When Tudor unveiled its first manufacture movement in 2015, the watch world took notice. For decades, Tudor had relied on supplied calibres — respected workhorses from ETA and Sellita — while the sibling brand upstairs at Rolex polished its own movements. The in-house push changed the conversation: Tudor was no longer just the value play on the same wrist size; it was a manufacture in its own right. A decade on, the MT5xxx calibre family powers every important Tudor reference, and the 2025 introduction of METAS Master Chronometer certification has raised the bar further still.
If you own a Tudor or you’re shopping for one, understanding the calibres matters. The difference between an MT5601 and an MT5601-U is not cosmetic — it’s the difference between COSC chronometer performance and Master Chronometer certification with 15,000-gauss magnetic resistance. This guide covers each calibre in the family: its specifications, where it appears, and what it means for daily ownership.
The Kenissi Connection: Where Tudor Movements Come From
To understand what “manufacture” means for Tudor, you need to know Kenissi SA. Kenissi is a movement manufacturer based in Le Locle, Switzerland — the watchmaking heartland of the Vallée de Joux region. The company was established in 2017 as a joint venture to give Tudor access to movements it could genuinely call its own, without requiring Rolex to open its manufacturing floors to a separate brand. Rolex holds a 20% stake in Kenissi; Chanel is also a stakeholder and customer.
The corporate structure occasionally prompts debate — some purists prefer movements developed entirely within a single building under a single brand. What matters for practical assessment is this: COSC chronometer and METAS Master Chronometer certifications are awarded to the movement itself, tested on its own merits, regardless of who owns the factory. Tudor’s MT5xxx calibres earn those certifications through measurable performance, and Kenissi produces them specifically to Tudor’s specification. That is what the watchmaking industry means by manufacture.
The MT5601: Tudor’s Foundation Stone
The MT5601 made its debut in the Tudor Pelagos in 2015. Its headline specification at launch was a 70-hour power reserve — at a time when most Swiss movements in this price category offered 42 to 48 hours, the MT5601’s extended reserve was a meaningful differentiator. Missed the charger over the weekend? Your Tudor kept running.
The full specification of the MT5601:
- Frequency: 28,800 vph (4 Hz) — the industry standard for dive-watch calibres, giving good positional accuracy
- Power reserve: 70 hours (approximately three days)
- Balance spring: Silicon — anti-magnetic, requires no lubrication, and maintains elasticity more consistently than traditional hairsprings over time
- Self-winding: Bidirectional variable-geometry rotor, which adjusts its weighting to wind efficiently across different activity levels
- Certification: COSC chronometer (±4 seconds per day across five positions)
- Complication: Hours, minutes, seconds — no date display
The silicon balance spring deserves a note. Silicon components became practical in watchmaking in the 2000s, with Patek Philippe and Rolex leading early adoption. Silicon is naturally anti-magnetic — it doesn’t respond to magnetic fields the way a steel hairspring does — and it needs no oil to function properly. Both properties mean the calibre maintains accuracy more consistently over years of use, without the degradation that occurs as lubricants break down.
The MT5601 powers a wide range of references: the original Black Bay (reference M79220), the Black Bay Dark, the Black Bay Bronze, the Black Bay 32 (ladies), and earlier Pelagos variants. Its longevity in the lineup is a testament to how well the fundamental architecture was conceived.
The MT5602 and MT5652: The Family Grows
The MT5602 shares the MT5601’s core architecture — same frequency, same power reserve, same silicon spring, same COSC certification. Tudor introduced it as the movement for the Black Bay 41 (reference M79230), and it has appeared in subsequent Black Bay references. From a performance standpoint, the MT5602 and MT5601 are functionally identical; the separate designation tracks engineering revisions and simplifies service records for different references.
The MT5652 adds a date complication to the platform. It appears in the Black Bay Date and date-equipped variants across the range. The power reserve, frequency, and silicon balance spring carry across unchanged. The date module adds a modest amount to the movement’s depth, but Tudor has engineered the package to fit the existing case families without compromising water resistance or crown placement.
The MT5400 Family: Powering the Black Bay 58
While the MT56xx calibres handle the larger Black Bay references, the MT5400 family was developed for the Black Bay 58 — the 39mm watch named for the 1958 Big Crown reference that is one of Tudor’s most celebrated vintage designs. The smaller case required a calibre sized appropriately for the diameter, and the MT5400 fills that role.
The MT5400 maintains the same headline specifications as its siblings: 70-hour power reserve, 28,800 vph, silicon balance spring, COSC certification, bidirectional rotor. The physical dimensions of the calibre are suited to the 39mm case, but the movement’s performance ambitions are identical to the larger-case versions. Tudor did not compromise the specification to fit a smaller watch.
The MT5400-U is the METAS Master Chronometer variant of the MT5400, used in the Black Bay 58 Burgundy and other select METAS-certified BB58 editions. Like all “-U” suffix Tudor calibres, it meets the 15,000-gauss anti-magnetic requirement and the tightened accuracy standard.
COSC vs METAS: What the Certifications Actually Mean
Tudor’s calibre lineup spans two certification tiers, and the difference between them is worth understanding clearly before choosing which reference to buy.
COSC (Contrôle Officiel Suisse des Chronomètres) is the long-established Swiss chronometer standard. A movement earns COSC certification by running within ±4 seconds per day across five positions and three temperatures, tested as a bare movement (not yet installed in a case). COSC is a rigorous standard — only a fraction of movements produced earn the chronometer designation — and an MT5601 running at COSC specification is an accurate, reliable calibre by any practical measure.
METAS (Master Chronometer) is a newer, more demanding standard developed by Switzerland’s Federal Institute of Metrology. The key differences from COSC:
- The cased watch is tested, not the bare movement. METAS certification applies to the complete watch as it will be worn — seals, crown, crystal and all.
- Accuracy standard: -0 to +5 seconds per day (tighter than COSC, and asymmetric — running slow is not permitted)
- Magnetic resistance: The watch must function accurately inside a 15,000-gauss field. Most environments produce fields under 1,000 gauss; an MRI machine operates at roughly 15,000 to 30,000 gauss. A METAS Tudor can withstand the magnetic environment of most hospital equipment.
- Power reserve verification: The stated power reserve must be accurate to the tested watch, not just the spec sheet.
For most buyers, the practical gap between COSC and METAS is narrow in daily life — COSC accuracy is well within what human perception can detect on a daily schedule. The meaningful real-world advantage of METAS is the magnetic resistance, which protects against accuracy loss near strong electronics, medical equipment, or certain industrial settings.
The MT5601-U: Master Chronometer Arrives in the Black Bay 68
Watches & Wonders 2025 brought one of Tudor’s most significant movement announcements in a decade: the Black Bay 68 with the MT5601-U, the first MT56xx calibre to carry METAS Master Chronometer certification.
The watch itself is named for Tudor’s 1968 Oyster Prince Submariner reference, and the 38mm case size splits the difference between the Black Bay 36 and Black Bay 41. Both launch variants — blue sunburst and silver sunburst dials — feature an integrated steel bracelet with micro-adjustment on the clasp and a screwdown crown rated to 200 metres. “MASTER CHRONOMETER” appears below 6 o’clock on the dial, a text string that indicates the upgraded certification to any observer.
The MT5601-U retains all the strengths of the MT5601: 70-hour power reserve, silicon balance spring, 28,800 vph, bidirectional variable-geometry rotor. The upgrade is in the certification tier — 15,000-gauss magnetic resistance and the METAS accuracy standard — and in the anti-magnetic construction required to achieve it. Tudor has not disclosed the specific internal changes beyond what METAS certification requires, but the escapement components are necessarily engineered to resist magnetic interference at the specified threshold.
The Complete Calibre Comparison
Here is the full Tudor manufacture calibre family at a glance:
| Calibre | Power Reserve | Frequency | Certification | Date | Key References |
|---|---|---|---|---|---|
| MT5601 | 70 hours | 28,800 vph | COSC | No | Black Bay (M79220), BB Dark, BB Bronze, Pelagos |
| MT5602 | 70 hours | 28,800 vph | COSC | No | Black Bay 41 (M79230) |
| MT5652 | 70 hours | 28,800 vph | COSC | Yes | Black Bay Date |
| MT5400 | 70 hours | 28,800 vph | COSC | No | Black Bay 58 (standard) |
| MT5400-U | 70 hours | 28,800 vph | METAS ✓ | No | Black Bay 58 Burgundy |
| MT5601-U | 70 hours | 28,800 vph | METAS ✓ | No | Black Bay 68 (2025) |
Ownership, Service, and Resale
Tudor recommends servicing its manufacture movements at approximately 10-year intervals. The recommendation is consistent with modern watchmaking norms — silicon balance springs require no lubrication, which was one of the main drivers of shorter service intervals in earlier movements. At an authorised Tudor service centre, the MT5xxx calibres are fully supported with Kenissi-sourced parts. Unlike watches running on Sellita or ETA movements, there is no dependence on a third-party supply chain for major components.
The silicon balance spring also affects long-term accuracy retention. Traditional steel hairsprings can be affected by lubricant degradation, magnetic exposure, and physical stress over years of wear. Silicon avoids all three. A well-kept MT5601 or MT5602 should hold its accuracy closer to factory specification at the 7- or 8-year mark than an equivalent steel-spring movement.
On the resale market, Tudor manufacture references have held value well. The shift away from outsourced calibres is broadly understood by buyers, and the COSC certification commands a consistent premium over equivalent non-certified watches. METAS-certified references — the BB58 Burgundy, the Black Bay 68 — are newer and their resale trajectory is still developing, but the positioning above standard COSC models appears stable in early secondary market data.
One practical note for buyers considering pre-owned: verify the reference number. A Black Bay 58 running an MT5400 (COSC) and a Black Bay 58 running an MT5400-U (METAS) look nearly identical on the dial — the difference is the word “MASTER CHRONOMETER” below 6 o’clock. The reference number confirms the specification unambiguously.
Frequently Asked Questions
Tudor’s movements are produced by Kenissi SA, a company based in Le Locle, Switzerland, in which Tudor’s parent group and Rolex hold stakes. The movements are designed and manufactured to Tudor’s specification and earn COSC and METAS certifications independently. The watchmaking industry considers movements produced at Kenissi to be genuine manufacture calibres.
Both the MT5601 and MT5602 share the same core architecture: 70-hour power reserve, 28,800 vph frequency, silicon balance spring, bidirectional rotor, and COSC chronometer certification. They are non-date calibres. The MT5602 was developed for the Black Bay 41 and carries the engineering revision suited to that reference. Daily performance is functionally identical between the two.
The “-U” suffix — as in MT5601-U or MT5400-U — indicates a METAS Master Chronometer-certified variant of the base calibre. These movements meet the -0/+5 seconds per day accuracy standard tested in the cased watch, and resist magnetic fields up to 15,000 gauss. They carry the METAS certification plaque and the text “MASTER CHRONOMETER” on the dial.
As of 2025, METAS-certified Tudor references include the Black Bay 68 (MT5601-U, launched at Watches & Wonders 2025) and the Black Bay 58 Burgundy and select other Black Bay 58 editions (MT5400-U). Tudor has indicated that METAS certification will be extended progressively across the manufacture range.
Tudor recommends servicing its manufacture calibres at approximately 10-year intervals, consistent with modern industry standards. The silicon balance spring requires no lubrication, which contributes to the extended service interval. Authorised service centres use Kenissi-sourced parts, and all MT5xxx calibres are fully supported.
METAS (Master Chronometer) is a more demanding standard than COSC in two key ways: it tests the cased watch rather than the bare movement, and it requires the watch to function accurately inside a 15,000-gauss magnetic field. The accuracy tolerance is also tighter (-0/+5 sec/day vs COSC’s ±4 sec/day). For practical daily use, both standards deliver more than adequate accuracy. METAS offers a meaningful advantage if you’re regularly near strong magnetic sources.
The Verdict
Tudor’s MT5xxx family is one of the more coherent movement stories in Swiss watchmaking. The platform that began with the MT5601 in 2015 has been refined consistently without being reinvented unnecessarily — the same silicon spring, the same 70-hour reserve, the same COSC-certification discipline — and the 2025 introduction of METAS variants marks the most significant upgrade yet. The MT5601-U in the Black Bay 68 and the MT5400-U in the Black Bay 58 represent Tudor’s direct engagement with Omega’s Master Chronometer benchmark: the same testing institute, the same standard, the same 15,000-gauss threshold.
For buyers, the practical takeaway is straightforward. Any MT56xx or MT54xx calibre — COSC or METAS — is an excellent movement with excellent long-term support. The choice between COSC and METAS comes down to whether the magnetic resistance and tighter accuracy tolerance are worth paying for in the specific reference you’re considering. If they are, the Black Bay 68 and Black Bay 58 METAS editions are the references to look at. If COSC accuracy is more than sufficient for your use, the core MT5601 and MT5602 models represent outstanding value at their respective price points.
