Steel Weight Calculator — Weight Per Foot for All Steel Sections

Steel weight is the primary cost driver in structural steel construction. Material cost is 50-60% of the total erected steel cost, and fabrication, delivery, and erection are all proportional to weight. This reference provides weight per foot (and per meter) for all common structural steel shapes, the formulas to calculate weight for custom sections, and total weight estimation for steel buildings.

How to calculate steel weight

Universal formula

All structural steel has a density of 7850 kg/m^3 (490 lb/ft^3, 0.2836 lb/in^3). The weight per unit length is:

Weight (lb/ft) = Area (in^2) x 3.402
Weight (kg/m)  = Area (mm^2) x 0.00785

Where 3.402 = 0.2836 lb/in^3 x 12 in/ft, and 0.00785 = 7850 kg/m^3 / 1,000,000 mm^2/m^2.

Quick reference: area to weight conversion

W-shape weight table

Light W-shapes (beams)

Heavy W-shapes (columns)

HSS weight table

Square HSS

Rectangular HSS

Round HSS (pipe)

Steel angle weight table

Equal angles (L)

Steel channel weight table

Steel plate weight table

Formula: Weight per square foot (psf) = thickness (in.) x 40.84.

Steel building weight estimation

Typical structural steel weights by building type

Structural steel weight per square foot of floor area. Includes beams, columns, braces, connections (add 10% for connections to member weights). Does not include deck, slab, or cladding.

Weight breakdown by component (typical office building)

Worked example — total steel weight estimate

Building: 5-story office, 100 ft x 200 ft plan (10,000 SF per floor, 50,000 SF total). Bay size 30 ft x 30 ft, with 10 ft floor-to-floor height.

Step 1 — Typical floor beam (30 ft span at 10 ft spacing):

W21x44 at 44 lb/ft x 30 ft = 1,320 lb per beam. 20 beams per floor x 5 floors = 100 beams. Floor beam total = 100 x 1,320 = 132,000 lb.

Step 2 — Girders (30 ft span carrying 2 beams each):

W24x55 at 55 lb/ft x 30 ft = 1,650 lb per girder. 10 girders per floor x 5 floors = 50 girders. Girder total = 50 x 1,650 = 82,500 lb.

Step 3 — Columns (approx 50 ft total height, 16 columns):

Average W14x120 at 120 lb/ft x 50 ft = 6,000 lb per column. 16 columns. Column total = 16 x 6,000 = 96,000 lb.

Step 4 — Roof framing (lighter than floors):

W18x35 at 35 lb/ft x 30 ft = 1,050 lb per beam. 20 beams. Roof beam total = 20 x 1,050 = 21,000 lb.

Step 5 — Bracing and connections (add 20%):

Subtotal = 132,000 + 82,500 + 96,000 + 21,000 = 331,500 lb. Connections + bracing = 331,500 x 0.20 = 66,300 lb.

Total structural steel: 331,500 + 66,300 = 397,800 lb = 199 tons.

Weight per SF = 397,800 / 50,000 = 7.96 psf (structural steel only, per total building floor area including roof). Weight per SF of floor = 397,800 / 50,000 = 7.96 psf. This is consistent with the 5-story office estimate of 14-18 psf if counted per floor area only (the psf is lower here because the building is relatively light).

Cross-code weight calculation

All use the same steel density. The difference is only in unit systems.

Steel Density by Grade

While all carbon structural steels (A36, A572, A992, A500, A588) share the same density of 7850 kg/m³ (490 lb/ft³), different steel types have varying densities due to alloy content:

For most structural calculations, use 7850 kg/m³ (490 lb/ft³). The 2% difference for stainless steel is significant for weight-critical applications (offshore platforms, architectural steel) but negligible for ordinary building design.

Round Bar, Square Bar, and Flat Bar Weight

Round Bar (Solid)

Weight per foot: W = d² × 0.2227 (d = diameter in inches) Weight per meter: W = d² × 0.006165 (d = diameter in mm)

Where 0.2227 = pi/4 × 490/1728 × 12 (conversion from in³/ft to lb/ft with density 490 lb/ft³).

Square Bar

Weight per foot: W = s² × 0.2836 (s = side length in inches) Weight per meter: W = s² × 0.00785 (s = side length in mm)

Flat Bar

Weight per foot: W = w × t × 3.40 (w = width in inches, t = thickness in inches) Weight per meter: W = w × t × 7.85 (w = width in mm, t = thickness in mm)

For a flat bar 4 in wide x 1/2 in thick, weight per ft = 4 × 0.5 × 3.40 = 6.80 lb/ft. For metric: 100 mm x 12 mm plate bar, weight/m = 100 × 12 × 7.85/1000 = 9.42 kg/m.

Unit Conversion Reference

Quick steel conversion: A steel section with weight w lb/ft has mass m = w × 1.488 kg/m. A W21x44 beam weighs 44 lb/ft = 44 × 1.488 = 65.5 kg/m. A W310x97 column weighs 97 kg/m = 97 × 0.672 = 65.2 lb/ft.

Common mistakes to avoid

1. Forgetting connection weight. Connections (clip angles, end plates, gusset plates, stiffeners, bolt holes) add 8-12% to the member-only steel weight. Estimate connection weight as 10% of total member weight for preliminary costing.

2. Using nominal section weight for pricing. Mill tolerances allow actual weight to vary +/4% from the nominal. For precise weight, use the actual area from AISC Table 1-1 rather than the nominal lb/ft designation.

3. Ignoring waste factor. Order 3-5% more steel than calculated to account for cutoffs, test specimens, and field modifications. For renovation projects, use 5-8%.

4. Not accounting for camber and mill tolerances. Cambered beams are cut longer than straight beams to compensate for the camber. The weight per foot is the same, but the total length (and thus total weight) may differ from the plan dimension.

5. Confusing structural steel weight with total building steel. Structural steel excludes reinforcing steel (rebar), steel deck, steel joists, metal stairs, handrails, and miscellaneous metals. Each is priced separately.

6. Using wrong density for stainless or weathering steel. Austenitic stainless steel (304, 316) has a density of 8000 kg/m^3 (2% heavier than carbon steel). Weathering steel (A588, A847) has the same density as carbon steel (7850 kg/m^3).

Frequently asked questions

How much does structural steel weigh per square foot? For typical office buildings, structural steel weighs 12-18 psf of floor area. Warehouses are lighter (6-10 psf). High-rise buildings are heavier (18-28 psf). These values include beams, columns, and bracing but exclude connections, deck, and concrete.

How do I calculate the weight of a steel beam? Multiply the weight per foot (from the AISC table) by the beam length. For a W21x44 spanning 30 ft: 44 lb/ft x 30 ft = 1,320 lb. Add 10% for connections (clip angles, bolts, welds).

What is the density of structural steel? 7850 kg/m^3 (490 lb/ft^3, 0.2836 lb/in^3). This is the same for all carbon structural steels (A36, A572, A992, A500, A588). Stainless steel is slightly heavier at 8000 kg/m^3.

How much does a steel column weigh? A typical W14 column weighs 60-200 lb/ft depending on loading. A 15-story column might be W14x159 at the base (159 lb/ft) and W14x48 at the top (48 lb/ft), averaging about 100 lb/ft. For 15 stories at 13 ft each = 195 ft: 100 x 195 = 19,500 lb per column.

How do I estimate steel weight for a building? Multiply the gross floor area by the steel weight per square foot (from the table above). For a 5-story, 50,000 SF office building at 15 psf: 50,000 x 15 = 750,000 lb = 375 tons. Add 5% for waste = 394 tons.

What is the difference between weight and mass in steel design? Weight (force) = mass x gravity. In imperial units, the lb/ft value from AISC tables is technically a mass per unit length (lb_m/ft). In structural calculations, we use it directly as a force per unit length (lb_f/ft) because 1 lb_m = 1 lb_f under standard gravity. In metric, 1 kg mass = 9.81 N force, so a W310x107 weighs 107 kg/m = 1050 N/m = 1.05 kN/m.

How much does a round steel bar weigh per foot? Round steel bar weight is calculated from the cross-sectional area: W = (pi x d²/4) x 3.40 lb/ft per in² = d² x 0.2227, where d is the diameter in inches. For a 1-inch diameter bar: W = 1² x 0.2227 = 2.67 lb/ft. For metric: W = d² x 0.006165, where d is in mm. A 25 mm bar: W = 25² x 0.006165 = 3.85 kg/m. Bar weight tables are used for machined parts, anchor rods, reinforcing bars, and custom fabrication takeoffs.

What is the difference between carbon steel and stainless steel density? Carbon structural steel (A36, A572, A992) has density 7850 kg/m³ (490 lb/ft³). Austenitic stainless steels (304, 316) have density 8000 kg/m³ (499 lb/ft³) — about 2% heavier due to higher chromium and nickel content. Martensitic stainless (410) is lighter at 7800 kg/m³ (487 lb/ft³). For a typical 10-ton carbon steel structure, using stainless would add about 200 kg of weight. This difference matters for offshore platforms (where weight drives floatation), architectural steel (where deflection from self-weight changes), and cost estimating (stainless costs 3-5x more per kg).

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• Section Properties Database
• Beam Calculator

Related references

• Structural Steel Weights
• Steel Section Types
• Beam Sizes
• HSS Section Properties
• Steel Angle Sizes
• Steel Channel Sizes
• Steel Material Properties
• Steel Construction Costs
• How to Verify Calculations

Disclaimer

This page is for educational and reference use only. It does not constitute professional engineering advice. All design values must be verified against the applicable standard and project specification before use. The site operator disclaims liability for any loss arising from this information.