Welding and Metal Fab

How to Calculate Welding Cost per Part

Welding cost per part includes arc-on time, filler metal, shielding gas, power, labor, and overhead. Here is how to build the cost model and where estimates typically go wrong.

Welding cost per part equals arc-on time divided by 3600 multiplied by labor rate plus overhead rate plus power rate, then add wire consumption x wire price and gas consumption x gas price. For a MIG weld with 8 minutes of arc time at a combined labor and overhead rate of $65 per hour, labor and overhead cost is about $8.67. If wire use is 0.9 kg at $3.50 per kg and gas use is 18 liters at $0.008 per liter, those add $3.15 and $0.14. Total cost is about $11.96 per part before any post-weld grind, inspection, or repair. That is why even small reductions in arc time or filler use can move margin quickly on repeat fabrication work.

The key inputs are arc-on time, operator factor, filler consumption, shielding gas consumption, power use, and labor rate. Operator factor is the ratio of arc-on time to total labor time, and it is often only 20% to 40% in manual welding versus 70% to 90% in automated cells. Wire consumption equals deposition rate x arc-on time, while gas comes from flow rate x welding minutes. Material and consumable prices come from purchasing, and time values should come from time studies or production history, not from idealized WPS assumptions. On structural and heavy fab work, joint position and fit-up quality often affect total labor more than wire price does.

The most common mistake is estimating only arc time and ignoring non-arc labor such as fit-up, repositioning, chip removal, and inter-pass inspection. Another big miss is using wire consumed as if all of it becomes deposited weld metal. Deposition efficiency is typically 95% to 98% for solid MIG wire and about 80% to 85% for flux-core because spatter and loss are real. Shops also underestimate rework cost, even though repair time on an existing joint is often 3 to 5 times the original weld time. Joint design errors, poor access, and out-of-position welding can easily double the labor on paper-good quotes.

Use the result to compare weld processes, joint designs, and automation options. A joint that can be repositioned into flat welding may cut arc time and filler use dramatically compared with the same joint welded vertical or overhead. If operator factor is low, the best return may come from better fixturing or positioners rather than from tweaking amperage or travel speed. The cost model also helps estimators explain why a low wire-price supplier quote is not actually low cost if their labor assumption is unrealistic. Welding quotes get more accurate when the result is broken into labor, consumables, and rework risk.

Track repair rate, deposition efficiency, and actual arc-on percentage alongside part cost. If a specific joint type shows high repair rate, the real problem is often procedure design or training, not the welder alone. Related metrics such as weld deposition rate, fit-up time, and fabrication quote margin help show which lever matters most. Also review whether code requirements, NDT, and post-weld cleaning are included because they can outweigh gas and power cost on critical work. A welding cost model is only useful when it matches the shop's real mix of welding time and non-welding time.

Published 2026-05-28.