How much extra should I allow for connections?

A standard allowance for connection plates, bolts, cleats, stiffeners, and base plates is 10-15% of the main steel weight. For simple structures with bolted connections, 10% is adequate. For complex fabrications with moment connections, haunches, or stiffeners, allow 15% or more. Your fabricator will provide exact figures from their shop drawings.

How do I find the weight per metre of a steel section?

The weight per metre is the last number in a steel section designation. For example, 254x146x37 UB weighs 37 kg/m. The full section properties are published in the Tata Steel Blue Book (SCI P363) and the Steel Construction Institute tables, available free online at steelconstruction.info.

Why do I need to know the total steelwork weight?

Total weight is needed for: (1) ordering steel from the stockholder, (2) planning crane lifts and erection sequence, (3) calculating transport requirements, (4) estimating costs (steelwork is priced per tonne for fabrication and erection), and (5) checking foundation loads. Under-estimating weight leads to budget overruns and crane hire problems.

What is the typical cost per tonne for structural steelwork in the UK?

In the UK (2025-2026), structural steelwork fabricated and erected typically costs between £2,500 and £4,000 per tonne, depending on complexity. Material only is around £800-£1,200 per tonne. Simple portal frames are at the lower end; complex multi-storey structures with moment connections are at the higher end. Always get specific quotes from fabricators.

Should I include the self-weight of steel in my structural calculations?

Yes, always include the self-weight of the steel members in your dead load calculations. For beams, the self-weight is typically 1-3% of the applied load and can usually be accommodated within design margins. For long-span or heavily loaded structures, the steel self-weight becomes more significant and must be explicitly included.

TradeCalculator

Steelwork Weight Calculator — Total Steel Tonnage Estimate

Calculate total steelwork weight from section catalogue data, including connection plate allowances. Essential for ordering, crane planning, and cost estimation.

Section Type

Select section catalogue or enter custom weight

Section Size

Weight per metre from Tata Blue Book

Number of Members

How many identical members

Member Length

Length of each member

How We Calculate This

This calculator estimates the total weight of structural steelwork by multiplying the catalogue weight per metre by member length and quantity, then adding a percentage allowance for connection components.

The formula

Total weight = (weight/m × length × quantity) × (1 + connection%)

Connection allowance

10%: Simple bolted connections, fin plates, cleats
12%: Standard commercial/industrial work
15%: Moment connections, haunches, stiffeners

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.