Welding Calculator
Free Welding Calculator for materials specifications projects. Enter dimensions to get material lists and cost estimates.
Reviewed by Abdullah, Technical Content Specialist
Formula
Filler Metal = (Cross-Section x Length x Density) / Deposition Efficiency
Determine the weld joint cross-sectional area based on geometry (fillet: 0.5 x leg x leg, V-groove: t x t x tan(half-angle)). Multiply by weld length for volume. Convert to mass using metal density (7.85 g/cm3 for steel). Divide by deposition efficiency to account for process losses like spatter, slag, and stub ends.
Worked Examples
Example 1: 6mm Fillet Weld on Steel Beam
Problem:Calculate filler metal for a 6mm fillet weld, 2 meters long, using E7018 electrodes.
Solution:Cross-section = 0.5 x 6 x 6 = 18 mm2\nVolume = 0.18 cm2 x 200 cm = 36 cm3\nWeld metal = 36 x 7.85 / 1000 = 0.283 kg\nFiller needed = 0.283 / 0.65 = 0.435 kg\nElectrodes (350mm) = 0.435 / 0.045 = 10 rods
Result:0.435 kg E7018 needed (about 10 electrodes), 1 pass
Example 2: V-Groove Butt Weld
Problem:Calculate filler for a 60-degree V-groove butt weld on 12mm plate, 500mm long, using ER70S-6 MIG wire.
Solution:Cross-section = 12 x 12 x tan(30) = 83.1 mm2\nVolume = 0.831 cm2 x 50 cm = 41.6 cm3\nWeld metal = 41.6 x 7.85 / 1000 = 0.326 kg\nFiller = 0.326 / 0.95 = 0.343 kg MIG wire
Result:0.343 kg ER70S-6 wire needed, approximately 4 passes
Frequently Asked Questions
How do I calculate the amount of welding filler metal needed?
Calculate the weld cross-sectional area based on the joint type and dimensions, then multiply by the weld length to get the volume of weld metal. Multiply the volume by the density of the filler metal (typically 7.85 g/cm3 for steel) to get the net weld deposit weight. Then divide by the deposition efficiency of the welding process: SMAW (stick) is typically 60-65%, MIG/GMAW is 90-95%, and flux-cored is 80-85%. The result is the total filler metal weight you need to purchase.
What is deposition efficiency in welding?
Deposition efficiency is the ratio of weld metal deposited to the total weight of filler metal consumed, expressed as a percentage. SMAW (stick) welding has 55-65% efficiency because the coating flux, stub loss, and spatter consume material. GMAW (MIG) achieves 90-97% efficiency since there is minimal spatter and no stub loss. FCAW (flux-core) falls between at 80-90%. Higher deposition efficiency means less filler metal purchased per kilogram of weld deposit, directly reducing material costs on large projects.
References
Reviewed by Abdullah, Technical Content Specialist · Editorial policy