and clasp	Seamless case-bracelet junction; alternating link finishing; Patek double-fold clasp with Calatrava cross	Gap at case-bracelet junction; soft link finishing transitions; missing Calatrava cross on clasp
caseback	Exhibition caseback and Cal. 324 S QA LU movement	Exhibition caseback shows Cal. 324 S QA LU 24H; significantly more complex module architecture than base 5711 movement; blued screws, perlage on plates, beveled bridges	Solid caseback; movement complexity does not match annual calendar specification; un-blued screws

Common legitimate replacements

Bracelet clasp spring replacement is common; confirm correct Patek double-fold with Calatrava cross.
Crystal replacement after impact; confirm correct Patek sapphire.

Expert resources: Patek Philippe boutiques offer authentication. Phillips Geneva Watches online archives have 5726A auction records useful for reference comparison. For purchases above $60,000, major auction house specialists are advisable.

Authentication guide

Last reviewed June 2026

The 5726A combines the Nautilus case with an annual calendar and moonphase. The complication complexity makes high-quality reproductions rare. Functional testing of the annual calendar and moonphase mechanisms is the most reliable authentication path.

Known reproduction risks

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MEDIUM

The 5726A is less replicated than the 5711 due to the complication complexity. A convincing functional fake requires an annual calendar mechanism that actually works, which dramatically increases production cost. The moonphase and multiple apertures are the natural inspection focus.

Moonphase disc color: faded or flat vs. deep saturated blue with gilded moon
Dial texture: same embossed horizontal grooves as the 5711; flat printed lines indicate a non-original dial
The aperture windows should be cleanly cut with no rough edges; the disc surfaces seen through the apertures should be matte and richly colored
Annual calendar function: test by advancing the date corrector through a complete month cycle. Any mis-advance exposes a non-functional calendar module.

Functional testing of the annual calendar across multiple months is the most reliable authentication path for the 5726A. A watch that cannot demonstrate correct calendar advancement is not suitable for purchase regardless of visual appearance.

Dial variants by era

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Era	Description	Identifiers
2012 to present	Blue-grey sunburst dial with the same horizontal embossed grooves as the 5711, plus additional subdial apertures for day, date, month, 24-hour display, and moonphase.	Three aperture windows across the dial: day at 12 o'clock, date at 3 o'clock, month at 6 o'clock Moonphase display at 6 o'clock beneath the month aperture 24-hour subdial at 9 o'clock The same directional blue-grey sunburst texture and embossed horizontal grooves as the 5711 Applied baton hour markers in white gold; no numerals "ANNUAL CALENDAR" and "MOON PHASES" text arced across the lower dial

Service part flags

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Moonphase disc

Original: Deep blue disc with gilded moon and star decorations. The Patek moonphase is accurate to 122 years before a one-day correction is needed. The disc surface should be rich, saturated blue with bright gilded elements.

Replacement tells

Disc color is flat or faded rather than deep saturated blue
Gilded moon and stars appear dull, printed, or incorrectly colored (silver rather than gold)
Moonphase display advances in a stutter or jumps more than one increment per press of the corrector

Annual calendar mechanism

Original: The annual calendar correctly advances through months with 30 and 31 days without manual correction, requiring only one adjustment per year: advancing the date manually on March 1st (since February has 28 or 29 days).

Replacement tells

The date requires manual correction on months other than the February-to-March transition
The day aperture does not advance at midnight (indicating a date-only mechanism rather than a full annual calendar)
Month aperture does not advance automatically at the end of each month

Integrated bracelet

Original: Same Nautilus bracelet as the 5711: H-shaped links tapering from case to clasp, polished center links, brushed outer links, fold-over deployant with Patek crown logo.

Replacement tells

Bracelet taper absent; links maintain uniform width from case to clasp
Link finishing quality inconsistent between adjacent links
Clasp deployant does not lock positively in the closed position

Case back markings

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2012 to present

Sapphire exhibition caseback showing Cal. 324 S QA LU 24H
Annual calendar module visible above the base movement
Côtes de Genève finishing on bridges; blued screws
Signed rotor with "PATEK PHILIPPE GENEVE" and Calatrava cross
Reference and serial number engraved on the inner case ring

Movement tells

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Cal. 324 S QA LU 24H runs at 28,800 bph. A timegrapher reading significantly outside +/- 3 s/day indicates the movement needs service or regulation.
The annual calendar mechanism is driven by a cam system that reads month length. If the calendar advances incorrectly on any month other than February-to-March, the cam system has failed or been incorrectly serviced.
The moonphase disc should advance once per lunar day. After a new moon, the disc should show the moon at the 6 o'clock position of the aperture. Incorrect phasing indicates either an incorrectly set moonphase or a non-original disc.
The 24-hour hand at 9 o'clock should complete one full rotation every 24 hours. If it completes a rotation in 12 hours, the hand has been replaced with an incorrect component.
Finishing quality under the caseback: the annual calendar module should show even, parallel Côtes de Genève stripes on all visible bridges. Any bridge with inconsistent stripes or no finishing indicates a replacement or non-Patek service part.

Sources: Patek Philippe Nautilus Annual Calendar reference page; Patek Philippe Cal. 324 S QA LU 24H technical documentation; Hodinkee -- Patek Annual Calendar complication guide.