Consumables, time and cost
Filler wire or electrode needed from deposited weld metal
- where
- filler to buy (kg)
- weld metal to deposit (kg)
- deposition efficiency (%)
- spools or packs
- spool or pack size (kg)
Explain this equation
Converts the weld metal you need into the weight of wire or electrodes to buy, and the number of spools or packs.
Not all of the filler ends up in the joint: some is lost as spatter, slag, fume or (for electrodes) stub ends. The deposition efficiency η is the percentage that does end up in the weld, so the filler needed is the deposit divided by that fraction. Dividing by the pack size and rounding up gives packs.
Quantity bought equals quantity needed divided by efficiency.
Sense check: 10 kg of deposit with solid MIG wire at 95% needs about 10.5 kg; with MMA electrodes at 65% it needs about 15.4 kg.
Watch out: efficiency depends on the process and how it is run. Long electrode stubs or high spatter can cut it well below the typical figures.
Turns the weld metal you need into the amount of wire or rods to buy, allowing for spatter, slag and stub-end losses.
Enter your values to see the result.
Good to know
Deposition efficiency is the share of filler that ends up in the weld. Published typical values: solid and metal-cored MIG wire 92–98 % (depends on gas and transfer mode), flux-cored about 87 %, submerged arc about 99 %, and MMA about 65 % because of slag, spatter and stub ends. Get the weld metal mass from the fillet or butt weld calculators.
Common mistake
Ordering MMA rods by weld metal weight. Roughly a third of each rod ends up as stub, slag and spatter.
Limits
Typical efficiencies only; long stubs, high spatter settings or CO₂ shielding lower them. Use the manufacturer’s data where given.
Sources
- The Fabricator (The Welder): Understanding the relationship between deposition rate, deposition efficiency and production output (SMAW about 65 %, GMAW solid and metal-cored 92–98 %, FCAW about 87 %, SAW about 99 %)
- Determining the cost of welding (reprint): L&O per kg = rate ÷ (deposition rate × operating factor); filler per kg = price ÷ electrode efficiency; gas = flow × price ÷ deposition rate
Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow the welding procedure specification (WPS), BS EN ISO 15614/9606, BS EN 1090, BS EN 1993 and manufacturers’ data. Structural welds need qualified welders and engineered designs.