Choose the Oris Divers Sixty-Five Calibre 400 38mm if a five-day power reserve and a 38mm case matter most; choose the TUDOR Black Bay 54 if you want a 200m water-resistance rating, a slimmer specified case, or a 20mm bracelet-and-strap width. The Oris is rated to 10 bar (100m) and has 120 hours of reserve. The TUDOR is rated to 200m and has approximately 70 hours of reserve. Neither is a universal winner: the better fit depends on your wearing habits, fit preferences, and how you value those differences.
At a glance: the key differences
| Specification | Oris Divers Sixty-Five Calibre 400 38mm | TUDOR Black Bay 54 |
|---|---|---|
| Reference | 01 400 7774 4057-07 8 19 18 | M79000B-0001 |
| Case diameter | 38mm | 37mm |
| Case thickness | Not stated on the Oris product page; Fratello reported 12.6mm in its July 21, 2024 comparison | 11.2mm |
| Water-resistance rating | 10 bar (100m) | 200m |
| Power reserve | 120 hours | Approximately 70 hours |
| Movement | Automatic Calibre 400, no date | MT5400 automatic, COSC-certified |
| Bracelet or strap fit | 19mm interhorn width; Oris lists a stainless-steel strap | 20mm lug width; three-link bracelet with T-fit clasp |
| Swiss-page price when accessed in 2026 | CHF 3,600; the page also showed the model as currently unavailable | CHF 3,850 suggested retail price |
Specifications and the dated Swiss-page prices are from the brands’ product pages: Oris Divers Sixty-Five Calibre 400 and TUDOR Black Bay 54. The Oris thickness figure is attributed to Fratello’s July 21, 2024 comparison; it is not a manufacturer figure in the surfaced product-page specifications.
Which watch fits your priorities?
Choose the Oris for its longer reserve
The Calibre 400’s stated 120-hour reserve is 50 hours longer than the TUDOR’s approximate 70 hours. In practical terms, the Oris can sit unworn for longer before it stops, assuming it was fully wound and the reserve is used under the conditions implied by the manufacturer’s specification. That can suit someone who rotates among watches during the week. The longer reserve is not evidence of better timekeeping accuracy; the comparison here is about stated running time.
Choose the TUDOR for its higher stated water resistance
The ratings are clearly different: Oris specifies 10 bar (100m), while TUDOR specifies 200m. That distinction may matter if your intended use makes the rating a deciding specification. The figures alone do not establish how either watch will perform in every real-world situation, so do not treat them as a substitute for the manufacturers’ guidance about use and maintenance.
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#1 Best Overall
- Model 01 733 7720 4051-07 5 21 02
Choose by fit and strap options, not diameter alone
The Oris is 1mm larger in diameter, while TUDOR specifies an 11.2mm thickness. The Oris product page does not state its thickness; Fratello reported 12.6mm and a 45.7mm length in its July 2024 comparison. Those are publication measurements, not official Oris specifications. Case diameter and thickness do not by themselves determine comfort, so try each watch on if fit is important.
The lug/strap widths also differ: 19mm on the Oris and 20mm on the TUDOR. That one-millimeter difference can narrow the strap options you shop for, and the widths are not interchangeable. TUDOR specifies a three-link bracelet with a T-fit clasp for this configuration; Oris lists a stainless-steel strap.
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- Brown Calf Leather Strap
Movement, certification, and daily wearing pattern
Both watches are automatic, but their stated reserves and movement credentials are not identical. Oris’s Calibre 400 is a no-date movement with 120 hours of reserve. The Black Bay 54’s MT5400 is COSC-certified and has approximately 70 hours of reserve. COSC certification is a specific credential stated for the TUDOR; it should not be confused with a head-to-head accuracy test of these two watches.
If you wear one watch continuously, the difference in reserve may be less important than fit, dial and case preference, or water-resistance rating. If you frequently rotate watches, the Oris’s five-day stated reserve is a concrete convenience. Neither figure says how accurately an individual watch will perform on your wrist.
Rank #3
- Oris Divers Sixty-Five Automatic Grey Dial Men's Watch 01 733 7707 4053-07 8 20 18
Warranty and servicing are structured differently
Oris says Calibre 400 models receive a 10-year warranty and recommends a 10-year service interval. Its product page also presents a two-year warranty that can be extended free to ten years through MyOris. The extension is tied to the program rather than automatic; check the applicable terms and complete the required registration steps.
TUDOR specifies a five-year transferable guarantee with no registration or periodic maintenance checks required. The two offers should not be treated as equivalent: one is an Oris program extension and recommended service interval, while the other is TUDOR’s stated guarantee and registration/maintenance-check policy.
Rank #4
- Warranty: This Oris comes with a 2-Year Factory Warranty. Box and papers are included.
- Bracelet: Black leather strap w/ stainless steel buckle. All watches are shipped to fit the average size wrist (7 1/4" - 7 1/2" for men and 6 1/4" - 6 1/2" for women).
- Dial: Grey w/ Superluminova C9 hands and hour markers
- Case: Stainless steel (40mm) w/ unidirectional rotatable bezel, minutes scale top ring and scratch resistant sapphire crystal
- Bobs Watches was founded in 1999 and is located in Newport Beach, CA. We believe in trust, honesty, and transparent pricing. With over 20 years of experience, and thousands of satisfied customers, we carry the world's largest selection of luxury watches
Price and availability depend on region and date
On the Swiss product pages accessed in 2026, Oris displayed CHF 3,600 and marked the model currently unavailable; TUDOR displayed a suggested retail price of CHF 3,850 for reference M79000B-0001. These are Swiss-page figures, not a like-for-like worldwide price guarantee, and Oris’s displayed price does not establish current stock.
For historical context only, Fratello’s July 21, 2024 comparison cited EUR 3,600 for the Oris and EUR 3,970 for the TUDOR on bracelet. Those dated euro amounts are not current quotes. Check the relevant brand page or an authorized seller in your market for current price, configuration, and availability.
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Best Value
- Featuring a Black Band, Silver-tone Case, Scratch Resistant Sapphire Crystal
- clasp type: Tang Buckle
- item shape: Round
Verdict: a conditional choice, not a single winner
- Pick the Oris if the five-day reserve, 38mm case, and Calibre 400 warranty program are the strongest draws for you—and a 10 bar rating meets your requirements.
- Pick the TUDOR if its 200m rating, 37mm case, specified 11.2mm thickness, COSC-certified movement, or 20mm bracelet configuration better matches your priorities.
- Try both on if the decision hinges on how a compact vintage-inspired diver wears. Their 1mm diameter difference is only one part of fit, and their strap widths lead to different accessory choices.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
