Electrode Consumption Calculator
The calculator models an equal-leg fillet weld as a right-angled triangle, so its cross-sectional area is leg²/2.
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the fillet leg size in mm and the total length of weld to be deposited in metres.
- Optionally set the deposition (transfer) efficiency — leave blank for the SMAW default of 65%, or enter ~90–98% for MIG/MAG.
- Optionally enter the usable weld metal deposited per stick electrode (grams) to get an approximate electrode count to buy.
How it works
The calculator models an equal-leg fillet weld as a right-angled triangle, so its cross-sectional area is leg²/2. Multiplying that area by the total weld length gives the volume of deposited weld metal, and multiplying by the steel density of 7,850 kg/m³ converts that volume to the mass of weld metal that ends up in the joint.
Not all the consumable becomes weld metal — some is lost as spatter, slag, stub ends and fume. Deposition (transfer) efficiency captures this: the filler mass you must actually purchase and melt is the deposited mass divided by the efficiency fraction (≈60–65% for SMAW stick, ≈90–98% for solid-wire MIG/MAG). If you supply the usable weld metal per electrode, dividing the deposited mass by that rod capacity and rounding up estimates how many electrodes to order.
Worked example
6 mm fillet over 10 m with 65% SMAW efficiency. For a 6 mm equal-leg fillet weld running a total of 10 m, the cross-section area is 6²/2 = 18 mm². Over 10 m (10,000 mm) that is a weld metal volume of 180 cm³, which at a steel density of 7,850 kg/m³ weighs 1.413 kg of deposited metal. At a typical SMAW deposition efficiency of 65%, you must actually melt 1.413 ÷ 0.65 = 2.174 kg of filler. If each electrode deposits about 25 g of usable weld metal, you need ceil(1,413 g ÷ 25 g) = 57 electrodes.
Common mistakes
- Entering the weld length in millimetres instead of metres — the length field expects metres, so 10 m not 10,000.
- Confusing deposited weld metal with filler purchased: the deposited mass is what stays in the joint, while the filler required (deposited ÷ efficiency) is the larger figure you actually buy.
- Using an SMAW efficiency (~65%) for a MIG/MAG job (~90–98%), which overstates consumable purchase by 30–50%.
Frequently asked questions
What deposition efficiency should I use?
As a rough guide, SMAW (stick) is about 60–65% because of stub-end and slag losses, flux-cored is around 80–85%, and solid-wire MIG/MAG is about 90–98%. Always prefer the figure on your consumable's data sheet — this tool defaults to 65% (SMAW) when you leave the field blank.
Does this include root gaps, reinforcement or multi-pass build-up?
No. It models a single equal-leg fillet triangle (area = leg²/2). Real welds often have a convex face, root penetration or extra passes, so actual consumption is usually a bit higher. Add a contingency (commonly 10–20%) for procurement and treat the result as a planning estimate only.
Can I use it for carbon steel and stainless?
The mass uses a steel density of 7,850 kg/m³, which is accurate for carbon and low-alloy steel and close enough for most stainless grades (≈7,900–8,000 kg/m³). For very different filler densities, scale the mass result by your material's density ÷ 7,850.
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