MIG Settings Calculator
Mild Steel MIG Settings (ER70S-6, 75/25 Ar/CO2)
| Thickness | Amperage | Wire | Wire Speed | Voltage | Passes |
|---|---|---|---|---|---|
| 24 ga (0.024") | 27–33A | .023" | 94–116 ipm | 14.8–15.8 V | 1 pass |
| 22 ga (0.030") | 27–33A | .023" | 94–116 ipm | 14.8–15.8 V | 1 pass |
| 18 ga (0.048") | 43–53A | .023" | 151–185 ipm | 15.5–16.5 V | 1 pass |
| 16 ga (0.060") | 54–66A | .023" | 189–231 ipm | 16.0–17.0 V | 1 pass |
| 14 ga (0.075") | 68–82A | .030" | 135–165 ipm | 16.6–17.6 V | 1 pass |
| 11 ga (1/8") | 112–138A | .035" | 180–220 ipm | 18.8–19.8 V | 1 pass |
| 3/16" | 169–207A | .035" | 271–331 ipm | 21.4–22.4 V | 1 pass |
| 1/4" | 225–275A | .045" | 225–275 ipm | 24.0–25.0 V | 2+ passes, bevel |
| 5/16" | 281–343A | .045" | 281–343 ipm | 26.6–27.6 V | 2+ passes, bevel |
| 3/8" | 338–413A | .045" | 338–413 ipm | 29.2–30.2 V | 2+ passes, bevel |
Short-circuit transfer up to about 1/4". Thicker steel on a 240V machine is usually run in spray transfer with .045" wire and 90/10 argon/CO2 at higher voltage. ipm = inches per minute. Gas flow 25–35 CFH indoors.
Gas and Polarity by Process
| Process | Wire | Gas | Polarity | Drive Roll |
|---|---|---|---|---|
| Mild steel solid | ER70S-6 | 75% Ar / 25% CO2 (or 100% CO2 for deeper, rougher welds) | DCEP | V-groove |
| Self-shielded flux core | E71T-11 / E71T-GS | None | DCEN | Knurled |
| Dual-shield flux core | E71T-1 | 75/25 or 100% CO2 | DCEP | Knurled |
| Stainless | ER308L / ER316L | Tri-mix (90 He / 7.5 Ar / 2.5 CO2) or 98/2 Ar/CO2 | DCEP | V-groove |
| Aluminum | ER4043 / ER5356 | 100% Argon | DCEP | U-groove (spool gun recommended) |
Dialing In a MIG Welder
On most MIG machines you set two things: voltage and wire feed speed. Amperage is not a knob; it follows wire speed. Feed more wire and the machine pushes more current to melt it. Voltage controls the arc length and how flat the bead lies. Get the two in balance and the arc sounds like steady frying bacon.
Start With Thickness
The working rule for steel is about one amp per thousandth of an inch of thickness. 1/8" (0.125") steel wants roughly 125 amps. That gives you a wire speed for your wire diameter, and the chart gives you a voltage to pair with it. Run a test bead on scrap of the same thickness and joint, then adjust one setting at a time.
Reading the Arc
Voltage too low: the wire stubs into the plate and pushes the gun back, the bead is tall and narrow, and the toes do not wet in. Voltage too high: a long hissing arc, a wide flat bead, more spatter and undercut, and burn-through on thin sheet. Wire speed too high for the voltage feels like stubbing; too low burns back toward the tip and sputters.
Wire Diameter
.023" and .024" wire is for sheet metal and auto body, where low heat matters. .030" is the best all-rounder for 120V machines. .035" covers most 240V shop work from 16 gauge up through 1/4". .045" is for heavy plate and spray transfer. See the MIG wire size chart for the full breakdown and how long a spool lasts.
Shielding Gas Choice
75/25 argon/CO2 is the standard for mild steel: a stable arc, low spatter and good-looking welds. Straight CO2 is cheaper and digs deeper but spatters more. Self-shielded flux core (E71T-11) needs no gas at all, which is why it is the go-to outdoors where wind blows shielding gas away. Remember flux core runs electrode negative (DCEN), so swap the leads.
120V vs 240V Machines
A 120V MIG welder tops out around 125–140 amps. That handles up to about 3/16" in a single pass on steel, and 1/4" with a bevel and multiple passes. Anything thicker needs a 240V machine. If you are pushing a small welder near its limit, watch the duty cycle; at max output many 120V units only weld 20% of a ten-minute period.
Stainless and Aluminum
Stainless holds heat and warps easily, so run about 10% less current than steel and keep travel speed up. Aluminum is the opposite: it pulls heat away fast and needs more current per thickness, plus a spool gun or U-groove rolls and a Teflon liner so the soft wire does not birdnest. Push the gun (forehand) on aluminum; never drag it.
Technique Settings That Matter
Keep the contact tip 3/8" to 1/2" from the work (stickout) for short-circuit MIG; longer stickout drops the current and makes a cold, ropey bead. Hold the gun 10–15° from vertical. Pushing gives a flatter bead with less penetration; pulling digs deeper with a taller bead.
Frequently Asked Questions
Start around 115–135 amps with .030" or .035" ER70S-6 wire, about 200 inches per minute on .035" wire, roughly 19 volts and 75/25 argon/CO2 at 25–35 CFH. Run DCEP and adjust on scrap.
Use .023" for sheet metal and auto body, .030" for most work on a 120V welder, .035" for general shop work on a 240V machine up to about 1/4", and .045" for heavy plate.
No. Self-shielded flux core wire such as E71T-11 runs DCEN (electrode negative). Solid wire with gas runs DCEP. Swap the leads inside the machine when you change wire types.
The most common causes are voltage too high for the wire speed, wrong polarity, too much stickout, 100% CO2 gas, or dirty metal. Check polarity first, then bring voltage and wire speed back into balance.
About 3/16" steel in one pass, and 1/4" with a beveled joint and multiple passes. Flux core on a 120V machine can reach slightly thicker material than solid wire.
