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Omega · Speedmaster

Omega Speedmaster Calibre 321

Reference 311.30.40.30.01.001 · Chronograph · 39.7 mm

50030020015012010090807060Ø 39.7 mmLug-to-lug 48 mm
Illustration drawn from the specifications: case to scale, colours and style approximate. Not a photo. Photos on the official page

Specifications

Reference
311.30.40.30.01.001
Family
Speedmaster
Category
Chronograph
Status
Current
Case material
Stainless steel
Case diameter
39.7 mm
Case thickness
13.7 mm Official
Lug-to-lug
48 mm Official
Lug width
19 mm Official
Water resistance
50 m
Bezel
Fixed, tachymetric scale
Calibre
321 Official
Power reserve
55 h
Frequency
18,000 vph (2.5 Hz)

Official product page · retrieved October 14, 2026

Does it fit your wrist?

Enter your wrist circumference. The watch appears to scale on the flat top of the wrist.

50030020015012010090807060Lug-to-lug 48 mmFlat top of the wrist 54.1 mm
Top view on a wrist, to scale
Flat top of the wrist 54.1 mmLug-to-lug 48 mmCase diameter 39.7 mm
Side view, across the wrist

Comfortable

Lug-to-lug 48 mm on a flat top of 54.1 mm: 89 % of the width.

Lug-to-lug is 75 to 95% of the flat top, the usual comfortable range.

Measurements and sources

Brands rarely publish thickness, lug width and lug-to-lug together. Each observation below is kept separate, with who gave it.

Case thickness

Value Type Source Date
13.7 mm Official Omega October 14, 2026

Lug-to-lug

Value Type Source Date
48 mm Official Omega October 14, 2026

Lug width

Lug width is the gap between the lugs, where the strap fits. It is not lug-to-lug.

Value Type Source Date
19 mm Official Omega October 14, 2026

Calibre source

Official Omega · retrieved October 14, 2026

Other Speedmaster references

Watch Ø Thickness Lug-to-lug Calibre
Speedmaster First OMEGA in Space 310.30.40.50.06.001 39.7 mm 13.4 mm 48 mm 3861
Speedmaster '57 40.5 mm 332.10.41.51.01.001 40.5 mm 13 mm 49.6 mm 9906
Speedmaster 38 mm 324.30.38.50.02.001 38 mm 14.7 mm 44.9 mm 3330
Speedmaster Moonwatch Professional (Hesalite) 310.30.42.50.01.001 42 mm 13.5 mm 47.5 mm 3861
Speedmaster Moonwatch Professional (sapphire) 310.30.42.50.01.002 42 mm 13.2 mm 47.5 mm 3861
Speedmaster Chronoscope 43 mm 329.30.43.51.02.002 43 mm 12.8 mm 48.6 mm 9908
Speedmaster Moonphase 44.25 mm 304.30.44.52.01.001 44.25 mm 16.9 mm 50 mm 9904
Speedmaster Super Racing 329.30.44.51.01.003 44.25 mm 14.9 mm 50 mm 9920
Speedmaster Apollo 8 310.92.44.50.01.001 44.25 mm 13 mm 50 mm 3869
Speedmaster Dark Side of the Moon 44.25 mm 310.92.44.51.01.001 44.25 mm 13 mm 50 mm 9908

Other Omega models

Watch Ø Thickness Lug-to-lug Calibre
Seamaster Railmaster 38 mm 235.12.38.20.06.001 38 mm 12.4 mm 44.9 mm 8806
Seamaster Railmaster 40 mm 220.10.40.20.01.001 40 mm 12.7 mm 47 mm 8806
Seamaster 300 41 mm 234.30.41.21.01.001 41 mm 13.9 mm 48 mm 8912
Seamaster Diver 300M 42 mm 210.30.42.20.01.001 42 mm 13.6 mm 49.9 mm 8800
Seamaster Planet Ocean 600M 42 mm 217.30.42.21.01.003 42 mm 13.8 mm 47.5 mm 8912
Seamaster Planet Ocean 600M 39.5 mm 215.30.40.20.01.001 39.5 mm 14.2 mm 45.6 mm 8800
Show 9 more
Watch Ø Thickness Lug-to-lug Calibre
Seamaster Aqua Terra 150M GMT Worldtimer 43 mm 220.10.43.22.03.001 43 mm 14.1 mm 50.3 mm 8938
Constellation Observatory 39.4 mm 140.13.39.21.02.001 39.4 mm 12.2 mm 47.2 mm 8914
Constellation 41 mm 131.30.41.21.04.001 41 mm 13.5 mm 44 mm 8900
De Ville Prestige 41 mm 434.13.41.21.03.002 41 mm 10.8 mm 47.9 mm 8810
Seamaster Planet Ocean Ultra Deep 45.5 mm 215.92.46.21.01.001 45.5 mm 18.1 mm 56 mm 8912
Seamaster Planet Ocean 600M 43.5 mm 215.30.44.21.01.001 43.5 mm 16.1 mm 49 mm 8900
Seamaster Planet Ocean 600M GMT 43.5 mm 215.30.44.22.01.001 43.5 mm 17 mm 49.4 mm 8906
Seamaster Aqua Terra 150M 41 mm 220.10.41.21.03.001 41 mm 13.2 mm 47.9 mm 8900
Seamaster Aqua Terra 150M 38 mm 220.10.38.20.03.001 38 mm 12.2 mm 45 mm 8800

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