Tudor T603 Sellita Sw240 1

Tudor Caliber T603

Tudor T603 Sellita Sw240 1

Manufacturer Tudor
Caliber Number T603
Base Caliber
Movement Type
Automatic, self-winding mechanical
In-House? No
Not enough info
Diameter 33.3mm
Thickness 5.5mm
Vibrations Per Hour 28,800 bph (4 Hz)
Lift Angle
50 degrees (as per Sellita)
Power Reserve 38 hours
Rotor Ball bearing
Barrel Spring
Hacking? Yes
Functions Hours, minutes, central sweeping seconds, day of the week at 12:00, date at 3:00
Country of Manufacture Switzerland
Known Models
Tudor Royal (Model reference numbers and configuration options are below…)

The Tudor caliber T603 is a Swiss made automatic movement found in Tudor Royal watches. This caliber is powers the larger 41mm Day/Date Royal models. Watches with this movement were announced in 2020.

Tudor made by Sellita:

Sellita Sw240 1 Drawings

The Tudor T603 is based on a Sellita caliber. You may see other sites incorrectly list the T603 as being based on a Sellita 2834. There is no such thing as a Sellita 2834. There is an ETA 2834-2 which the Sellita SW240-1 is a clone of. Therefore, it is safe to assume that the T603 is based on the Sellita caliber SW240-1, making it a clone of a clone.

Interestingly, the Tudor documentation lists the T603 as having 25 jewels, however, the Sellita caliber SW240-1 actually contains 26 jewels (one extra jewels when compared to the ETA 2834-2, much like the difference between an SW200-1 and ETA 2824-2).

Other discrepancies between Tudor and Sellita info include the diameter. Tudor lists a diameter of 33.3mm, whereas Sellita lists 29.4mm diameter (with a 29mm case fitting diameter). Also, thickness: Tudor says 5.5mm, Sellita says 5.05mm.

If you want to dig deeper into the background of the T603, the SW240-1 is based on the SW200-1 with an additional outer day of the week complication. Learn more about the SW200-1 here.

Is it an officially certified chronometer?

Although Tudor does not write “Chronometer” across the dial of the Royal, their official marketing says this about the movement inside:

“Swiss self-winding mechanical calibre T603 with chronometer performance”

So does “chronometer performance” means is it an officially certified chronometer or not? This sounds like they are claiming a chronometer-like timekeeping experience, without an actual chronometer certification to go along with it. If this is the case, it could be that they are using a Premium (Top) grade Sellita which runs close to COSC spec but without the official certification.

Sellita’s Premium grade is tested in 5 positions and tests out at an average of +/- 4 seconds per day with a maximum divergence of 15 seconds/day. For COSC, the movement must keep time within an average rate of -4/+6 seconds per day over the span of testing (at least 15 days).

When should the Day/Date change?

Tudor officially states that the day of the week at 12:00 and date at 3:00 are “semi-instantaneous”. You will likely not notice any delay of the day/date changing over at midnight, but don’t be surprised if the advancing changeover occurs slightly before or after the hands strike 12:00 AM.

Recommended Service Intervals:

Tudor recommends that its watches be serviced approximately every 10 years depending on the model and real-life usage.

Caliber T603 Warranty:

Watches powered by the Tudor caliber T603 movement are covered by a 5 year manufacturer’s warranty. Actually, Tudor calls it a “guarantee” rather than a warranty. Tudor clearly states that this guarantee is transferable, so when you purchase a pre-owned watch or sell your watch, it will still be covered within five years from the original date of purchase. Tudor also states that no registration is necessary for coverage, nor are periodic maintenance checks.

List of Tudor watches with caliber T603:

As of this post, the T603 movement is found in the following 12 Tudor Royal watch configurations…

Reference Dial Case/Bracelet
M28600-0001 Silver All steel
M28600-0002 Silver with diamonds All steel
M28600-0003 Black All steel
M28600-0004 Black with diamonds All steel
M28600-0005 Blue All steel
M28600-0006 Blue with diamonds All steel
m28603-0001 Silver Steel, yellow gold TT
m28603-0002 Silver with diamonds Steel, yellow gold TT
m28603-0003 Black Steel, yellow gold TT
m28603-0004 Champagne Steel, yellow gold TT
m28603-0005 Black with diamonds Steel, yellow gold TT
m28603-0006 Champagne with diamonds Steel, yellow gold TT

All watches with the caliber T603 are 41mm diameter.

Retail prices range from $2,325 to $3,975 USD depending on configuration.

Editor comment: It looks like someone at Tudor messed up the flow of reference numbers. The watches were in order of dial color and dial color with diamonds, but when it gets to the two-tone models with black or champagne dials, the sequence is out of order.

Examples of watches with this movement:

Additional Resources:

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Matt Briggs
Matt Briggs
3 years ago

This one is definitely NOT a Rolex lol

3 years ago
Reply to  Matt Briggs

Rolex makes TUDOR, is like Toyota and Lexus, Or Ford and Lincoln. so nothing wrong with Tudor looking like Roles, they are the same company, and it has been like this for more than 80 years. same founder.

2 years ago
Reply to  nik

Same founder. Not the same company. Both are owned by the Hans Wilsdorf Foundation, but they shared eno production facilities or management.

1 year ago
Reply to  nik

Tudor is not made by Rolex. They are owned by the same foundation (Hans Wilsdorf Foundation). Would you say Dior is made by LV? Because they are both under LVMH.

2 years ago

Tudor state that the T603 is also used in the Tudor Glamour Day Date range, which have a 39mm diameter. Perfect for me!

Martti O. Suomivuori
Martti O. Suomivuori
2 years ago

It is amazing how much digging in the dirt you must do to finally find out that all the Swiss high-end wannabees actually hide a Sellita clone behind their fancy façades. If only they’d indicate which grade of Sellita they have adopted! It seems that brand is all that matters. I’d like to hear less marketers and more watchmakers.

2 years ago

The idea of a daily driver watch without the long term higher dollar service costs is a bad thing?
You can get a very nice Tudor Glamour Day Date for under 2 grand. You don’t have to dig in any dirt and the movements are modified by Tudor. Silly comment.

Martti O. Suomivuori
Martti O. Suomivuori
2 years ago
Reply to  Robert

What? Can you even read?

2 years ago

Tudors history is non in-house watches. Since when do I need to do tons of digging to find that out? I agree it would be ideal to know more of caliber grade. I also assume by fancy facade, you mean dial. Your post still makes zero sense. This is Tudors history. I’m regards to Tudor, I do think it sucks a black bay 36 is not in-house. However sub 2k, who cares. I could never buy a BB36 when I know the 58 does bring so much more. I would save the extra 1750. That is a example I guess… Read more »

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