How is the mass per metre calculated?

It's the published nominal mass for the Australian section, taken from the manufacturers' tables: OneSteel (now InfraBuild) for hot-rolled and welded sections, angles and flat bar, Austube Mills for hollow sections, and Lysaght for C and Z purlins (their masses include the galvanising). For example, a 250UB25.7 is 25.7 kilograms per metre. Tees aren't in any free published table, so they take your supplier's figure.

What sections does the calculator cover?

Rolled beams and columns (UB, UC, PFC, welded WB and WC, and the older tapered flange 'RSJ' I-beams), hollow sections (SHS, RHS, CHS), equal and unequal angles (also offered as lintel and brick shelf angles), flat bar, and cold-formed C and Z purlins. Plate, flitch beam plates and fabricated box beams are worked out from the sizes you type. Tees and anything else not listed go in as Custom with your own name and kg/m.

How are plate and bolt masses worked out?

Plate mass uses 7,850 kg/m³, the density behind the published flat-bar tables (a 100 × 10 mm flat is 7.85 kg/m), so it is as exact as your plate sizes. Bolts use the mass per bolt you type in, because there is no single published figure: it changes with length, grade and the nuts and washers.

Why is cutting waste zero by default?

Structural steel is normally cut to length by the mill or supplier before delivery, so there is no on-site waste to allow for. Push the slider up if you're buying stock lengths and cutting on site, or if the fabricator's schedule shows offcuts you'll pay for.

How is the galvanising mass calculated?

AS/NZS 4680 sets a minimum average coating of 600 g of zinc per m² on steel over 6 mm thick (less on thinner steel). The calculator applies 600 g/m² to the steel surface area, worked out from each section's outside perimeter. The galvaniser weighs the real job, so treat it as a planning figure.

How are paint litres worked out?

A zinc phosphate primer covers about 5.8 m² per litre at a 50 µm dry film, and that figure allows for no losses. Multiply the surface area by the number of coats and divide by the coverage. Spraying and rough steel lose more, so check your product's data sheet.

Free calculator

Steel beam and column weight calculator

Steel section mass = length in metres × mass per metre (kg/m) × quantity. For 250UB25.7 that's 25.7 kg/m; a 6 m piece weighs 154 kg. Plates are area × thickness × 7,850 kg/m³. Add cutting waste, galvanising or paint on top.

Your job

Beams and columns

One line per section and length. Pick the type (the typical use shows underneath), then the size. Same piece repeated? Set the quantity. Not listed? Choose Custom and type its kg/m.

Beam

Type

Floor beams, roof beams, lintels, major horizontal spans.

Section

Length each

Qty

25.70 kg/m · 12.00 m total · 308 kg

Column

Type

Columns and posts, heavily loaded beams, portal frames.

Section

Length each

Qty

30.00 kg/m · 6.00 m total · 180 kg

Cutting waste

Wastage allowance0%

Structural steel usually arrives cut to length, so 0% is right most of the time. Add some if you're buying stock lengths and cutting on site.

Plates

Base plates, cleats, gussets and stiffeners. Mass is worked out at 7,850 kg/m³.

Bolts

Add bolts by size and count, with the mass per bolt from your supplier. Bolt mass changes with length, grade and the nuts and washers, so we don't guess it for you.

Coating

Optional

Your price per kg

Ask your steel supplier for a real rate. The greyed number is an example only and is never used in your result.

Members drawn to scale by length. Colour marks the section family.

Total mass

488kg

0.488 tonnes

Beams (1)

308kg

12.0 m of beam

Columns (1)

180kg

6.0 m of column

The working, with your numbers

1. Beams2×6×25.70= 308 kg
2. Columns2×3×30.00= 180 kg
3. Total masssections + plates + bolts + zinc= 488 kg

Typed those measurements in by hand?MetreMate measures them straight off your PDF plans. Free to start.

The formula, in plain words

1For each beam or column: mass = length (m) × quantity × mass per metre (kg/m) for that section.
2Beams total is the sum of every beam item; columns total is the sum of every column item.
3Plates: mass = area (m²) × thickness (mm) × 7,850 kg/m³ ÷ 1000. Multiply by quantity.
4Bolts: quantity × the mass per bolt your supplier gives you (it changes with length, grade, nuts and washers).
5Hot-dip galvanising: zinc ≈ 600 g per m² of steel surface, the AS/NZS 4680 minimum average for steel over 6 mm thick. Divide by 1000 for kilograms.
6Paint: litres = surface area (m²) × coats ÷ coverage. A zinc phosphate primer covers about 5.8 m² per litre at 50 µm dry film, before any losses.
7Plate strips, flitch plates and fabricated box beams: kg/m = steel cross-section area (mm²) ÷ 1,000,000 × 7,850. A box is two flanges plus two webs between them; a flitch beam counts only its steel plates, not the timber.
8Tees and custom sections use the kg/m you type in, from your supplier.
9Cutting waste is applied to the sections subtotal only, then plates, bolts and coating are added on top.

Worked example

Two 250UB25.7 floor beams at 6 m each, four 150UC30.0 columns at 3 m each, six 250 × 250 × 10 mm base plates, and twenty M20 bolts at 0.4 kg each (the supplier's figure). Hot-dip galvanised. Zero cutting waste.

1.Beams: 2 × 6 × 25.7 = 308.4 kg.
2.Columns: 4 × 3 × 30.0 = 360.0 kg.
3.Sections subtotal: 668.4 kg (0.668 t).
4.Plates (250 × 250 = 0.0625 m² each, 10 mm thick): 6 × 0.0625 × 10 mm × 7.85 = 29.4 kg.
5.Bolts: 20 × 0.4 = 8.0 kg.
6.Steel surface, from each section's outside perimeter: 12 m × 0.992 m²/m (250UB25.7) + 12 m × 0.928 m²/m (150UC30.0) = 23.0 m². Zinc: 23.0 × 600 ÷ 1000 = 13.8 kg.
7.Grand total: 668.4 + 29.4 + 8.0 + 13.8 = 719.6 kg (0.72 t).

Answer: About 720 kg including plates, bolts and the zinc from hot-dip galvanising.

How to measure it

Read the section off the engineer's structural drawing (e.g. 250UB25.7). Length is the cut length in metres.
Same section repeated on the plan? Set the quantity instead of adding multiple rows.
Add every base plate, cleat, gusset and stiffener under 'Plates' with its thickness and area.
Bolt sizes and counts come from the connection details on the drawing. Ask your supplier for the mass per bolt at your length.
For coating, leave 'Work out the surface area from the steel above' ticked, or untick it and type the fabricator's surface area.

Where the numbers come from

Every default in the calculator is a number a supplier or manufacturer publishes. We list the source next to it so you can check.

What	Value	Source
Mass per metre of UB, UC, WB, WC, PFC, EA, UA, flat bar and tapered flange beam (RSJ) sections	Published per section, e.g. 250UB25.7 = 25.7 kg/m	OneSteel (now InfraBuild) Hot Rolled and Structural Steel Products, 3rd edition (checked 2026-09-30)
Mass per metre of SHS, RHS, CHS sections	Published per section, e.g. 250UB25.7 = 25.7 kg/m	Austube Mills Product Availability Guide, Pipe and Tube Structural Products (checked 2026-09-30)
Mass per metre of C and Z purlins sections	Published per section, e.g. 250UB25.7 = 25.7 kg/m	Lysaght SupaPurlin (SupaZed and SupaCee) Design and Installation Manual, 2024 (checked 2026-09-30)
Density of steel, used for plate mass (a 100 x 10 mm flat is 7.85 kg/m)	7,850 kg/m³	OneSteel Hot Rolled and Structural Steel Products, Table 7 Flats (checked 2026-09-30)
Minimum average hot-dip galvanised coating on steel over 6 mm thick (AS/NZS 4680)	600 g of zinc per m²	Galvanizers Association of Australia, coating thickness to AS/NZS 4680 (checked 2026-09-30)
Zinc phosphate primer at 50 µm dry film, no losses allowed	5.8 m² per litre per coat	Dulux Protective Coatings, Luxaprime UMP data sheet (Nov 2023) (checked 2026-09-30)

Manufacturers named here are the source of the number, not a recommendation. Confirm quantities with your supplier.

Frequently asked questions

Stop typing measurements in by hand

MetreMate measures every wall, floor and roof straight off your PDF plan. Then it hands you the same numbers this calculator asks for.

Try MetreMate free