Welding cost for structural steel runs roughly $3 to $6 per linear foot for a single-pass 1/4 inch fillet in the shop, climbing to $12 to $20 per foot for a multipass 1/2 inch fillet. Labor is 80 to 85 percent of that cost, so weld size, position, and process — not wire price — drive the number.
Most estimators price welding indirectly, buried inside an hours-per-ton allowance. That works fine on repetitive bolted framing. It falls apart on moment frames, trusses, and built-up members, where welding is the single biggest labor line and a wrong assumption swings the bid by five figures. This guide covers how to price welds directly when the job demands it.
What drives welding cost on structural steel?
Four things, in order of impact:
- Weld size. Weld metal volume grows with the square of the fillet leg. A 1/2 inch fillet contains four times the metal of a 1/4 inch fillet — more on this below, because it's the trap that sinks bids.
- Position. Flat-position welding is the baseline. Horizontal adds 10 to 30 percent, vertical-up runs 1.5 to 2 times flat, and overhead runs 2 to 3 times. In the shop you rotate the piece into the flat position; in the field you weld it where it hangs.
- Process. Deposition rate — pounds of weld metal laid down per arc hour — varies enormously by process. Stick (SMAW) deposits 2 to 5 lbs/hr. Wire processes (GMAW/FCAW) run 5 to 12 lbs/hr. Submerged arc on a fitted girder can exceed 20 lbs/hr. Same weld, very different clock.
- Prep and fit-up. A fillet weld on a square-cut edge needs almost no prep. A complete-joint-penetration (CJP) groove weld needs beveling, backing bars or back-gouging, and often ultrasonic testing. CJP moment connections are why moment frames cost more per ton than braced frames — the steel is similar, the welding isn't.
How much does welding cost per linear foot?
Editorial ranges for shop welding at a $70 to $85 per hour loaded rate, standard structural quality, flat or horizontal position:
| Fillet size | Weld metal (lbs/ft) | Relative volume | Typical passes | Shop cost per foot |
|---|---|---|---|---|
| 3/16 in | 0.06 | 0.6x | 1 | $2 – $4 |
| 1/4 in | 0.11 | 1.0x | 1 | $3 – $6 |
| 5/16 in | 0.17 | 1.6x | 1 | $4 – $7 |
| 3/8 in | 0.24 | 2.3x | 2 – 3 | $7 – $12 |
| 1/2 in | 0.43 | 4.0x | 4 – 6 | $12 – $20 |
| 5/8 in | 0.66 | 6.3x | 6 – 9 | $18 – $30 |
Two patterns worth internalizing. First, 5/16 inch is the largest fillet most shops make in a single pass with wire processes — it's the sweet spot of the table, and it's why engineers who size welds economically stop there. Second, cost grows faster than volume once you go multipass, because every extra pass adds interpass cleaning, slag removal, and repositioning time that deposits zero metal.
CJP groove welds are a different animal: figure $25 to $60 per foot on 3/4 inch to 1 1/2 inch material in the shop once you count beveling, backing, and inspection — and more when UT reveals a repair.
Why does doubling the fillet size quadruple the cost?
Geometry. A fillet weld's cross-section is a right triangle with legs equal to the weld size. Area = leg squared, divided by 2. Double the leg and the area — and therefore the weld metal volume you must deposit — goes up four times:
- 1/4 in fillet: 0.031 sq in cross-section, about 0.11 lbs of steel per foot
- 1/2 in fillet: 0.125 sq in cross-section, about 0.43 lbs per foot
Same joint length, four times the metal, plus the multipass penalty on top. This is why a detailer or engineer who bumps every fillet "one size for safety" is quietly doubling your weld cost, and why overwelding — welders routinely run 1/16 inch over the callout — adds 20 to 40 percent to consumed metal without anyone noticing. When you do your takeoff, record the specified size and add a measured overwelding allowance rather than letting it hide in the hours.
How do you estimate weld cost from deposition rates?
The estimator's formula, simplified:
Cost per foot = (weld metal lbs/ft ÷ deposition rate ÷ operating factor) x loaded labor rate + consumables
The operating factor is the fraction of the shift the arc is actually on — the number nobody wants to say out loud. A good shop runs 30 to 50 percent; the rest is fitting, cleaning, repositioning, and grabbing the grinder. Field crews run 15 to 25 percent.
Worked example — 3/8 inch shop fillet, FCAW:
- Weld metal: 0.24 lbs/ft, plus 20 percent overwelding = 0.29 lbs/ft
- Deposition: 10 lbs/hr at 40 percent operating factor = 4 effective lbs/hr
- Time: 0.29 ÷ 4 = 0.073 hr/ft
- Labor: 0.073 x $80 = $5.80/ft, plus roughly $0.50/ft in wire, gas, and power
Call it $6.30 per foot — right in the table's range. Once you trust the formula, you can price any weld from three inputs: size, process, and where it's being made.
Why is field welding so much more expensive than shop welding?
Expect field welds to run 2 to 3 times the shop cost per foot, sometimes more. The reasons stack:
| Factor | Shop | Field |
|---|---|---|
| Operating factor | 30 – 50% | 15 – 25% |
| Position | Rotate to flat | Weld in place, often vertical/overhead |
| Process | FCAW/SAW, high deposition | Often SMAW or self-shielded FCAW |
| Environment | Controlled | Wind, rain, temperature, preheat in the open |
| Access | Piece at bench height | Ladders, lifts, tie-offs |
| Labor rate | Shop rate | Ironworker field rate, typically higher |
This is why erection-friendly design bolts everything it can and why a connection schedule full of field-welded moment connections should set off alarms at bid time. Our steel connection types guide covers which connections drive field welding, and the 2026 fabrication cost breakdown shows where welding sits inside total hours per ton. AISC's certification and specification resources at aisc.org are the reference point for the quality requirements — D1.1 compliance, welder qualification, inspection — that set the floor under all of these numbers.
What should you pull off the drawings for a welding estimate?
A weld takeoff is a length takeoff with attributes. For every welded joint, capture:
- Weld symbol and size — fillet vs groove, leg size, intermittent vs continuous. Intermittent welds (say, 3 inches at 12 inch centers) cut deposited length by 75 percent; missing the pitch means quadruple-counting.
- Length — from the member geometry, both sides where the symbol says so. A both-sides symbol doubles the footage.
- Position — shop or field (the flag on the symbol), and what position the field weld will actually be made in.
- NDE requirements — UT on CJP welds, magnet particle on others. Inspection can add $2 to $8 per foot on tested welds.
- Finish requirements — ground-flush welds on architecturally exposed steel can double the labor per foot again.
Counting members accurately is the prerequisite — you can't total weld footage for 40 beam-to-column joints if you counted 34 beams. SteelFlo finds every steel member label on every page of a PDF drawing set and draws a bounding box around each one for you to verify, so the count feeding your connection and weld quantities is the count actually on the drawings — with AI detection plus human verification running 95 to 99 percent accuracy. The member list exports straight to a bill of materials you can hang your joint counts on.
Quick answers
How much does welding cost per foot? Roughly $3 to $6 per foot for a shop 1/4 inch fillet, $7 to $12 for 3/8 inch, and $12 to $20 for 1/2 inch. Field welds run 2 to 3 times shop cost.
What percentage of weld cost is labor? Typically 80 to 85 percent. Consumables — wire, gas, electrodes — are usually under 15 percent, which is why weld size and position matter far more than filler metal price.
Why does a bigger fillet cost so much more? Weld volume grows with the square of the leg size. Doubling a fillet from 1/4 inch to 1/2 inch means four times the weld metal, plus extra passes.
What's a realistic operating factor? Arc-on time is 30 to 50 percent of paid time in a good shop and 15 to 25 percent in the field. Estimating at 100 percent arc time is the classic rookie error.
Before you can price the welds, you need an accurate member count to hang them on. Run your next drawing set through SteelFlo's takeoff — every member found, boxed, and verifiable — or sanity-check tonnage first with the free steel weight calculator.