IEC 60228

IEC 60228 is the International Electrotechnical Commission (IEC)'s international standard on conductors of insulated cables. As of 2023 the current version is Third Edition 2004-11 Among other things, it defines a set of standard wire cross-sectional areas:

0.5 mm
0.75 mm
1 mm
1.5 mm
2.5 mm
4 mm
6 mm
10 mm
16 mm
25 mm
35 mm
50 mm
70 mm
95 mm
120 mm
150 mm
185 mm
240 mm
300 mm
400 mm
500 mm
630 mm
800 mm
1000 mm
1200 mm
1400 mm
1600 mm
1800 mm
2000 mm
2500 mm

In engineering applications, it is often most convenient to describe a wire in terms of its cross-section area, rather than its diameter, because the cross section is directly proportional to its strength and weight, and inversely proportional to its resistance. The cross-sectional area is also related to the maximum current that a metallic wire can carry safely.

This document is one considered fundamental in that it does not contain reference to any other standard.