How do I pick tungsten diameter from amperage?

Each electrode diameter carries a usable amperage band, and AC bands are lower than DC because the electrode heats on both halves of the cycle. The tool estimates amps from thickness, then picks the smallest diameter whose band covers that current.

Ceriated or lanthanated — which should I use?

Both are non-radioactive, start easily, and run well on AC and DC, so they are the best general-purpose choices today. Thoriated still welds high-amp DC steadily but is mildly radioactive, and pure tungsten is mainly for old transformer AC machines.

Why grind a point for DC but ball the tip for AC?

On DCEN the electrode stays relatively cool, so a sharp ground point concentrates the arc for a narrow bead. On AC the electrode gets much hotter and the tip naturally forms a ball, which is the stable shape for aluminum.

How is the amperage estimated?

It uses the common rule of roughly one amp per 0.025 mm of steel thickness, then scales up for aluminum, which needs more heat on AC, and slightly down for stainless. Treat it as a starting point and fine-tune on the machine.

Which way should I grind the tip?

Grind lengthwise so the grinding marks run along the electrode toward the tip, not around it. Circumferential marks cause the arc to wander; a lengthwise finish gives a stable, focused arc.

TIG Tungsten Size & Prep Calculator

The wrong tungsten makes a TIG arc wander, spit, or overheat the electrode. This tool picks the right diameter, alloy, and tip preparation for your material, thickness, and current type, and tells you the amperage band so the electrode is neither starved nor cooked.

How it works

Amperage is the anchor. The calculator estimates working current from thickness using the classic rule of about one amp per 0.025 mm of steel, scaling up for aluminum on AC and down slightly for stainless:

amps = (thickness_mm / 0.025) × material_factor

It then selects the smallest electrode diameter whose published amperage band covers that current. AC bands are lower than DC bands for the same diameter because alternating current heats the electrode on both polarity halves. Tip prep follows current type: DCEN gets a ground, lightly truncated point; AC gets a balled tip; and the alloy defaults to non-radioactive 2% ceriated or lanthanated, with thoriated offered for steady high-amp DC.

Example and tips

Welding 3 mm mild steel on DCEN gives roughly 120 A, which lands on a 3/32 in (2.4 mm) electrode ground to a fine truncated point. Switch to 3 mm aluminum on AC and the heat demand rises, pushing toward the same or the next diameter up with a balled tip. Always grind lengthwise, keep a dedicated wheel for tungsten, and back off the amperage if the tip starts to melt or the arc spits.