Rolex Submariner lug width: 21 mm today, 20 mm before 2020
Founder & CEO, Smartlet - CentraleSupelec engineer - Concours Lepine 2025, Awarded - CES 2026
Contents
The Rolex Submariner has a 21 mm lug width since the 41 mm generation launched in 2020, and 20 mm on the 40 mm models made before it. One millimetre sounds like nothing. On a strap, it decides between a snug fit and a gap you can see from across the table, which is why the question keeps coming back every time someone buys a Submariner second hand.
- 41 mm models, from 2020. Lug width 21 mm, on both the Submariner and the Submariner Date.
- 40 mm models, before 2020. Lug width 20 mm.
- The quick test. Measure the inside distance between the lugs with a caliper. 21 mm or 20 mm, nothing in between.
- Shorter lugs too. The 2020 case has shorter, more tapered lugs, 26.7 mm against 27.5 mm.
- On a Smartlet. The watch adapters are chosen at order: 21 mm for a current Submariner, 20 mm for an older one.
Submariner lug width by generation
| Generation | Case | Lug width | Lug length | Movement |
|---|---|---|---|---|
| From 2020 | 41 mm | 21 mm | 26.7 mm | Calibre 3230 (no date), 3235 (Date) |
| Before 2020 | 40 mm | 20 mm | 27.5 mm | Calibre 3130 (no date) |
Sources: Monochrome Watches and Watchonista on the 2020 Submariner. Both cases are about 12.5 mm thick and rated to 300 m, so neither the profile nor the depth rating tells them apart. The lugs do.
The 21 mm figure is also what the Smartlet reference base lists for current references, with 20 mm for earlier ones.
How to tell which Submariner you have
The case size gives the honest answer, and the hardest one to see with the naked eye: 41 against 40 mm. Two easier checks:
- Look at the year on the warranty card. 2020 or later, with a 41 mm case, means 21 mm.
- Measure the gap between the lugs with a caliper, inside edge to inside edge. While you are there, look at the lugs: the 2020 case has visibly slimmer, more tapered ones.
If you have never measured a lug width before, what lug width is, and how to measure yours walks through it, and the lug width finder has both Submariner generations.
A 20 mm strap on a 21 mm Submariner leaves a gap on each side and lets the spring bars show. A 21 mm strap will not go into a 20 mm case at all. Measure before you buy.
Why Rolex added a millimetre
The 2020 case grew by a millimetre, and Rolex widened the lugs and the bracelet with it, while shortening and tapering the lugs so the watch wears no bigger on the wrist. In photographs, the two generations look almost identical.
For owners, the practical effect is narrower: the strap you bought for a 40 mm Submariner does not fit the 41 mm one properly. Check the width before you order one.
The Submariner on a Smartlet
The Submariner uses standard spring bars, which is what the Smartlet needs. The Oyster bracelet comes off with the spring bar tool included in the box, and two watch adapters take the place of the spring bars: 21 mm for a current Submariner, 20 mm for an older one. The width is chosen at order, which is why the measurement above matters.
The Submariner then sits on top of the wrist, and a smartwatch or sensor sits underneath, against the skin, in the central part of the bracelet: an Apple Watch or a Whoop, among other compatible smartwatches.
For a Submariner, having the first installation done by a watchmaker is a sensible precaution. After that, with watch adapters fitted, switching watches takes under 5 seconds.
Every Rolex family with its lug widths is on the Rolex compatibility page, and the setup itself is on set up your Smartlet.
Smartlet, awarded at the Concours Lepine 2025 and selected for CES 2026: see the Smartlet One collection.
