Table: welding current, electrode diameter and plate thickness
One table for stick welding: from the thickness of the part to the electrode diameter and the current range in every position. Figures are for rutile electrodes on low-carbon steel.
Short answer
Flat position: 2.0 mm — 50–80 A, 2.5 mm — 70–100 A, 3.0 mm — 80–130 A, 3.2 mm — 90–140 A, 4.0 mm — 130–190 A. The current calculator adds the correction for position and coating and checks the diameter against the thickness.
Welding current table by electrode diameter and position
| Thickness, mm | Electrode, mm | Flat, A | Horizontal, A | Vertical, A | Overhead, A |
|---|---|---|---|---|---|
| 1–2 | 1.6 | 40–60 | 35–55 | 35–50 | 30–50 |
| 1.5–3 | 2.0 | 50–80 | 45–70 | 45–70 | 40–65 |
| 2–4 | 2.5 | 70–100 | 65–90 | 60–85 | 55–80 |
| 3–5 | 3.0 | 80–130 | 70–115 | 70–110 | 65–105 |
| 3–6 | 3.2 | 90–140 | 80–125 | 75–120 | 70–110 |
| 6–12 | 4.0 | 130–190 | 115–170 | 110–160 | 105–150 |
| 10–20 | 5.0 | 180–250 | 160–225 | — | — |
| from 16 | 6.0 | 230–320 | 205–290 | — | — |
Electrodes of 5 and 6 mm are effectively never used vertically or overhead: the pool becomes too large to hold. In those positions the electrode goes no thicker than 4 mm and the joint is filled with several runs (technique in overhead welding).
Correction for the coating
| Coating | Typical brands | Factor | Current |
|---|---|---|---|
| Rutile | OK 46.00, ER 146 | 1.00 | AC / DC± |
| Basic | OK 48.00, EB 150 | 1.05 | DC+ |
| Cellulosic | OK 22.45 | 0.95 | DC+ / AC |
| Acid | — | 1.00 | AC / DC |
Electrode card: current, pieces per kilo and shade by diameter
One line per rod size, for setting up at the machine. The “Wall sheet” button above prints only the tables, large enough to read from the bench.
| Ø, mm | Thickness, mm | Flat, A | Vertical, A | Overhead, A | Length, mm | pcs/kg | Shade DIN (MMA) |
|---|---|---|---|---|---|---|---|
| 2.0 | 1.5–3 | 50–80 | 45–70 | 40–65 | 300 | 80 | 10 |
| 2.5 | 2–4 | 70–100 | 60–85 | 55–80 | 350 | 44 | 10–11 |
| 3.0 | 3–5 | 80–130 | 70–110 | 65–105 | 350 | 30 | 10–11 |
| 3.2 | 3–6 | 90–140 | 75–120 | 70–110 | 350 | 27 | 11 |
| 4.0 | 6–12 | 130–190 | 110–160 | 105–150 | 450 | 13 | 11–12 |
| 5.0 | 10–20 | 180–250 | — | — | 450 | 8 | 12 |
Baking depends on the coating, not the diameter: rutile 70–120 °C (1–2 h), basic 300–350 °C (2 h), cellulosic rods are not baked. If the packet of your brand says otherwise, follow the packet.
Electrode diameter and metal thickness
The same table read the other way: from the thickness of the part to the rod size. Where two or three sizes fit, the thinner one goes to vertical, overhead and gapped joints, the thicker one to the flat position.
| Metal thickness, mm | Electrode, mm | Flat-position current, A |
|---|---|---|
| 1 | 1.6 | 40–60 |
| 1.5 | 1.6 / 2.0 | 40–60 / 50–80 |
| 2 | 1.6 / 2.0 / 2.5 | 40–60 / 50–80 / 70–100 |
| 3 | 2.0 / 2.5 / 3.0 / 3.2 | 50–80 / 70–100 / 80–130 / 90–140 |
| 4 | 2.5 / 3.0 / 3.2 | 70–100 / 80–130 / 90–140 |
| 5 | 3.0 / 3.2 | 80–130 / 90–140 |
| 6 | 3.2 / 4.0 | 90–140 / 130–190 |
| 10 | 4.0 / 5.0 | 130–190 / 180–250 |
| 12 | 4.0 / 5.0 | 130–190 / 180–250 |
| 16 | 5.0 / 6.0 | 180–250 / 230–320 |
| 20 | 5.0 / 6.0 | 180–250 / 230–320 |
How many electrodes in a kilogram
| Diameter, mm | pcs/kg at 300 mm | pcs/kg at 350 mm | pcs/kg at 450 mm |
|---|---|---|---|
| 2.0 | 80 | 68 | 53 |
| 2.5 | 51 | 44 | 34 |
| 3.0 | 35 | 30 | 24 |
| 3.2 | 31 | 27 | 21 |
| 4.0 | 20 | 17 | 13 |
| 5.0 | 13 | 11 | 8 |
Worked out from the mass of a coated rod, with the same formula the electrode consumption calculator uses to turn kilograms into pieces. A 5 kg packet of 3.2 × 350 mm rods holds about 133.
Current wrong: what you see and what to change
Start in the middle of the range, run a bead on scrap and read it against the table.
| Symptom | Cause | What to do |
|---|---|---|
| The electrode sticks, the arc goes out | Current too low | Add 10–15 A |
| Narrow, high bead with no penetration | Current too low | Add current or slow the travel |
| Heavy spatter, the electrode glows red | Current too high | Take off 10–20 A, use a thinner electrode |
| Burn-through, undercut along the edges | Current too high | Drop the current, dwell less on the edge |
| The pool runs in the vertical | Current too high for the position | Cut it by 15 % against the flat position |
Work it out for your case
The table gives a range; the current calculator applies the corrections for position and coating straight away and checks whether the diameter suits your thickness.
Reading the table: three examples
The order never changes: material thickness → electrode diameter → position column → coating correction. Where you sit inside the range depends on the details — the gap, the number of runs, how hot the part already is.
- 5 mm plate, flat, rutile. The thickness falls in the 3–6 mm row — a 3.2 mm rod at 90–140 A. Start in the middle, about 115 A.
- 4 mm angle, vertical weld. Thin material on a vertical takes a thinner rod: 2.5 mm, “Vertical” column — 60–85 A. A 3.2 will do it too, but the pool is harder to hold.
- 10 mm beam, basic rod. The 6–12 mm row — a 4 mm rod, 130–190 A in the flat; the 1.05 correction for a basic coating gives 135–200 A. An overhead weld on the same beam — 4 mm at 110–160 A (coating correction already applied), or a 3.2 in several runs.
When the thickness falls between rows
The rows overlap on purpose: one thickness can be welded properly with two diameters. Position and gap decide.
- 3 mm is 2.5 (2–4 mm), 3.0 and 3.2 at once. Flat with no gap — a 3 mm rod, quicker and smoother. Vertical, overhead or a noticeable gap — 2.5: a smaller pool and less risk of burning through.
- 6 mm is the border between 3.2 and 4.0. A flat fillet goes in with a 4 mm rod in one run; a vertical is calmer with a 3.2.
- 10–12 mm is 4.0 and 5.0 territory. A 5 mm rod is used only flat and horizontal; the root goes in with a thinner rod anyway and the fill with the thick one.
Bottom or top of the range
The range in the table is wide — 50–60 A for 3–4 mm rods — and the weld behaves differently across it.
- Towards the bottom: root run, a wider gap than usual, a thin edge, a part already hot from earlier runs.
- Towards the top: fill runs, a fillet on thick plate in the flat, a cold heavy part that pulls the heat away.
- How to correct: the rod sticks and the bead is narrow — add 10–15 A; lots of spatter and undercut — take off 10–20 A. The full symptom table is on the current calculator page.
The amps-per-millimetre rule and why the table is better
The quick estimate I ≈ (30…40) · d works well in the middle of the
series: for 3.2 mm it gives 96–128 A, inside the table's 90–140 A. At the
ends it goes wrong: for a 4 mm rod it gives 120–160 A while the table goes
up to 190 A, and for 1.6 mm its upper figure, 64 A, is outside the table's
40–60 A. The rule is for a guess at the machine; the table is for setting up.
Applying the coating correction
The factor multiplies both ends of the range. A 3.2 mm rod in the flat: rutile 90–140 A, basic (×1.05) 95–145 A, cellulosic (×0.95) 85–135 A. The difference is small; the type of current matters more: basic rods as a rule want DC with the electrode positive (some grades also run on AC), rutile rods run happily on AC as well. If the packet gives a different current from the table, the maker is right.
Frequently asked questions
How do I estimate the current without the table?
Around 3 mm the rule of "30 to 40 amperes per millimetre of diameter" works: a 3.2 mm rod comes out at 96–128 A, inside the table’s 90–140 A. Thin rods sit lower than the rule (1.6 mm: 40–60 A), and from 4 mm up the table runs higher — a 4 mm rod goes up to 190 A.
Is the electrode diameter chosen for the thickness or for the current?
For the thickness — that comes first. The diameter decides how much metal you can lay in one run; the current merely serves the diameter you picked. If the current will not fit inside the range, the electrode is the wrong one.
What current for a 3.2 mm (1/8") rod on a vertical?
A rutile rod: 75–120 A; a basic rod: 80–125 A. That is 15 % below the flat position — on a vertical the pool has to stay small or it runs. Start in the middle of the range and adjust by the bead.
What amperage for a 4 mm (5/32") rod?
Rutile in the flat: 130–190 A; horizontal: 115–170 A; vertical: 110–160 A; overhead: 105–150 A. A basic 4 mm rod in the flat: 135–200 A. It suits material from 6 to 12 mm thick.
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