Blancpain Fifty Fathoms

Most Blancpain Fifty Fathoms references take a 23 mm watch strap: 83 of 115. The lug width follows the case size: 38 mm case → 20 mm, 43 mm case → 23 mm, 44 mm case → 23 mm and 45 mm case → 23 mm.

Shop 20 mm Shop 22 mm Shop 24 mm

Blancpain Fifty Fathoms lug width by case size

115 references measured. Updated 2026-10-29.

Case	Lug width	References	Watch strap attachment	For example
38 mm	20 mm	11	—	5100-1127-NAH, 5100-1127-NAJ, 5100-1127-NAT
40 mm	20 mm	8	—	5008-1130-71S, 5008-1130-B52A, 5008-1130-NABA
43 mm	23 mm	25	—	5000-1110-70B, 5000-1110-B52A, 5000-1110-K52A
44 mm	23 mm	10	—	5000-0130-B52A, 5000-0130-NABA, 5000-0240-NAOA
45 mm	23 mm · 24 mm on 1	40	—	5015-1127-52A, 5015-1130-52A, 5015-1130-71S
48 mm	24 mm	4	—	50015-12B30-52B, 50015-12B34-52B, 50015A-12B30-52B
not recorded	23 mm · 22 mm on 5 · 20 mm on 3	17	—	5000-1110-71S, 5025-12B40-98S, 5025-36B40-O52B

References that take a different watch strap

5015-12B30-B52A: 24 mm, not the 23 mm of most 45 mm cases
5010-12B30-98S: 22 mm
5010-12B30-B64B: 22 mm
5100-1130-63A-2019: 20 mm
Fifty Fathoms 70th Anniversary Act 1 Series I: 22 mm
Fifty Fathoms 70th Anniversary Act 1 Series II: 22 mm
Fifty Fathoms 70th Anniversary Act 1 Series III: 22 mm
Fifty Fathoms 70th Anniversary Act 3: 20 mm
Fifty Fathoms Ocean Commitment III: 20 mm

Questions about the Blancpain Fifty Fathoms

Do all Blancpain Fifty Fathoms case sizes take the same watch strap?

No. The lug width changes with the case size: the 38 mm case takes 20 mm, the 40 mm case takes 20 mm, the 43 mm case takes 23 mm, the 44 mm case takes 23 mm and the 45 mm case takes 23 mm. Check your case diameter before you buy.