Since there are several common sizes of either filler material and consumable or non-consumable electrodes, here is a reference conversion table of imperial to metric. (Note, they're not perfect conversions, but how these values are typically used.)
|Fractions of inch (")||1000ths of inch (")||Metric (mm)|
Things to specify when ordering wire consumables:
Specification or classification of material.
Diameter of filler.
Length, for TIG rods, or spool size: D300 (12"), D200 (8"), D100 (4").
Amount of wire to be ordered, either in number of rods, spools or by weight.