Welding cost estimating, from weld size to welder hours
Welding cost is weld metal, electrode, and the time it takes to put it down. Enter the fillet size and length, the process, deposition rate and operating factor. The calculator shows weld metal per foot, electrode to buy, arc hours and welder hours.
- Weld metal per foot
- Deposition efficiency by process
- Operating factor
- Cost per foot of weld
1 · Weld
2 · Process
3 · Cost
Steel density 0.2836 lb/in³ (490 lb/ft³). Fillet cross-section assumes an equal-leg flat fillet (leg² ÷ 2). Process efficiencies are rough editable defaults; use the electrode manufacturer's deposition data and your shop's measured operating factor.
Live formula
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Copy these results, then add your approved sample files in the trial brief.
Size drives volume fast
For an equal-leg fillet weld, the cross-section is a right triangle with area leg² ÷ 2. Weld metal per foot is that area × 12 in × steel density (0.2836 lb/in³), plus an allowance for convexity. Because area goes with the square of the leg, a 5/16 in fillet has about 56% more metal than a 1/4 in fillet, and a 3/8 in fillet more than twice as much. That is why weld sizes on details deserve as much attention as lengths.
- Leg size. From the weld symbol on the detail. Use the specified size, not the minimum for the plate.
- Length. Weld length per connection × number of connections. Intermittent welds count only the welded segments.
- Convexity / overweld. Real welds are rarely flat. An editable percentage covers it.
- Multi-pass and groove welds. Use the actual cross-sectional area from the joint detail; the fillet formula does not apply.
From joint to hours
| Fillet leg | Weld metal per ft (flat, lb) |
|---|---|
| 3/16 in | 0.060 |
| 1/4 in | 0.106 |
| 5/16 in | 0.166 |
| 3/8 in | 0.239 |
| 1/2 in | 0.425 |
Computed from leg² ÷ 2 × 12 × 0.2836 with no convexity. Process efficiencies in the calculator (SMAW 60%, FCAW 85%, GMAW 95%) are rough editable defaults; use your electrode manufacturer's data.
The number that changes the bid
Operating factor is the share of a welder's paid time with the arc lit. Fitting, tacking, positioning, chipping, grinding, moving the work and changing consumables take the rest. Shop welding on positioned work runs a higher operating factor than field welding overhead on an erected frame. A small change in this one input changes the hours more than any other, so set it from your own time studies or job history and keep separate values for shop and field.
The input most estimators struggle to get quickly is how many connections of each type are on the job. RenderDraw's AI takeoff proposes members and connection details from the drawings with their sheets, so the weld estimate is built on counts you can verify.
Member counts off the drawings, with the sheet attached.
RenderDraw's AI takeoff proposes steel member counts and lengths from plans, framing plans and schedules, links every row to its source, and sends low-confidence items to your estimator before the handoff to pricing.
- Counts and lengths by member. Proposed from the drawings and kept tied to the framing plan or schedule they came from.
- Uncertain items flagged. Items the AI can't confirm go to review instead of being guessed.
- Addenda through the same review. Send the changed sheets through takeoff and review, then reprice the members that changed.
- Your estimator decides. Connections, erection, coatings, risk and margin stay your call.
Test it on a real steel package
Send one structural set, ideally with an addendum. Sample files stay private while RenderDraw assesses the request. No obligation.
RenderDraw does not publish accuracy percentages or time-saved claims. Test it on your own plan set.
Questions estimators ask.
How do you estimate welding cost?
Compute weld metal from the joint size and length, convert to electrode with the deposition efficiency, convert weld metal to arc hours with the deposition rate, divide by the operating factor for welder hours, and price electrode, gas and labor.
How much weld metal is in a 1/4 inch fillet weld per foot?
About 0.106 lb per foot for a flat equal-leg fillet: 0.25² ÷ 2 × 12 × 0.2836.
What is a typical welding operating factor?
It varies widely between shops, processes and field versus shop work. Use your own measured values; the calculator default of 30% is an editable placeholder.
Does this work for groove welds?
Not with the fillet formula. Calculate the groove cross-section from the joint detail and enter an equivalent leg, or compute weld metal separately.
Can RenderDraw count welded connections?
RenderDraw's AI takeoff proposes members and connection-related quantities from drawings with sources and flags. Request a free sample takeoff.
Connection counts are where welding hours come from.
Send a steel package. RenderDraw proposes members and connection types from plans and details with their source, so weld estimates start from counts you have checked.
- Upload the plans, specs and schedules, plus an addendum if you have one.
- RenderDraw reviews the set and the scope you want tested.
- We follow up with extracted quantities, flagged items and next steps.