The Tack Box · Welding Settings

TIG welding amps to metal thickness chart

TIG gives you the most control of any arc process. You run the heat with a foot pedal, feed filler by hand, and shield with pure argon. It is slower than MIG, but the bead quality is hard to beat on anything from mild steel to aluminum. This chart covers mild steel, stainless, and aluminum with tungsten sizing, filler rod diameter, cup size, and gas flow for every common thickness. All settings assume 100% argon shielding gas.

Quick answer

1/4 inch mild steel TIG: 150–200 A, DCEN, 3/32" 2% lanthanated (blue band) tungsten, 1/8" ER70S-2 filler, #8–#10 cup, 20–25 CFH argon.

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How to read this chart

Pick your metal, then read across the row for your thickness. For mild steel the rule of thumb is ~1 amp per 0.001″ of thickness, so 1/8" plate (0.125") starts near 125 amps, inside the 80–130 A on that row. Set your machine to the top of the range and let the pedal bring it down. Stainless takes a little less heat and aluminum on AC takes more.

Printable TIG (GTAW) chart

The same tables as this page on a letter-size PDF, with the sources printed at the bottom. Tape it up next to the machine.

TIG mild steel settings

Polarity: DCEN (DC−) · Filler: ER70S-2 · Gas: 100% Argon · Rule of thumb: ~1 amp per 0.001″ of thickness

ThicknessAmpsTungstenFiller RodCupGas Flow
0.035–0.059"30–501/16"0.040"#4–#610–15 CFH
0.060–0.120"50–901/16"1/16"#5–#715–20 CFH
1/8"80–1301/16"3/32"#6–#815–20 CFH
3/16"120–1803/32"1/8"#7–#820–25 CFH
1/4"150–2003/32"1/8"#8–#1020–25 CFH
3/8"200–2801/8"3/16"#8–#1020–30 CFH

TIG stainless steel settings

Polarity: DCEN (DC−) · Filler: ER308L / ER316L · Gas: 100% Argon · Rule of thumb: 10–15% less than mild steel at the same thickness

ThicknessAmpsTungstenFiller RodCupGas Flow
0.035–0.059"25–451/16"0.040"#4–#610–15 CFH
0.060–0.120"45–801/16"1/16"#5–#715–20 CFH
1/8"70–1151/16"3/32"#6–#815–20 CFH
3/16"100–1601/16"1/8"#7–#820–25 CFH
1/4"130–1803/32"1/8"#8–#1020–25 CFH
3/8"170–2501/8"3/16"#8–#1020–30 CFH

Stainless is more sensitive to heat than mild steel. Keep your travel speed up and use a gas lens to extend your shielding. Back-purge the root side on anything you care about. Stainless sugars fast.

TIG aluminum settings

Polarity: AC · Filler: ER4043 / ER5356 · Gas: 100% Argon · Rule of thumb: ~1–1.25 amps per 0.001″ on AC; start low on an inverter

ThicknessAmpsTungstenFiller RodCupGas Flow
1/16"60–1001/16"1/16"#5–#615–20 CFH
3/32"90–1251/16"3/32"#6–#715–20 CFH
1/8"120–1603/32"3/32–1/8"#7–#815–20 CFH
3/16"160–2203/32"1/8"#820–25 CFH
1/4"210–2751/8"5/32–3/16"#8–#1020–30 CFH

Aluminum requires AC polarity. The EN half of the cycle provides penetration, the EP half cleans the oxide layer off the surface. Set your AC balance to 65–75% EN for most work. Use a pure or balled tungsten tip, or a ceriated/lanthanated electrode with a rounded point.

Tungsten electrode sizing chart

Rated amperage by diameter for 2% lanthanated, ceriated, or thoriated tungsten in argon (Miller’s table, built from AWS and electrode maker data). DCEN is for steel and stainless. AC is for aluminum at about 65% EN balance. The charts above use the smallest size rated for the top of each amp range.

DiameterDCEN RangeAC Range
1/16" (1.6 mm)50–160 A50–150 A
3/32" (2.4 mm)135–235 A130–250 A
1/8" (3.2 mm)250–400 A225–360 A
5/32" (4.0 mm)400–500 A300–450 A
3/16" (4.8 mm)500–750 A400–500 A

Tungsten color codes

Band colors per AWS A5.12. Check the band, not the box: the 2009 edition moved ceriated from orange to gray, so older stock can still be orange.

TypeAWSBandNotes
2% lanthanatedEWLa-2blueStarts easy, holds a point, runs AC and DC. Good one-tungsten shop choice.
1.5% lanthanatedEWLa-1.5goldClosest drop-in for 2% thoriated.
1% lanthanatedEWLa-1blackLower oxide content, same family.
2% ceriatedEWCe-2grayGood low-amp starts on DC and inverter AC. Older stock is orange.
2% thoriatedEWTh-2redRuns well on DC, but thorium is mildly radioactive. Grinding dust is the concern.
Pure tungstenEWPgreenBalls up on AC. For older transformer machines on aluminum.
ZirconiatedEWZr-1brownAC on transformer machines. Resists spitting into the puddle.

Polarity guide

  • DCEN (DC electrode negative). Used for mild steel and stainless. The electrode stays cool, the work gets most of the heat. Gives deep penetration with a narrow bead profile.
  • AC (alternating current). Required for aluminum. The EP half-cycle breaks up the aluminum oxide layer that melts at 3,700 °F while the base metal melts at 1,220 °F. Without AC cleaning action, the weld puddle never wets out.
  • DCEP (DC electrode positive). Do not use DCEP for TIG. All the heat goes into the tungsten instead of the work. The electrode overheats and contaminates the weld. DCEP is for MIG and stick, not TIG.

Cup size and gas flow

  • Cup number = ID in 1/16" increments. A #8 cup has a 8/16" (1/2") inside diameter. A #10 cup is 10/16" (5/8"). Bigger cup = wider gas coverage = better shielding on larger welds.
  • Gas lens rule of thumb: a gas lens straightens the argon flow and lets you extend your tungsten further from the cup without losing coverage. With a gas lens, you can often drop your flow rate 5 CFH and still get better shielding than a standard collet body at higher flow. Use a gas lens on anything that matters.
  • Flow rate: start at 15–20 CFH for most work. Too much gas creates turbulence that pulls in atmosphere. More is not better. If you are welding outdoors or in a drafty shop, use a bigger cup and a gas lens rather than cranking the flow.

Questions welders keep asking

What size tungsten for 1/4 inch steel?

3/32" (2.4 mm) for 1/4 inch mild steel. It is rated to 235 A on DCEN, which covers the 150–200 A you need on 1/4 inch. Grind the taper about 2.5 times the diameter long. If you are pushing past 235 A, or the point keeps melting back, step up to 1/8".

AC or DC for aluminum TIG?

Always AC. Aluminum has an oxide layer that melts at 3,700 degrees F, way above the base metal at 1,220 degrees F. The EP half of the AC cycle blasts through that oxide. Without it, the filler balls up on the surface and never wets in. Set your AC balance to 65–75% EN for the best mix of cleaning and penetration.

How much argon flow for TIG welding?

15–25 CFH covers most shop work. Start at 15 CFH for thin material with a #5 or #6 cup, and go up to 25 CFH for 1/4 inch and thicker with a #8 or #10 cup. If you are getting porosity, check for drafts and leaks before turning up the gas. Too much flow causes turbulence that pulls in atmosphere. A gas lens lets you run lower flow with better coverage.

Lanthanated vs thoriated tungsten, which one?

Lanthanated for most shops. It starts easy, holds a point, and runs both AC and DCEN. 2% lanthanated is the blue band and 1.5% lanthanated is the gold band. 2% thoriated (red band) was the standard for decades and runs great on DC steel and stainless, but thorium is mildly radioactive and the grinding dust is the real concern. 2% ceriated (gray band, orange on older stock) is another non-radioactive option that starts well at low amps. If you only want to stock one type, go 2% lanthanated.

How do I size TIG filler rod?

Pick filler by the thickness you are welding, not by the tungsten. The charts above list a starting rod size for each thickness, roughly 1/16" on sheet, 3/32" on 1/8 plate, and 1/8" on 3/16 to 1/4 plate. Go one size smaller for more control on thin material or one size larger for faster fill on thick joints. A rod that is too big chills the puddle. One that is too small melts off before it reaches it.

What gas do I need for TIG welding?

100% argon covers nearly all TIG work: steel, stainless, and aluminum. Buy welding grade (99.995% pure). There are two TIG mixes worth knowing. Argon/helium adds heat for thick aluminum and copper. Argon with a few percent hydrogen is for austenitic (300 series) stainless only. What you never run on TIG is anything with CO2 or oxygen, like C25. It burns up the tungsten. If your supplier offers you one of those, they are thinking of MIG.

Why does my tungsten keep contaminating the weld?

Three common causes. First, you are dipping the tungsten into the puddle. Shorten your arc length or pull the torch back. Second, your amperage is too high for the tungsten diameter. Check the sizing chart above and step up a size. Third, you are touching the filler rod to the tungsten. Feed from the leading edge of the puddle, not the arc. If the tungsten is already contaminated (gray or balled tip), break off the end, regrind, and start fresh. A contaminated tungsten puts inclusions in your weld.

Other welding settings charts

MIG (GMAW) Settings Chart

Wire speed, voltage, and amps for steel, stainless, and aluminum.

Stick (SMAW) Settings Chart

Electrode amperage, polarity, and rod selection by application.

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