Every strap question about a Rolex starts with one number: the lug width, the distance in millimeters between the lugs where the strap sits. Get it right and a strap looks factory-fitted; miss it by a single millimeter and nothing sits properly. The catch is that Rolex has never used just one width — and some families changed width between generations, so a strap from your old watch won't necessarily fit your new one.
This page is the master reference. It's built from the fit research behind our sixty-plus individual Rolex strap guides, and it covers the three widths that dominate the catalog, family by family. Two notes before the numbers: every Helvetus strap is made for a specific model, so on most collection pages there's nothing to select — if it's in your watch's collection, it fits. And where a collection serves several widths, the product page carries a simple selector. When in doubt, the Strap Finder routes you to the right collection in two clicks.
20mm – the classic Rolex width
The width of the 36mm Oyster case, and the biggest group in the catalog:
Datejust 36 — every generation. From the 1601 of the sixties through the five-digit references, the six-digit era and today's models, the Datejust 36 has stayed a 36mm case with a 20mm lug width. Everything in the Datejust 36 collection fits every generation.
Every Turn-O-Graph "Thunderbird." All of them — from the fifties originals through the 16250/16253/16258 trio, the 16263/16264 generation and the six-digit models — are built on the Datejust 36 case. Same 20mm width, same collection as above.
Day-Date 36 — every generation. The 36mm President has been 20mm from the vintage 1803 through the 18038, 18238, 118238 and today's 128238/128239. One Day-Date 36 collection serves them all.
Day-Date 40 — every reference. Despite the bigger 40mm case, the modern Day-Date 40 (all 228xxx references, 2015 to today) uses a 20mm lug width. The Day-Date 40 collection covers the full range, every metal.
Oyster Perpetual 36 and 39. The OP 36 (116000, 126000 — including the colored dials) is 20mm; so is the discontinued OP 39 (114300). Their collections: Oyster Perpetual 36 and Oyster Perpetual 39.
Vintage and neo-vintage Explorer. The classic 36mm Explorers — 1016, 14270, 114270 — and the 39mm 214270 all take 20mm. (The modern Explorers changed; see the decoder below.)
21mm – the modern sports width
Rolex's width for the current large-case generation. If your watch is on this list, note the important part: your 20mm straps won't fit it.
Datejust 41 — all references. The 41mm Datejust (126300, 126334 and siblings) is a 21mm watch.
Oyster Perpetual 41. Both the 124300 and the new 134300 that replaced it in 2025 take 21mm.
Day-Date II. The 2008–2015 41mm President (all 218xxx references) is 21mm — one millimeter and one digit away from the Day-Date 40, and the single most common mix-up in the President family. If your reference starts with 218, you need the Day-Date II collection, not the Day-Date 40 one.
Explorer 40. The current 224270 (2023–) is the first 21mm Explorer — no strap from any earlier Explorer carries over.
The current Submariner. The 41mm Submariner generation shares its 21mm width with the Datejust 41 — one of the reasons this width now defines modern Rolex.
19mm – the outlier
Explorer 36 (124270). The current 36mm Explorer, launched 2021, took the family down to 19mm — unique among the models on this page. Which brings us to the family that needs its own map:
The Explorer decoder
No Rolex family has changed width more than the Explorer, so here it is in one place: the 1016, 14270, 114270 and 214270 are 20mm · the current 36mm 124270 is 19mm · the current 40mm 224270 is 21mm. Three widths across one model name — every strap in the Explorer I collection carries a width selector (19/20/21mm) so one collection can serve all six generations. Select your watch's width, and nothing else transfers between them.
Families with a model selector
A few collections serve references that differ from each other, so the product page asks which watch you have — no measuring required:
Air-King: choose your model (116900 or 126900) on the product page. Explorer II: generations differ; select your model when ordering. Submariner (earlier generations), Daytona, GMT-Master II, Yacht-Master, Yacht-Master II, Sea-Dweller, Sky-Dweller, Milgauss: every product page in these collections states its exact fit, and each has its own dedicated strap guide on this blog with the full sizing story. The fastest route to any of them is the Rolex collection overview or the Strap Finder.
And one for the future: the Land-Dweller collection is in development — straps engineered for the new case are on the way.
The traps worth knowing
Three mistakes cause most wrong orders, and all three are avoidable in ten seconds:
The President one-digit trap. 128238 (36mm, 20mm), 228238 (40mm, 20mm) and 218238 (41mm, 21mm) are three different watches. Same for 228206 vs 218206. Check the first three digits of your reference before ordering.
The Explorer generation trap. As above — 19, 20 and 21mm all exist in one family. Your old Explorer strap fitting your new Explorer is the exception, not the rule.
The upgrade trap. Moved from a Datejust 36 to a 41? From an older Submariner to the current one? Your strap drawer didn't move with you — the modern large cases are 21mm.
Quick answers
How do I measure lug width myself? Measure the straight-line distance between the inside faces of the lugs, in millimeters, where the spring bar sits. On Rolex models it will land on 19, 20 or 21mm for everything covered above.
My model isn't listed — now what? Its collection and product pages state the exact fit, and the Strap Finder narrows it by brand and model. Support can confirm any edge case.
Do Datejust 36 straps fit my Thunderbird / Day-Date 36 straps fit every President generation? Yes and yes — those cases never changed width. That's the quiet advantage of the 20mm classics: one collection, every generation.
Want the full story on your exact reference? That's what the individual guides are for — for example the Day-Date 36 18238, Day-Date 40 228239, Oyster Perpetual 36 126000, Oyster Perpetual 41 124300, and the Explorer trio (14270, 214270, 124270) — with sixty more across the blog.
One number, then the fun part
Once the width is right, everything else is taste. Every Helvetus strap is precision-made for its exact Rolex model — correct width, curved fit, spring bars included — with a lifetime warranty on all rubber, free worldwide shipping and no import costs, trusted by over 50,000 customers. Find your width above, open your collection, and pick a color. The hard part took you ninety seconds.
