Construction glossary · Steel and structural

What is steel tonnagein construction?

Steel tonnage is the total weight of structural steel on a project, expressed in short tons of 2,000 pounds, calculated by summing each member's length times its weight per foot and adding an allowance for connections and details, commonly around 10 percent. It is the controlling quantity for pricing structural steel, because fabrication and erection are both quoted and billed per ton. Estimators compute it from the framing plans, column schedule, and the member designations on the structural drawings.

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Updated August 2026 · Reviewed by the Ruh construction team

1 ton = 2,000 lbPriced by $/ton erectedSummed from member weights

Pounds of steel to tons

The definition

Steel tonnage, explained.

Steel tonnage is the headline quantity for any structurally framed commercial building: the structural drawings list every beam, column, and brace by designation, and for rolled shapes (W, S, M, C, MC, HP) the number after the x is the weight in pounds per linear foot, so a W18x35 weighs 35 lb/ft. HSS, pipe, and angle callouts end in wall or leg thickness, not weight, so those unit weights come from the AISC Manual tables. The estimator multiplies each member length by its unit weight, sums the frame, and adds an allowance for connection material such as clip angles, shear tabs, plates, and bolts, commonly around 10 percent. Fabricators quote shop work per ton, erectors quote field labor and crane time per ton, and GCs sanity check steel bids in dollars per ton, so a bad tonnage number distorts everything downstream. New estimators get burned three ways: forgetting the connection allowance, mixing short tons with metric tonnes, and missing steel that hides off the framing plans, like frame-attached lintels and kickers shown only in sections and details. Tonnage also drives mill order lead times and erection crane sizing, so it surfaces again in scheduling and logistics, not just the bid.

How it is measured

Structural steel is taken off in pounds and priced in short tons of 2,000 lb. Quantities come from the structural framing plans, the column schedule, and the braced and moment frame elevations, with member designations supplying the lb/ft unit weight (the 35 in W18x35). The estimator runs length x lb/ft for every member, totals the pounds, then adds a connection and detail allowance, commonly around 10 percent, to cover plates, angles, stiffeners, and bolts that never appear as line items on the framing plan. The total converts to tons (divide by 2,000) and lands in the estimate as separate per-ton lines for material, fabrication, and erection, usually rounded up to the nearest tenth of a ton.

Worked example

A worked steel tonnage example.

Worked example

Frame a small warehouse roof with two member groups. Step 1, beams: 1,200 lf of W18x35 at 35 lb/ft, so 1,200 x 35 = 42,000 lb. Step 2, columns: 800 lf of W12x26 at 26 lb/ft, so 800 x 26 = 20,800 lb. Step 3, sum the members: 42,000 + 20,800 = 62,800 lb. Step 4, connection allowance at 10 percent: 62,800 x 0.10 = 6,280 lb, giving 62,800 + 6,280 = 69,080 lb. Step 5, convert to short tons: 69,080 / 2,000 = 34.54 tons, carried as 34.6 tons after rounding up to the nearest tenth. Step 6, price it: at an illustrative combined rate of $4,500 per ton for material, fabrication, and erection, 34.6 x $4,500 = $155,700. The 10 percent allowance is estimator judgment; the rest is straight measurement off the framing plans.

How Ruh handles it

How Ruh handles steel tonnage.

Ruh takes the contractor's structural set, pulls every beam, column, and brace off the framing plans and schedules, and runs the length x lb/ft math with a connection allowance to produce the project tonnage. It then prices those tons against the contractor's own price book, the per-ton fabrication and erection rates they actually pay, and returns a draft steel line. The estimator reviews the member list and the allowance, adjusts where the job warrants it, and signs off before the number goes into the bid.

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Steel tonnage: frequently asked questions

Is a 10 percent connection allowance always the right number?+

No, it is a starting point that moves with connection complexity. Simple shear-connected gravity framing can run lighter, while moment frames, braced bays with heavy gusset plates, and trusses can push the allowance well above 10 percent. The best calibration is your own history: compare detailed shop drawing weights against takeoff weights from past jobs and tune the factor by building type.

Are steel tons short tons or metric tonnes?+

In US commercial work, tonnage means short tons of 2,000 lb, and domestic fabricators and erectors price on that basis. A metric tonne is 2,204.6 lb, so mixing the two quietly shifts a steel number by about 10 percent. If material comes from a mill or importer quoting metric, convert before the quantity enters the estimate.

What steel is usually excluded from the structural tonnage?+

Steel deck is measured in square feet, open web joists are typically quoted by the joist manufacturer, and miscellaneous metals such as stairs, rails, loose lintels, and embeds usually carry their own Division 05 line items. The tonnage covers the structural frame, beams, girders, columns, braces, and their connection material, plus lintels and kickers attached to the frame, which the AISC Code of Standard Practice treats as structural steel. Fabricator scope letters spell out what is in and out, and a missed exclusion is a classic bid-day bust.

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The Steel and structural estimating cheat sheet

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Figures on this page are illustrative. Construction estimates depend on project-specific conditions, source documents, market pricing, and professional judgment. Ruh's AI assists the estimator and does not replace professional review: your team reviews, validates, and approves every estimate, bid, and pricing decision.

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What is steel tonnagein construction?

Steel tonnage, explained.

A worked steel tonnage example.

Worked example

How Ruh handles steel tonnage.

Steel tonnage: frequently asked questions

Related terms

Knowing what steel tonnage means is the easy half.

Try Ruh on a bid you are pricing now.

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