Steel fabrication estimate

It builds a steel fabrication estimate (stairs, mezzanines, canopies, railings, light structures) from a bill of materials pasted from Excel. It adds steel with cutting waste, welding consumables and gas, painting, hours per stage, galvanizing and freight, then applies overhead and margin. The result is the total price and the price per pound, the figure the trade uses to compare quotes.

One line per item: description; type; unit weight; length or area; quantity; and, optionally, that item’s price per pound. For shapes, tubes and bars use type ft with the weight per foot from the AISC Manual or mill catalog (a W8x18 weighs 18 lb/ft). For plate use ft² with the weight per square foot (steel: 40.8 lb/ft² per inch of thickness). For bolts and anchors use lb with 1 as length.

The example has 7,982 lb of steel. Steel with 5% waste costs $7,219, welding (120 lb of wire and 479 ft³ of gas) $419, painting 998 ft² $1,497 and 198 crew hours $10,890. Direct cost is $20,925 ($2.62/lb) and the price, with 25% overhead and margin, comes to $27,900, or $3.50 per lb.

It varies a lot with the job: small pieces with lots of detail, welding and finishing cost far more per pound than heavy, repetitive framing, and erection at height adds cost. That is why the calculator builds the price from real costs instead of a flat rate per pound. After estimating, compare the $/lb with similar jobs you have done; big gaps usually come from hours, cutting waste or painting.

The safest source is your own history: hours logged on similar jobs divided by weight, in hours per ton. The example has 198 h for about 4 short tons, roughly 50 h per short ton, a common range for light welded structures. Without history, estimate stage by stage (cutting, fit-up, welding, finishing, erection) and update after each job.

Because overhead and margin are percentages of the selling price. With 10% overhead and 15% margin, 75% of the price is left to cover cost: $20,925 ÷ 0.75 = $27,900 (multiplier markup 1.333). Adding the 25% on cost would give $26,156, $1,744 less, and the real margin would land below 15%. US sales tax is normally added on the invoice, so the tax field defaults to zero.

Engineering, crane or lift rental, scaffolding, permits, financing of payment terms and site contingencies are not included; add them to overhead or as an outside-services line. Weight is theoretical from the catalog, without weld metal or galvanizing zinc. Sales tax treatment varies by state: check with your accountant.