Black Bay 58

Ref. M7939A1A0NU

Case diameter: 39 mm; Manufacturer spec
Lug-to-lug: 47.8 mm; Measured in a published review
Thickness: 11.7 mm; Measured in a published review
Lug width: 20 mm; Measured in a published review

Retail price $5,350 (US, Oct 2026)

Your wristIdeal fit

Wrist flat: 55.1 mmLug-to-lug: 47.8 mm

How the Black Bay 58 wears

Its lugs reach 8.8 mm past the 39 mm case, more than the 7.1 mm typical across the almanac, so it wears larger than its diameter suggests.

On our fit model it sits best on wrists from 6.75" to 8" (17.1–20.3 cm); below 6.75" the lugs start to reach the edge of the wrist.

At 11.7 mm thick it is slimmer than 90% of the 79 other dive watches we've measured, so it slides under a cuff more easily than most.

Its 20 mm lug width is one of the most common strap sizes; 104 other watches here share it, so aftermarket straps are easy to find.

Will the Black Bay 58 fit your wrist?

With a 47.8 mm lug-to-lug, here is how it wears across common wrist sizes. We estimate the flat top of each wrist from its circumference; measure yours for a closer answer in the fit finder.

Wrist	Flat width (est.)	Fit
6"	47.2 mm	Lugs overhang
6.5"	51.2 mm	Snug, lugs near the edge
7"	55.1 mm	Ideal fit
7.5"	59.1 mm	Ideal fit
8"	63 mm	Ideal fit

Specifications

Reference: M7939A1A0NU
Collection: Black Bay 58
Status: In production
Introduced: 2026
Case material: stainless steel
Crystal: sapphire
Water resistance: 200 m
Bezel: unidirectional rotatable, steel with anodised aluminium insert
Dial: matte black
Strap / bracelet: 5-link stainless steel bracelet, T-fit clasp
Style: Dive

Movement

Caliber: Tudor MT5400-U
Type: automatic
Power reserve: 65 hours
Frequency: 28,800 vph (4 Hz)
Jewels: 27
Accuracy: COSC + METAS Master Chronometer

Takes 20 mm straps. See other 20 mm watches and straps.

More Black Bay 58 references

Watches that wear the same size

Other watches within 1.5 mm of its lug-to-lug.

Same 20 mm lug width

All 20 mm watches

These take the same straps as the Black Bay 58.