Individual wire (plain and deformed) size designations are based on the cross-sectional area of a given wire. Gage numbers were used exclusively for many years but were eliminated in the 1970’s to reduce the confusion caused from the misunderstanding of how to read and understand the specified gage size. The prefixes “W” and “D” are used in combination with a number. The letter “W” designates a plain wire and the letter “D” denotes a deformed wire. The number following the letter gives the cross-sectional area in hundredths of a square inch. For instance, wire designation W4 would indicate a plain wire with a cross-sectional area of 0.04 in2; a D10 wire would indicate a deformed wire with a cross-sectional area of 0.10 in2. The size of wires in WWR is designated in the same manner. This system provides many advantages. Since the engineer knows the cross-sectional area of a wire and the spacing, the total cross-sectional area per foot of width can easily be determined. For instance, a D6 wire on 4” centers would provide 3 wires per foot with a total cross-sectional area of 0.18 in2/ft of width.

When describing metric wire the prefix “M” is added. “MW” describes metric plain wire and “MD” metric deformed wire. The wire spacing in metric WWR is given in millimeters (mm) and the cross-sectional area of the wire is in square millimeters (mm2).