Watch assembly stages explained: T0, T1, T2 and T3

Why assembly is split into stages

A watch is assembled in several steps, often by different people and sometimes by different companies. For efficiency and logistics, the industry groups these steps into four stages, labelled T0 to T3. Suppliers use these labels in quotes and conversations, so knowing them helps you ask for the right service.

The exact boundaries vary slightly from one company to another, especially for T3. Always confirm what a supplier includes in each stage.

T0: pre-assembly of components

T0 covers the preparation of movement parts before the movement itself is assembled: for example, setting the jewels and pins in the main plate and bridges. It is usually done by the movement manufacturer or its suppliers.

As a brand buying a finished movement, you rarely deal with T0 directly. It matters if you commission a modified or exclusive movement. See the movement component suppliers in our index.

T1: movement assembly

T1 is the assembly of the movement: the gear train, the escapement, the balance and any complications are fitted, lubricated and adjusted. The movement is then regulated and its timekeeping checked.

Most micro-brands buy movements already assembled and regulated from a movement supplier. Some workshops also offer movement assembly or customisation, such as decoration or a custom rotor.

T2: dial, hands and casing

T2 turns a movement into a watch head. It typically includes:

• fitting the dial onto the movement;
• setting the hands, aligned and with correct clearance;
• casing: placing the movement, dial and hands into the case, fitting the stem and crown, and closing the case.

This is the stage most micro-brands outsource, because it requires a clean workshop, specific tooling and experienced watchmakers. Browse the assembly and casing workshops in our index.

T3: water resistance, strap and finishing

T3 completes the watch. It usually includes water resistance testing of the cased watch and fitting the strap or bracelet. Depending on the workshop, it can also cover final checks, the presentation box, documentation and packing.

If you plan a water-resistance rating on the dial or case back, agree with the workshop how each watch will be tested, and keep the results.

Quality control along the way

Checks happen throughout assembly: timekeeping after T1, the alignment of dial and hands and the absence of dust during T2, water resistance and appearance at T3. The number and type of checks depend on the workshop and on what you agree with it.

Ask each workshop which checks it performs, whether it measures timekeeping after casing, and how it reports defects. Agree on acceptance criteria before production, not after delivery.

Assembly and Swiss Made

Assembly stages are directly linked to the Swiss Made rules. For a watch to be Swiss, its movement must be Swiss, which means among other things that it is assembled in Switzerland; the movement must also be cased up in Switzerland, and the final inspection by the manufacturer must take place in Switzerland.

In practice, if you aim for Swiss Made, T1 and T2 cannot be moved abroad, and your final inspection must happen in Switzerland. Read Swiss Made rules explained for the full conditions.

What a micro-brand usually outsources

• Buy: an assembled, regulated movement (T0 and T1 done by the movement supplier).
• Outsource: dial and hand fitting, casing, water resistance testing and strap fitting (T2 and T3) to an assembly workshop.
• Or delegate everything: a private label manufacturer coordinates all stages and delivers finished watches. Compare the routes in private label or your own supply chain.

When you contact a workshop, say which stages you need (for example, T2 and T3 with your own movements, dials and cases), how many pieces, and whether you aim for Swiss Made. Our guide How to write a sourcing request includes a template.