MIG Wire Feed Speed Calculator
Convert a target MIG amperage and wire diameter into a wire feed speed in inches and metres per minute as a starting setting.
How it works
WFS (in/min) ≈ 0.001515 × amps ÷ wire cross-section area · area = π × d² ÷ 4 · m/min = in/min × 25.4 ÷ 1000
On a constant-voltage MIG machine the current follows the wire feed speed, so setting the feed rate is really how you set amperage. Thinner wire needs a faster feed to carry the same current because there is less cross-section to melt, which is why the formula divides by wire area. The result is a solid starting point — thin the arc by ear and by bead appearance, and always cross-check your machine’s chart for the wire and gas you run.
Worked example
For 0.035-inch wire at 200 A: area = π × 0.035² ÷ 4 = 0.000962 in²; WFS = 0.001515 × 200 ÷ 0.000962 ≈ 315 in/min, about 8.0 m/min. Drop to 0.030-inch wire and the same 200 A needs a faster feed.
Frequently asked questions
Is wire feed speed the same as amperage?
On a CV MIG welder they move together — raising the feed speed raises the current draw. That is why many machines let you dial in wire speed directly and read amperage as a result.
Why does thinner wire feed faster?
A thinner wire has less cross-sectional metal, so more length must feed into the arc each minute to melt off the same amount of filler and carry the same current.
Does voltage change the wire feed speed I need?
Voltage sets arc length and bead profile, not the feed-to-current relationship directly. Set wire speed for the target current first, then adjust voltage for a smooth, quiet arc.
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This calculator is for educational purposes. Double-check important results before acting on them.