Workshop and Metalwork Calculators
Welding wire usage.
Choose the joint (fillet or single-V groove) and the process, then enter the weld size and total length. You get the weld metal in kg and lb and the wire or electrode to buy after deposition losses. Runs in your browser; nothing is sent or stored.
Inputs
Result
Fill the form and press Calculate.
Answer first. Consumable = weld metal weight / deposition efficiency. Weld metal weight = section area x length x 7.85 g/cm3 for steel. A 6 mm fillet over 1 m is 0.141 kg of weld metal, or 0.149 kg of MIG wire at 95 percent.
Worked example
A 6 mm equal-leg fillet, 1 m long, MIG welded with solid wire. Section area = 6 x 6 / 2 = 18 mm2. Weld metal = 18 mm2 x 1 m x 7.85 g/cm3 = 0.141 kg. At 95% deposition efficiency the wire needed is 0.141 / 0.95 = 0.149 kg (about 0.33 lb). With stick electrodes at 55% the same weld takes 0.257 kg.
How it works
Formula. The Kobe Steel guide gives C = (A1 + A2) x L x G / E x 1/10, where C is the consumable in kg, A1 the weld metal section and A2 the reinforcement section in mm2, L the weld length in metres, G = 7.85 g/cm3 for the weld metal and E the deposition efficiency in percent. The same value is shown here as weld metal weight divided by efficiency.
Efficiencies used. Stick (SMAW) covered electrodes 55 percent, MIG (GMAW) solid or metal-cored wire 95 percent, flux-cored (FCAW) wire 90 percent, submerged arc (SAW) solid wire 100 percent. The source gives these for welding ferritic steel; do not use this tool for aluminum or stainless weld metal, whose density differs.
Joint sections. An equal-leg fillet has a triangular section of leg x leg / 2. A single-V groove is estimated as thickness x thickness x tan(half the groove angle) plus root opening x thickness; a root face or a different groove shape changes it. For other shapes, work out the section area yourself and enter it directly. Add the weld face reinforcement as area A2 if you want it counted.
Real waste. The efficiency is a single average figure for the process. Wire cut off or left on the spool, test welds and an oversized bead are not counted, so buy a margin on top.
Safety. Welding produces arc radiation, fumes, sparks and burns. Use a proper welding helmet, gloves and flame-resistant clothing, ventilate or extract fumes, and remove flammables from the area. This is a quantity estimate, not a welding procedure or professional advice.
Sources
- How to calculate welding consumption - The ABC's of Arc Welding, Kobe Steel (opened 2026-10-08)
The formula, the 7.85 g/cm3 weld metal figure and the deposition efficiencies are from the page above. 1 ft = 0.3048 m, 1 in = 25.4 mm and 1 lb = 0.45359237 kg.
FAQ
How much MIG wire do I need?
Work out the weld metal weight, then divide by 0.95 for solid or metal-cored wire. A 6 mm fillet over 10 m needs about 1.5 kg.
What is deposition efficiency?
The share of the consumable that ends up in the weld. The Kobe Steel guide lists 55 percent for covered electrodes, 95 percent for MIG solid wire, 90 percent for flux-cored wire and 100 percent for submerged arc wire.
Why does stick welding use more consumable?
Its deposition efficiency in the guide is only 55 percent, so about 1.8 kg of electrode is needed for each kg of weld metal.
Does this work for stainless or aluminum?
No. The guide's 7.85 g/cm3 figure is for ferritic steel weld metal.
Is a 1/4 in fillet the same as a 6 mm fillet?
Close: 1/4 in is 6.35 mm. Enter the leg size in the unit you choose and the tool converts it.