Longines
Longines Spirit 40 Strap Size — 21mm Lug Width
The Longines Spirit 40 has a 21mm lug width, so it takes a 21mm watch strap.
Lug width21mm
| Lug width | 21 mm |
|---|---|
| Case size | 40 mm |
| Lug-to-lug | 47 mm |
| Thickness | 12.6 mm |
| Spring bar Ø (typical) | 2.0 mm |
| End type | Fitted ends best |
Which reference do you have?
Similar-looking models can take different straps. Your reference number is on the case back or your papers.
| Model | Case | Strap |
|---|---|---|
| Spirit 40 (L3.810) | 40mm | 21mm |
| Spirit 42 and Spirit chronographs | 42mm | Check your reference |
Strap styles that fit
- NATO / Zulu21mm fits if the strap's thickness clears the case under the bars.
- PerlonWoven pass-through, 21mm.
- 2-piece leatherStraight ends fit; curved ends for a gapless look.
- Rubber / siliconeDivers & sports fit well.
- Milanese / meshStraight-end 21mm mesh fits.
- Metal braceletNeeds 21mm end-links shaped for this case.
▲ 21mm on the 40mm (L3.810) references.
Fit & sizing notes for the Spirit 40
- Width: buy 21mm straps. Tapered straps listed as 21/19mm or 21/17mm fit too; only the first number has to match. See strap sizes explained.
- Spring bars: 21mm long, about 2.0mm diameter (spring bar sizes).
- Odd size: 21mm straps are harder to find; a 20mm strap fits with a small gap, but never go wider. Odd lug width options.
- Ends: the case curves between the lugs, so curved or fitted-end straps close the gap. Straight-end straps still fit.
- Wrist fit: at 47mm lug-to-lug it should sit within the top of wrists from about 15.7cm up (rule of thumb: lug-to-lug under ~30% of wrist size). That's longer than 36% of the watches in our index. See what size watch suits your wrist.
- Strap thickness: at 12.6mm thick it's a chunky case: thicker padded leather, rubber/FKM or a heavier NATO balance it visually; very thin straps can look undersized.
Sources & corrections
Correction, 24 October 2026: This page previously listed 20mm. The 40mm Spirit (L3.810) is 21mm.
Lug width checked against: WatchBase: Spirit 40 L3.810. Last checked 24 October 2026.
Spec wrong for your watch? Send us a correction with your reference number.
Get the right strap
Links open Amazon — we may earn a commission at no cost to you.
Longines Spirit 40 — strap questions
What size strap does the Spirit 40 take?
The Longines Spirit 40 has a 21mm lug width, so you need a 21mm watch strap.
Will any 21mm strap fit the Spirit 40?
Most will. Width is the main thing to match, but also check that the strap's spring-bar holes suit the bars, and that the strap is thin enough to clear the case between the lugs. For a gapless look, pick curved/fitted ends. A metal bracelet needs 21mm end-links made for this model.
What spring bar size does the Spirit 40 use?
21mm long and about 2.0mm in diameter (a typical figure; measure the original bar to be sure).
Is the Spirit 40 good for strap swapping?
Yes. With standard 21mm spring-bar lugs, NATO, leather, rubber and mesh straps can all be fitted with a spring-bar tool.