Chain Size Grade 30 BBB

Width Length
Chain size Diameter
A
Outer
B
Inner
C
Outer
D
Pitch
E
mm in mm in mm in mm in mm in
1/4in 7.1 0.281 25.1 0.990 10.9 0.430 36.3 1.430 22.1 0.870
5/16in 8.7 0.343 30.2 1.190 12.7 0.500 43.0 1.691 25.4 1.000
3/8in 10.3 0.406 36.3 1.430 15.7 0.620 48.3 1.901 27.7 1.090
1/2in 13.5 0.531 46.0 1.810 19.1 0.750 61.0 2.401 34.0 1.340

Source: http://coxeng.co.uk/anchoring/chain/