Welding shade number calculator
Which shade to set on the helmet, by process and current, to EN 169 and EN 379.
Too dark is a real problem too
A shade darker than necessary is not the safe option. It hides the edges of the pool, so the welder leans in to see, which puts the head into the fume plume and worsens the arc position at the same time. The right shade is the lightest one at which the arc is comfortable.
Shade number table to EN 169
| Current, A | MMA | MIG/MAG steel | MIG aluminium | TIG | Plasma | Gouging |
|---|---|---|---|---|---|---|
| up to 15 | 8 | — | — | 8 | 8 | — |
| 15–20 | 9 | — | — | 9 | 8 | — |
| 20–40 | 9 | — | — | 9 | 9 | — |
| 40–80 | 10 | 9 | — | 10 | 10 | — |
| 80–100 | 11 | 10 | 10 | 10 | 11 | — |
| 100–150 | 11 | 11 | 11 | 11 | 11 | 10 |
| 150–175 | 11 | 11 | 11 | 11 | 12 | 10 |
| 175–250 | 12 | 12 | 12 | 12 | 12 | 11 |
| 250–300 | 12 | 12 | 13 | 13 | 13 | 12 |
| 300–350 | 13 | 13 | 13 | 13 | 13 | 12 |
| 350–400 | 13 | 13 | 14 | 13 | 13 | 12 |
| 400–500 | 13 | 13 | 14 | 14 | 14 | 13 |
| over 500 | 14 | 14 | 15 | 14 | 14 | 13 |
What the shade actually blocks
Ultraviolet and infrared are filtered by the glass at every shade number — that part does not vary with the setting, and a compliant filter protects against arc eye even in its light state. The shade number controls visible light only. This matters when the auto-darkening cartridge fails to switch: the flash still burns the retina, but the UV protection was there regardless.
The four numbers stamped on an auto-darkening cartridge — optical class, diffusion, homogeneity and angle dependence — are explained on the welding helmet page. 1/1/1/1 is the best grade; the last digit is the one that matters most for long sessions.
Frequently asked questions
What happens with a shade that is too light?
The cornea takes too much ultraviolet, and hours later the eye feels full of sand — arc eye. It usually heals without lasting damage, but it is a burn, and it accumulates over the years.
And one that is too dark?
You stop seeing the pool and see only the arc. The weld suffers, and because you lean closer your head sits deeper in the fume plume. That is why the shade is matched to the current rather than set as dark as possible.
Is a fixed-shade helmet enough?
For occasional work in one process, yes. Anyone moving between 40 A TIG and 200 A MAG needs an adjustable shade — the difference is three to four steps, and fixed cartridges do not cover it.
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