Wire speed ↔ amps

GMAW · solid wire on mild steel

Your machine has a wire speed dial. The procedure, the chart on the wall and every forum answer are in amps. This converts between them.

Wire diameter

Wire feed speed — 240 ipm

Approx. amperage

140 A

At this feed rate

Suggested voltage

19–22 V

Trim by ear and bead shape

Suits roughly

1/8 in steel

At about 1 A per 0.001 in

Why this isn't exact

The relationship between feed rate and current is close to linear for a given wire, but the constant moves with stickout, and that's the part nobody tells you. Longer stickout means more resistive preheating of the wire before it reaches the arc, so it burns off with less arc current — same dial setting, lower amps, less penetration. A change from 3/8 in to 3/4 in of stickout is worth more than most of the adjustments you'll make on the dial.

So treat the amperage here as "what a chart would call this setting", not as a measurement. If your machine has an ammeter, believe the ammeter.

Not sure whether it worked?

Numbers in, bead out. Bead Score scores the bead you actually laid and keeps it next to the settings that produced it, so over a few weeks you stop converting units and start reading your own log. Practice feedback, not an inspection.

Sources

Miller — MIG Welding: Setting the Correct Parameters, anchoring 0.035 in wire at 240–290 ipm against 140–175 A.
ESAB — MIG machine settings, on stickout and its effect on current.