International conversions Nov 21, 2026 4 min read
Watch Strap Size Conversion
Watch straps need two measurements: lug width (where strap meets case, in mm) and strap length. Apple Watch uses its own size system.
The Chart
| Wrist | Strap Length | Common Lug Widths |
|---|---|---|
| 5.5-6" | S | 18mm, 20mm |
| 6-6.5" | S/M | 18mm, 20mm, 22mm |
| 6.5-7" | M | 20mm, 22mm |
| 7-7.5" | M/L | 20mm, 22mm |
| 7.5-8" | L | 22mm, 24mm |
| 8-8.5" | L/XL | 22mm, 24mm |
| 8.5+" | XL | 24mm, 26mm |
FAQs
Lug width — how to measure?
Distance between the two lugs (where strap inserts into the case). Use a ruler or caliper, in mm. 18mm and 20mm are most common men's. 14mm-16mm for smaller women's watches.
Apple Watch sizing?
Apple Watch uses 38/40/41/42mm or 42/44/45/49mm case sizes. Bands sized S/M/L by wrist circumference. Bands work across same case size (40mm bands fit 38mm and 41mm cases).
Need this on your store?
Tailor Size Guide ships pre-built size charts for Shopify.