Australian Steel Weight Calculator — UB, UC, PFC

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Australian Steel Mass Calculator

Calculate the total weight of Australian steel sections per AS/NZS 3679.1. The calculator uses standard mass per metre values from the Australian section database with density 7850 kg/m³. Weight estimation drives procurement quantities, transport logistics, crane selection, and cost forecasting — getting it right at the take-off stage prevents site delays and budget blowouts.

Supported Australian Sections

How to Use

  1. Select the Australian section type (UB, UC, PFC, angle, plate, or flat bar)
  2. Choose the specific section size from the AS/NZS 3679.1 database
  3. Enter the total length in metres (or number of pieces × length per piece)
  4. The calculator displays total mass (kg), total weight (kN), and mass per linear metre

Worked Example 1 — Beam Take-Off (UB)

Problem: Calculate the total steel weight for 12 × 8.0 m long 530UB92.4 primary beams in a commercial floor framing layout.

Solution (standard mass method):

Check via cross-sectional area:

Result: 8.87 tonnes of Grade 300 structural steel. Use this for transport booking (typically 15–20 t per truck), crane lift planning, and purchase order quantities.

Worked Example 2 — Base Plate Weight (Custom Plate)

Problem: 16 column base plates, each 450 mm × 450 mm × 25 mm thick, Grade 250 plate per AS/NZS 3678.

Solution:

Result: Order 667 kg of 25 mm Grade 250 plate. Always include a fabrication waste allowance — 5% for simple rectangular plates, 10–15% for profiled plates with internal cutouts.

Worked Example 3 — Mixed-Section Lot

Problem: A light industrial frame uses: 4 × 6.5 m 310UB40.4 columns, 6 × 9.2 m 460UB67.1 rafters, and 24 × 4.8 m 150PFC17.0 purlins. Estimate total steel tonnage.

Solution:

Columns:

Rafters:

Purlins:

Summary:

Component Section Qty × Length (m) Mass (kg)
Columns 310UB40.4 4 × 6.5 1,050
Rafters 460UB67.1 6 × 9.2 3,704
Purlins 150PFC17.0 24 × 4.8 1,958
Total 6,712 kg

Result: 6.71 tonnes total. Add 3% for connection material (end plates, stiffeners, cleats): ~6.9 tonnes order quantity.

Mass Tolerances — AS/NZS 3679.1

AS/NZS 3679.1 permits a mass tolerance of ±4% on the nominal mass per metre for individual sections. For take-off purposes:

The actual mass of any individual section varies within the ±4% tolerance band due to mill rolling practice. The cross-sectional area method (Ag × 7,850) typically agrees with the nominal mass within 1–2%.

Estimating Connection Weight

Connections add 3–8% to the main member weight, depending on the framing system:

Framing Type Connection Weight (% of member mass)
Simple shear connections (angle cleats, fin plates) 3–5%
Moment-resisting end plates 6–10%
Base plates with stiffeners 8–15% of column mass
Truss gusset plates 10–18% of chord mass

Include connection weight in the total take-off. A 50-tonne frame at 6% connection allowance requires an additional 3 tonnes of plate and angle stock.

Australian Steel Weight for Roof Purlins and Girts

Cold-formed purlins and girts are ubiquitous in Australian industrial and commercial construction. These are typically Z-section (Zeds) or C-section (Cees) members — lighter than hot-rolled PFCs and manufactured to AS/NZS 4600 (Cold-Formed Steel Structures).

Typical purlin spans for Australian portal frames (repeating):

Bay Spacing (m) Purlin Section Mass (kg/m) Typical Span (m) Unit Weight per Bay (kg)
6.0 Z20015 3.1 6.0 18.6
7.5 Z20019 4.1 7.5 30.8
9.0 Z25024 6.0 9.0 54.0
10.0 Z30030 8.6 10.0 86.0
12.0 Z35035 11.9 12.0 142.8

Purlins per portal bay rule of thumb: For a 30 m wide portal frame at 1.5 m purlin spacing, expect approximately 21 purlin lines. At 7.5 m bays with Z20019 purlins (4.1 kg/m), each bay contributes 21 × 7.5 × 4.1 = 646 kg of purlin steel. Over 10 bays this is 6.5 tonnes — typically 15–20% of the total frame weight.

Girts (wall cladding rails): For an 8 m eave height building, girts at 1.2 m spacing give 7 lines per side. At 9 m bays with Z20015 girts (3.1 kg/m), each wall bay = 7 × 9.0 × 2 sides × 3.1 = 391 kg of girt steel. Bridging and sag rods add approximately 8% to the purlin and girt weight.

Steel Tonnage Benchmarks — Australian Construction

Quick-reference estimates for preliminary budgeting (includes main members, connections, purlins, girts, and bracing):

Building Type Span (m) Eave Height (m) Bay Spacing (m) Steel kg/m² floor Typical Frame Type
Light industrial shed 20 4.5 6.0 18–24 Portal frame, UB rafters
Standard warehouse 30 7.0 7.5 28–38 Portal frame, WB/WC welded
Large distribution centre 45 10.0 9.0 40–55 Portal frame, plate web
Single-storey commercial (office) 15 3.6 7.5 35–45 Braced frame, UB/UC
Multi-storey car park 16 2.4 per level 8.0 55–70 Moment frame, UC columns
Mezzanine floor (within shed) 8 — 4.0 30–40 Simply supported UB beams

Note: kg/m² is gross floor area including all steelwork. Values are for normal soil conditions (N-class site). Add 10–15% for cyclonic regions (Regions C and D per AS/NZS 1170.2) due to heavier wind bracing requirements.

Density check for imported sections: Australian projects occasionally specify imported European or US sections. The density of structural steel is universally 7,850 kg/m³ regardless of origin, but the section mass per metre differs because of dimensional differences. Always use the AS/NZS 3679.1 database mass for locally sourced Australian steel — the nominal mass tolerances are calibrated to Australian mill practice, not European or US rolling tolerances.

Related Resources

FAQ

What density does the calculator use? Standard steel density of 7850 kg/m³ (7.85 t/m³) — consistent with AS/NZS 3679.1 and EN 10025. This is the accepted value for structural carbon steel. Stainless steel is denser at ~8000 kg/m³ and is not covered by this calculator.

Is the mass per metre the same as the section designation? Yes. Australian UB and UC sections carry their nominal mass in the designation: 530UB92.4 has a nominal mass of 92.4 kg/m, 310UB40.4 has 40.4 kg/m. This is different from US W-shapes where the designation is weight in lb/ft (W12×72 = 72 lb/ft). The calculator handles both naming conventions.

Can I calculate plate weight? Yes. Enter plate width, length, and thickness in millimetres. The calculator converts to metres, computes volume, and applies the standard density. For fabrication take-offs, add a waste allowance (typically 5–15% depending on shape complexity) on top of the calculator output.

Are UB/UC the same as European IPE/HEA sections? No. UB sections (Universal Beams) are a distinct series with different dimensional proportions from European IPE beams. UC sections (Universal Columns) have heavier flanges than HEA sections of comparable depth. Always select the correct regional code — the Australian database contains AS/NZS 3679.1 sections, the European database contains EN 10365 sections.

How accurate is the calculator for crane lift planning? The calculator provides the nominal steel weight. For crane sizing, the rigger should add the weight of: (a) lifting beam/spreader bar, (b) shackles and slings, (c) any attached cleats or brackets that were shop-welded, and (d) the upper-bound mass tolerance (+4%). The total lift weight is typically 110–120% of the nominal steel weight.

Does the calculator account for galvanising weight? No. Hot-dip galvanising adds approximately 3–7% to the section weight, depending on the section size and coating thickness per AS/NZS 4680. For galvanised steel, multiply the calculator output by 1.05 to approximate the coated weight. For precise values, use the coating mass from the galvaniser's certificate.

Design Resources

Educational reference only. Steel weight estimates are preliminary. Verify section masses against the current AS/NZS 3679.1 standard and mill certificates before procurement. Results are PRELIMINARY — NOT FOR CONSTRUCTION.