Weld Deposition Rate Calculator

The Formula

Deposition rate — the pounds of filler metal deposited per hour of arc time — is the single metric that separates a profitable welding job from one that bleeds money. Higher deposition means faster completion, less labour cost, and lower gas consumption per weld inch. The table below compares the three most common arc welding processes at standard flat-position parameters.

| Process | Wire/Rod | Deposition Rate (lbs/hr) | Efficiency | Best For | |---|---|---|---|---| | GMAW 0.035" | ER70S-6 | 4.5 | 95% | Production fabrication, thin-to-medium plate | | GMAW 0.045" | ER70S-6 | 8.0 | 95% | Heavy structural plate, high-volume fab | | SMAW 1/8" 7018 | E7018 | 3.5 | 65% | Field structural, pipeline, all-position | | SMAW 3/32" 6013 | E6013 | 2.5 | 65% | Maintenance, thin material, general purpose | | FCAW 0.045" | E71T-1 | 9.0 | 87% | Outdoor structural, heavy plate, windy conditions |

Rates assume flat position and manufacturer-recommended parameters. Overhead position reduces these figures by 30-40% because of smaller puddle size and slower travel speed. Vertical-up position drops rates 20-30%.

Why Deposition Efficiency Shapes Your Material Order

Welding presents serious safety hazards including arc flash (UV radiation), toxic fumes, fire, and electric shock. Always wear proper PPE: auto-darkening helmet (shade 10+ for MIG/stick, shade 8+ for TIG), FR leather gloves, FR jacket or apron, steel-toed boots. Work in ventilated areas or use fume extraction. Keep a fire extinguisher within 10 feet.

The gap between deposited metal and purchased metal is where material budgets go wrong. Deposition efficiency tells you what percentage of the filler you buy actually ends up in the weld joint — the rest becomes waste in different forms depending on the process.

GMAW runs at 95% efficiency because the wire feeds continuously with minimal spatter. For every 10 lbs of wire you put on the spool, 9.5 lbs end up in the joint. The only losses are minor spatter and the short wire trim at the end of each spool. This makes GMAW material ordering straightforward: calculate the deposited weight and add 5-8% for waste and spool ends.

SMAW drops to 65% efficiency because of three compounding waste sources. First, each electrode has a 2-3 inch stub that gets discarded — the welder cannot burn the rod down to zero. Second, the flux coating (roughly 30% of the rod by weight) burns off as shielding gas and slag, contributing zero deposited metal. Third, spatter losses run higher than GMAW because of the less stable arc. The result: you purchase 54% more rod than you deposit. For a job needing 100 lbs of deposited metal, order 154 lbs of electrodes.

FCAW sits between the two at 87% efficiency. The flux core adds weight that burns off as slag, but the continuous wire feed eliminates stub loss. FCAW spatter rates are moderate — higher than GMAW, lower than SMAW. For accurate filler ordering on any process, use the [weld time calculator](/calculators/materials/weld-time-calculator) alongside this tool to get both the material quantity and the labour hours for your quote.

GMAW vs. SMAW vs. FCAW: Picking the Right Process for Efficiency

Each process trades off efficiency, portability, and weld quality differently. The right choice depends on where you are welding, what position the joints are in, and whether speed or flexibility matters more.

**GMAW (MIG)** delivers the highest deposition efficiency and fastest rates in a shop setting. The continuous wire feed means zero time lost to electrode changes, and the 95% efficiency keeps material waste minimal. The limitation is environmental: GMAW requires shielding gas (typically 75/25 argon/CO2) that disperses in wind above 5-8 mph. It also needs a wire feeder and gas cylinder, which limits portability. For indoor fabrication where throughput drives profitability, GMAW is the default choice.

**SMAW (stick)** sacrifices efficiency for versatility. At 65% deposition efficiency, stick welding wastes more filler per joint than any other common process. But it works everywhere — outdoors in wind and rain, in confined spaces, at height, in remote locations with only a portable welder and a box of rods. No gas cylinder, no wire feeder, no wind screens. For field structural work, pipeline welding, and maintenance repairs where getting to the joint matters more than deposition speed, stick remains dominant.

**FCAW (flux-core)** bridges the gap. Self-shielded FCAW needs no external gas, making it wind-tolerant like stick, while the continuous wire feed pushes deposition rates to 9+ lbs/hr — the highest of any semi-automatic process on heavy plate. The 87% efficiency beats stick by a wide margin. The trade-off is more spatter and slag removal compared to GMAW, and the wire costs more per pound. For outdoor structural steel, shipyard work, and heavy fabrication where wind makes GMAW impractical but stick is too slow, FCAW is the production answer.

Real-World Scenarios

Estimating filler metal for a project follows a consistent sequence regardless of process. These steps produce a purchase quantity, not just a deposited weight — the distinction matters for material ordering.

1. **Calculate weld cross-section from joint dimensions.** For fillet welds, the cross-section is a triangle: 0.5 x leg x leg. A 1/4-inch fillet has a cross-section of 0.5 x 0.25 x 0.25 = 0.03125 square inches. For groove welds, the cross-section depends on the bevel angle and root opening — consult the WPS (Welding Procedure Specification) for the joint geometry.

2. **Multiply by total weld length and number of passes.** Sum every weld on the project drawing. A fabricated beam with two flange-to-web fillet welds along a 20-foot beam has 2 x 240 = 480 inches of weld. Multiply the cross-section by this total length and by the number of passes per weld.

3. **Convert volume to weight using steel density.** Multiply the volume in cubic inches by 0.283 lbs/cu in for carbon steel, or 0.289 lbs/cu in for stainless steel. This gives the deposited filler weight — the metal that actually ends up in the joint.

4. **Divide by deposition efficiency for purchase weight.** This is the step most estimators skip, and it is why material orders come up short. Divide deposited weight by 0.95 for GMAW, 0.87 for FCAW, or 0.65 for SMAW to get the weight you need to order.

5. **Add 10-15% for waste, practice starts, and rejects.** Even with accurate cross-section calculations, real-world factors inflate consumption: practice welds on scrap, rejected welds that get ground out and re-welded, arc strikes, and wire or rod damaged in handling. For the time dimension of your welding estimate, the [weld time calculator](/calculators/materials/weld-time-calculator) converts deposition rate into hours on the project.

What to Watch For

**What does MIG wire cost per pound?**

ER70S-6 carbon steel MIG wire runs $1.80-$3.50 per pound as of March 2026, US national averages. The price depends heavily on spool size: 2-lb spools cost $3.00-$3.50/lb while 44-lb drums drop to $1.80-$2.20/lb. For production shops burning through multiple spools per week, buying in drums cuts wire cost by 30-40%. Specialty wires (stainless ER308L, aluminium ER4043) cost $8-$20/lb regardless of spool size.

**What about 7018 stick rod pricing?**

E7018 electrodes run $2.80-$4.00 per pound in 10-lb or 50-lb boxes as of March 2026, US averages. Low-hydrogen rods like 7018 must be stored in rod ovens (250-300 degrees F) to prevent moisture absorption — exposed rods cause porosity and hydrogen cracking in the weld. This storage requirement adds equipment cost that many estimators overlook. E6013 general-purpose rods are cheaper at $2.00-$3.00/lb and do not require oven storage.

**How does flux-core wire pricing compare?**

E71T-1 flux-cored wire runs $2.20-$3.50 per pound in 33-lb spools, March 2026 US averages. Self-shielded FCAW wire (E71T-8, E71T-11) costs slightly more at $2.50-$4.00/lb because of the more complex flux formulation. For structural steel projects where weld sizing ties to beam design, the [steel beam size calculator](/calculators/structural/steel-beam-size-calculator) handles the structural engineering side of the estimate.

Worked Examples