Rolex · Datejust

Strap for Rolex Datejust 1603

Takes 20 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width20 mm
Case diameter36 mm
Reference1603
FamilyDatejust
MovementRolex Caliber 1570
CaseStainless Steel
CrystalAcrylic
BezelEngine-turned bezel
Water resistance100m

Recommended spring bar

Spring bars Datejust 36 steel — 20mm drilled lugs

Verified compatibility for this reference · lug 20 mm · Ø 1.8 mm · drilled lugs

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Straps for the Datejust 1603

Selected for the 20 mm lug width · workshop selection

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The Datejust 1603, seen from the bench

The Rolex Datejust 1603, produced from 1960 to 1977, is a stainless steel sports watch with a 36 mm case and Engine-Turned bezel. Powered by the Caliber 1570 automatic movement with bidirectional winding, it features a mineral crystal and offers reliable daily accuracy. The 20 mm lug width ensures broad compatibility with aftermarket straps, making it highly versatile for different occasions and styles.

Frequently asked questions

What is the lug width of the Rolex Datejust 1603?

The Rolex Datejust 1603 has a lug width of 20 mm, measured between the inner walls of the case lugs. This measurement has remained consistent across the entire Datejust 36 family produced by Rolex for decades, ensuring broad compatibility with quality aftermarket straps.

What is the best strap for the Rolex Datejust 1603?

The ideal choice depends on intended use and aesthetic preference. For formal occasions, an alligator strap in Mississippiensis grain with a steel deployant clasp complements the Oyster case elegantly. For everyday wear, a vegetable-tanned calf leather strap develops a distinctive patina that ages well alongside the classic dials of the 1603. A NATO strap remains the most practical option for sporting or summer use.

How do you change the strap on a Rolex Datejust 1603?

To replace the strap on a Datejust 1603, you will need a spring bar tool to remove the spring bars connecting the strap to the lugs. This is a straightforward procedure, though care must be taken to avoid scratching the case: protect the lugs with adhesive tape and work on a soft surface. Alternatively, any watchmaker or authorised dealer can perform the swap in a matter of minutes.

Are there aftermarket straps compatible with the Rolex Datejust 1603?

Yes. The standard 20 mm lug width and lug geometry of the Datejust 1603 are widely supported by quality strap manufacturers. Milanostraps.it offers a curated selection of handcrafted 20 mm compatible straps in alligator, vegetable-tanned calf leather, shell cordovan, NATO nylon and vulcanised rubber, all supplied with spring bars included.

How long does a leather strap last on a Rolex Datejust 1603?

Longevity depends on the type of leather and conditions of use. A quality vegetable-tanned calf leather strap, worn daily on a rotating basis and properly stored, typically lasts between two and four years before showing significant wear at the stitching or keeper. Alligator and shell cordovan straps, owing to the density of the material, tend to last considerably longer. Avoiding prolonged exposure to water and perspiration will significantly extend the lifespan of any leather strap.

The next step

The right strap isn't chosen. It is built, together.

From the atelier appointment to delivery, every step is made for those who know that things done well take time. Rare leathers, one piece at a time, eighteen months of warranty.

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Casati Milano · Via XX Settembre 15, Milan · by appointment only