Seiko Watch Strap Sizes
Lug width and strap fitting for every Seiko model in our index. Tap a watch for the full guide.
Across the 18 Seiko models with standard lugs in our index, lug widths are 18mm (1), 20mm (10), 22mm (7). The most common is 20mm, but don't assume: sizes vary within the brand, so check your exact model below. 6 use fat 2.5mm spring bars, so thick rubber and NATO straps suit them (why that matters).
Seiko lug width chart
| Model | Reference | Strap size | Case | Lug-to-lug |
|---|---|---|---|---|
| SKX007 / SKX009 | 7S26-0020 | 22mm | 42.5mm | 46mm |
| SKX013 | SKX013 | 20mm | 38mm | 44mm |
| 5 Sports (5KX) | SRPD51 | 22mm | 42.5mm | 46mm |
| Prospex Turtle | SRP777 | 22mm | 45mm | 48mm |
| Samurai | SRPB51 | 22mm | 43.8mm | 47mm |
| Prospex 62MAS | SPB143 | 20mm | 40.5mm | 47.2mm |
| Prospex Willard | SPB153 | 20mm | 42.7mm | 47.9mm |
| Marinemaster 300 | SBDX017 | 20mm | 44.3mm | 51mm |
| Alpinist | SARB017 | 20mm | 39mm | 46mm |
| SARB033 | SARB033 | 20mm | 38mm | 44mm |
| Presage Cocktail Time | SRPB41 | 20mm | 40.5mm | 47.6mm |
| Seiko 5 (SNK) | SNK809 | 18mm | 37mm | 43.5mm |
| Prospex Sumo | SPB103 | 20mm | 45mm | 52.6mm |
| 5 Military (SNZG) | SNZG13 / SNZG15 | 22mm | 42mm | — |
| Prospex Monster (SRPD27) | SRPD27 | 20mm | 42.4mm | — |
| 5 Sports GMT (SSK001) | SSK001 | 22mm | 42.5mm | 46mm |
| Prospex Alpinist (SPB121) | SPB121 | 20mm | 39.5mm | 46.4mm |
| Prospex King Turtle (SRPE03) | SRPE03 | 22mm | 45mm | 47.7mm |
Strap size = lug width. Not sure which model you have? Measure it or see the strap size chart for every brand.