Tudor Caliber Mt5450 U

Tudor Caliber MT5450-U

Tudor Caliber Mt5450 U

Brand Tudor
Caliber Number MT5450-U
Base Caliber
Tudor MT5400
No (“Manufacture”)
Movement Type Automatic, self-winding mechanical
COSC Tested?
Master Chronometer?
Jewel Count
Beat Rate
28,800 vph, 4 Hz
Lift Angle
Power Reserve
65 hours
Rotor Style
Rotor Material
Tungsten monobloc
Rotor Winding Direction
Balance Wheel
Variable inertia style
Micro Regulator?
Anti-Shock Device
Hand Count 4
Functions Central hours; central minutes; central sweeping seconds; central GMT hand; date at 3:00
Hacking Seconds?
Up to 15,000 gauss
Sand-blasted with sun and radial laser grooving, chamfered/polished edges, laser engraved markings
Country of Manufacture Switzerland, Swiss made
Known Models
Tudor Black Bay 58 GMT (Ref: M7939G1A0NRU-0001, M7939G1A0NRU-0002) (Add your watch to the comments below…)

The Tudor caliber MT5450-U is a Swiss made automatic GMT watch movement based on the calibre 5400 framework. This “Manufacture Caliber” as Tudor calls it (MT in the caliber number stands for Manufacture Tudor), is found in the brand’s Black Bay 58 GMT models which was introduced during Watches and Wonders in April 2024.

Some of the topics covered in this caliber listing:

“True” GMT Function:

The GMT hand aka second time zone indicator of the MT5450-U, functions as what many watch publications like to call a true GMT. This means that the main hour hand (used to indicate the local time of the current time zone you are in) is set independently with the crown pulled out one click. The GMT hand is set with the overall time when the crown is pulled out 2 clicks. This doesn’t make it any more “true” of a GMT than other types of GMT movements (such as when the GMT hand is set independently on a so-called “caller” or office GMT), but since the original Rolex GMT-Master II had this functionality, it has been a desirable execution of this complication amongst the watch community.

MT5450-U VS MT5652:

In 2018, Tudor released the Black Bay GMT, powered by the cal. MT5652. You may be wondering what the differences are between these two movements and if the Black Bay 58 GMT is worth the upgrade. Here are some specs comparisons:

MT5450-U MT5652
Jewel Count 34 28
Power Reserve 65 hours 70 hours
6.14mm ~7.5mm

Thickness of the watches: Due to the difference in height of the movements, the original Black Bay GMT is 14.6mm thick, whereas the newer Black Bay 58 GMT is 12.8mm thick.

The same: The beat rate is the same 28,800vph (4Hz); the GMT functionality is the same; both have date calendar indicators at 3:00; both are made by Kenissi; both equipped with non-magnetic silicon balance springs.


The MT5450-U is a chronometer grade movement, testing and certified by COSC. Tudor states that the testing is done in six positions, at two temperatures, and with power reserve of 100% and again at 33%. This is excellent testing criteria because of the way watches can lose or gain time at different positions, temps and power reserve level throughout the day.

In Tudor’s own words:

“METAS Master Chronometer certification is comprehensive and covers the main functional characteristics of a watch including precision, resistance to magnetic fields, waterproofness and power reserve. Its standards are incredibly high, starting with precision. In order to qualify, a watch must be able to function within a 5-second range of variation each day (0/+5), that is to say 5 seconds less than the Official Swiss Chronometer Testing Institute (COSC) (-4/+6) carried out on uncased movements and a second less than TUDOR’s internal standard (-2/+4), which is applied to the brand’s models with a Manufacture Calibre. The certification also guarantees the timekeeping accuracy of a watch subjected to magnetic fields of 15,000 gauss. Finally, it also guarantees the waterproofness claimed by the manufacturer as well as the power reserve. It should also be noted that two prerequisites are necessary before the certification can be obtained: Swiss manufacturing must conform with the criteria of Swiss Made, and the movement must be certified by the Official Swiss Chronometer Testing Institute (COSC).” -Tudor Black Bay 58 GMT Official Press-Release, 2024, page 4 (link below)

More on accuracy:

“It is certified as a chronometer by the Official Swiss Chronometer Testing Institute (COSC), with its performance going beyond the standards set by this independent institute. In fact, where COSC allows an average variation in the daily rate of an uncased movement of between -4 and +6 seconds and TUDOR applies a 6-second (-2/+4) variation standard on its fully assembled watches, METAS requires a Master Chronometer certified watch to run within a tolerance range of 5 seconds (0/+5). Not only is the Manufacture Calibre MT5450-U certified to be more accurate, it is also rated as anti-magnetic, making it impervious to magnetic fields below 15,000 gauss.” -Tudor Black Bay 58 GMT Official Press-Release, 2024, page 5

Power Reserve:

The MT5450-U has a runtime of up to 65 hours when fully wound. This is what Tudor likes to refer to as “weekend-proof”, since it allows the wearer to take off their watch on Friday night and it will still be running when they put it on for work Monday morning.

“Another notable feature is that the power reserve of the Manufacture Calibre MT5450-U is “weekend-proof”, about 65 hours. This enables the wearer to take the watch off on a Friday evening and put it back on again on Monday morning without having to reset.” -Tudor Black Bay 58 GMT Official Press-Release, 2024, page 5 (bottom paragraph)

Editor’s Commentary: This idea of a watch being marketed as “weekend-proof” always baffles me. Your $4,600 USD watch is not meant to be worn on the two days that you waited all week for. Why would a luxury watch brand put the idea in their customers’ minds that they should take off and not enjoy their watches during the weekend? Especially a tool watch which many might not feel comfortable wearing under a dress shirt. In other words, the weekend seems like the perfect time to put on the Black Bay GMT sport watch. Not only that, but how about encouraging wearing the watch all week long? A better way to work in the benefits of an extended power reserve, would be to put it in terms of freedom to wear other Tudor watches without worrying about setting the watch again in a few days – this would also plant the idea of acquiring more Tudors.

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