Welding Wire Consumption Calculator
Calculate the total weight of MIG/MAG welding wire needed for a job by entering the weld bead cross-section, total weld length, wire material density, and process deposition efficiency. The result accounts for spatter loss and tells you how many spools to purchase. Wire weight = (Weld cross-section area x Weld length x Wire density) / Deposition efficiency.
Welding wire consumption formula
Bead cross-section (m^2) = (Width/1000) x (Height/1000)
Weld volume (m^3) = Bead cross-section x Weld length (m)
Wire required (kg) = Weld volume x Wire density / (Deposition efficiency / 100)
Spools = ceil(Wire required / Spool size)
Bead cross-section is approximated as a rectangle. For more accurate estimates, use the actual cross-sectional geometry from the weld procedure specification (WPS) per AWS D1.1 or equivalent.
Deposition efficiency by process
- GMAW/MIG solid wire (short circuit): 85-90%
- GMAW/MIG solid wire (spray transfer): 92-98%
- FCAW flux-cored wire: 78-88%
- SMAW (stick): 60-75%
- GTAW/TIG (filler rod): 95-100%
Source: AWS Welding Handbook (9th Edition), Volume 2: Welding Processes.
Welding wire consumption: frequently asked questions
How is welding wire consumption calculated?
Wire consumption (kg) = Weld volume (m^3) x Wire density (kg/m^3) / Deposition efficiency. Weld volume = Cross-section area (m^2) x Weld length (m). The deposition efficiency accounts for wire spatter loss; for MIG welding it is typically 0.85-0.95 (85-95%).
What is deposition efficiency in welding?
Deposition efficiency is the fraction of wire consumed that actually becomes weld metal, expressed as a decimal. The rest is lost as spatter and smoke. MIG/MAG (GMAW) typically achieves 85-95% efficiency. FCAW (flux-cored) achieves 78-88%. SMAW (stick) achieves 60-75%. Higher efficiency means less wire waste.
How do I estimate the weld bead cross-section?
For a simple fillet weld, the cross-sectional area is approximately 0.5 x leg x leg (for an equal leg fillet of leg length 'a', area = 0.5 x a^2). For butt welds, the area depends on the joint preparation (V-groove, U-groove) and the included angle. Use the actual weld cross-section from the weld procedure specification (WPS) where available.
What is the density of MIG welding wire?
The density of carbon steel MIG wire (ER70S-6) is approximately 7,850 kg/m^3, the same as mild steel. Stainless steel wire (ER308L) is approximately 7,900 kg/m^3. Aluminum wire (ER4043) is approximately 2,680 kg/m^3. Densities are per AWS and ESAB filler metal specifications.
How many kilograms of wire are in a standard spool?
Common MIG wire spool sizes: 5 kg (11 lb), 15 kg (33 lb), and 200 kg (441 lb) drums. Wire diameter also affects the spool meterage. For a 0.8 mm ER70S-6 wire, a 5 kg spool contains approximately 700-750 meters of wire. This calculator gives you the total weight needed so you can determine the number of spools required.
Official sources
- American Welding Society (AWS): AWS Welding Standards and Handbook.
- AWS D1.1 Structural Welding Code: AWS D1.1 Structural Welding Code (Steel).
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.