Steel Weight Calculator

Calculate the total weight of structural steel members from unit mass, length, and quantity. Enter multiple items for a full material take-off. Results update live with a per-item breakdown.

How It Works

Every structural steel section has a published unit mass — the weight per unit length. This value accounts for the full cross-section including flanges, web, and fillet radii. Total weight is simply:

Unit mass is found in manufacturer section tables and design handbooks. For example, a 610 UB 125 has a unit mass of 125 kg/m — meaning each metre of that beam weighs 125 kg. The equivalent US section (W24×84) weighs 84 lb/ft.

Common Section Weights

Reference table of unit masses for commonly used structural steel sections. Values are nominal and sourced from AS/NZS, BS/EN, and AISC section catalogues.

Unit Mass vs Calculated Weight

Published unit masses are based on nominal dimensions and a steel density of 7850 kg/m³ (0.2836 lb/in³). Actual weights may vary slightly due to rolling tolerances — typically within ±2.5% for hot-rolled sections. For estimation and material ordering, nominal values are standard practice.

Calculating from Dimensions

If you don't have a published unit mass — for example, for a steel plate or a non-standard built-up section — you can calculate it from cross-sectional area:

For a simple rectangular plate:

For example, a 200 mm × 10 mm flat plate weighs 200 × 10 × 0.00785 = 15.7 kg/m.

Material Take-Off Tips

• Allow 3–5% extra for connections, stiffeners, and waste
• Include gusset plates, base plates, and cleats as separate line items
• For bolted connections, bolt weight is typically negligible (<1% of total)
• Round up to the nearest standard length — steel is sold in stock lengths (6 m, 9 m, 12 m / 20 ft, 30 ft, 40 ft)
• For painted or galvanised steel, coating weight adds approximately 0.5–1.5%

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