TIG welding amperage chart: a starting point by thickness
There is no universal TIG amperage: it changes with the machine, the joint, the position and the metal. What exists is a shop rule of thumb that gets you close on the first try. This page gives that rule, the chart that comes out of it and how to fine-tune by watching the puddle.
As a starting point on steel, use about 1 amp for every .001 in (0.025 mm) of thickness. That is 1/16 in (1.6 mm) ≈ 60 A, 1/8 in (3.2 mm) ≈ 125 A, 3/16 in (4.8 mm) ≈ 190 A. It is an estimate: confirm with your machine manual and, on qualified work, the WPS.
The rule: 1 amp per .001 in
The rule comes from how TIG amperage has long been thought of in inches: roughly 1 amp for each thousandth of an inch of thickness, on steel, on DCEN. Convert to metric and it is about 40 A per millimeter. It is a calculation to strike the arc near the right value, not a procedure value.
Estimated amps by thickness (steel, DCEN)
| Thickness | Calculation | Estimated current |
|---|---|---|
| 22 ga, .030 in (0.76 mm) | 30 thousandths | ≈ 30 A |
| 18 ga, .048 in (1.22 mm) | 48 thousandths | ≈ 50 A |
| 1/16 in (1.6 mm) | 62 thousandths | ≈ 60 A |
| 14 ga, .075 in (1.90 mm) | 75 thousandths | ≈ 75 A |
| 3/32 in (2.4 mm) | 94 thousandths | ≈ 95 A |
| 1/8 in (3.2 mm) | 125 thousandths | ≈ 125 A |
| 3/16 in (4.8 mm) | 188 thousandths | ≈ 190 A |
| 1/4 in (6.4 mm) | 250 thousandths | ≈ 250 A |
Estimate calculated from the shop rule of 1 A per .001 in (steel, DCEN, flat position). It is not an e-book table: it is a starting point to confirm with the machine manual and the WPS.
Joint design, position, root gap and machine type change the real current. On stainless and aluminum the rule is only a first reference. On qualified work the value that counts is the one in the WPS. If in doubt, start low and work up. Check the machine nameplate and duty cycle at 10-minute cycles before running high amps for long, and keep the circuit matched to the machine's input current.
The complete e-book
Reference tables, stick, MIG/MAG and TIG technique and safety in one PDF, written in plain American English.
Tungsten, current and gas by metal
Amperage is only half the setup. The other half is current type, tip shape and gas, which come straight from chapter 5 of the e-book:
| Metal | Current | Tip | Tungsten | Gas |
|---|---|---|---|---|
| Mild steel | DCEN | Pointed (2 to 3.5 times the diameter) | Orange (ceria), blue or gold (lanthana), or red (thoria) | Pure argon |
| Stainless | DCEN | Pointed | Orange, blue, gold or red | Pure argon; purge on tube |
| Aluminum | AC | Balled (up to 1.5 times the diameter) | Green (pure), brown (zirconia), orange or blue | Pure argon; argon/helium on thick parts |
Table 5.1 and section 5.3 of the e-book The Welder's Forge.
Tungsten diameter follows current: thin for low amps, thicker as amps climb. As a general guide on DCEN, .040 in (1.0 mm) covers roughly 15–80 A, 1/16 in (1.6 mm) about 70–150 A, 3/32 in (2.4 mm) about 150–250 A and 1/8 in (3.2 mm) above that. Confirm with the tungsten maker's chart. Colors, grinding and contamination are in tungsten electrode colors. Typical argon flow is 15–20 CFH (7–9 L/min).
How to fine-tune
- Set the machine from the chart and run a test bead on a scrap of the same metal, in the same position.
- Puddle is slow to form and the bead is tall and narrow: not enough current.
- Puddle grows fast, the edge sags or the metal burns through: too much current. Back off the pedal or lower the amps.
- Change in small steps and write down the value that worked for that thickness.
With a pedal, a common practice is to set the machine maximum a little above the estimate and control actual current with your foot. On aluminum it is nearly essential, because the part heats up fast; see how to weld aluminum.
Fixed references that do not depend on thickness
- Torch angle: 75–80° from the work.
- Tungsten distance: about the electrode diameter, 1/16–1/8 in (1.6–3.2 mm).
- Filler rod: 10–20°, at the leading edge of the puddle.
- Lens shade: shade 9–11 for TIG at 15–80 A (Table 2.1 of the e-book). Above 80 A, use a darker shade as the helmet maker and ANSI Z49.1 advise.
- Post-flow: enough to protect the end of the bead and the tungsten.
The full technique, with first exercises, is in TIG welding for beginners. If your machine is a MIG, the equivalent starting points are in the MIG welding settings chart.
Frequently asked questions
How many amps do I need to TIG weld 1/16 in steel?
Does the 1 amp per .001 in rule work for aluminum?
Where do I find the official amperage for my job?
Does tungsten diameter change with amperage?
Want all of this in one PDF?
The e-book The Welder's Forge covers stick, MIG/MAG and TIG from the first arc to the shop floor, with reference tables and technical figures, in plain American English.
PDF for phone, tablet or computer · instant access · 14-day guarantee