How it works
The calculator uses three published rules of thumb for short-circuit MIG on carbon steel with solid wire:
- Amps: about 1 A per 0.001 in of thickness (Miller).
- Wire feed speed = amps × a factor for the wire size (Miller): 3.5 in/A for .023", 2 for .030", 1.6 for .035" and 1 for .045".
- Voltage ≈ 14 + 0.05 × amps. This is the conventional MIG load voltage from the welding power source standard IEC 60974-1. It’s a reasonable starting point, but real machines and gases vary, so expect to adjust by a volt or two.
MIG settings chart for mild steel
| Thickness | Amps | Wire | Wire speed | Voltage (est.) |
|---|---|---|---|---|
| 22 ga (0.030 in) | 30 | .023" | 105 in/min | about 15.5 V |
| 18 ga (0.048 in) | 48 | .030" | 96 in/min | about 16.4 V |
| 16 ga (0.060 in) | 60 | .030" | 120 in/min | about 17 V |
| 14 ga (0.075 in) | 75 | .030" | 150 in/min | about 17.8 V |
| 11 ga (0.120 in) | 120 | .030" | 240 in/min | about 20 V |
| 1/8 in (0.125 in) | 125 | .030" | 250 in/min | about 20.3 V |
| 3/16 in (0.188 in) | 188 | .045" | 188 in/min | about 23.4 V |
| 1/4 in (0.25 in) | 250 | .045" | 250 in/min | about 26.5 V |
Single-pass starting points with 75/25 gas. Most 120 V hobby welders top out around 125–140 A, so weld 3/16 in and thicker with a bevel and several passes, or use a 240 V machine. Not sure what your welder can handle on your power supply? Use the generator size calculator.
Shielding gas by metal
| Metal | Gas | Notes |
|---|---|---|
| Mild steel | 75% argon / 25% CO₂ (C25) | The all-round choice: smooth arc, little spatter |
| Mild steel | 100% CO₂ | Cheaper and deeper penetration, but more spatter |
| Stainless steel | 98% argon / 2% CO₂ or O₂, or a tri-mix | Don’t use C25 on stainless |
| Aluminum | 100% argon | Needs a spool gun or push-pull gun and different settings |
Fine-tuning on scrap
- Stick-out: keep about 3/8–1/2 in of wire past the contact tip for short-circuit MIG.
- Listen: a good short-circuit arc sounds like bacon frying. Popping and stubbing means too little voltage; a hissing, wandering arc means too much.
- Change one thing at a time: set wire speed for the heat you need, then adjust the voltage to suit it.
- Flux-core wire runs on DCEN (electrode negative) with no gas. Use the wire maker’s chart, because these rules are for solid wire.
New to MIG? See our guide to welding processes and welding joints.
Sources: Miller Electric, “MIG Welding: Setting the Correct Parameters”; ESAB University, MIG machine settings guide (gas flow, stick-out and gas choice); IEC 60974-1 conventional load voltage for MIG/MAG.
FAQ
What MIG settings should I use for 1/8 inch steel?
Start at about 125 A. With .030 in wire that is about 250 in/min wire feed speed; with .035 in wire, about 200 in/min. Use 75/25 argon/CO₂ and fine-tune the voltage until the arc sounds like a steady sizzle.
How many amps do I need to MIG weld?
A common rule of thumb is 1 amp for every 0.001 in of steel thickness: about 60 A for 16 gauge, 125 A for 1/8 in and 190 A for 3/16 in, in a single pass.
What size MIG wire should I use?
.023–.024 in for thin sheet metal, .030 in for general hobby work up to about 3/16 in, .035 in for thicker steel on 180–250 A machines, and .045 in for heavy plate on industrial machines.
How do I know if my voltage is too high or too low?
If the wire stubs into the metal and pushes the gun back, the voltage is too low (or the wire speed too high). If the arc is long, erratic and burns back toward the tip with a lot of spatter, the voltage is too high.
What gas flow rate should I use for MIG?
About 20–30 cfh (10–15 L/min) indoors. More is not better: too much flow causes turbulence that pulls air into the weld.