How to Calculate Metal Weight: Formulas, Examples and Free Calculator

Whether you are an engineer, fabricator, contractor or buyer, knowing the weight of steel and other metals is essential for quoting, ordering, transport and lifting. The good news: every metal weight calculation uses the same simple rule. This guide gives you the formula, the density of each common metal, a shortcut formula for every shape, worked examples, and a free calculator that does the maths for you.

The basic metal weight formula

Weight is simply volume multiplied by density. Because steel sizes are given in millimetres and lengths in metres, the easiest form of the formula is:

Weight (kg) = Area (mm²) × Length (m) × Density (g/cm³) ÷ 1000

So you only need three things: the cross-section area of the shape, the length, and the density of the metal. The area changes with the shape (plate, pipe, tube, angle, beam), which is why each shape has its own formula below.

Density of common metals

Metal	Density (g/cm³)	Density (kg/m³)
Mild steel / carbon steel	7.85	7,850
Stainless steel	8.00	8,000
Aluminium	2.70	2,700
Brass	8.50	8,500
Copper	8.90	8,900

These are the standard values used in our calculator. Exact density varies slightly with the grade or alloy, so treat results as theoretical weights.

Weight formula for each shape

Here is the cross-section area for each common shape, with a mild steel example for a 1 metre length.

Shape	Cross-section area (mm²)	Mild steel shortcut (kg per metre)	Example (1 m)
Plate / sheet	thickness × width	t × W × 0.00785	10 × 1000 mm = 78.50 kg
Round bar	π × D² ÷ 4	D² × 0.006165	50 mm = 15.41 kg
Round pipe	π × (OD − t) × t	(OD − t) × t × 0.02466	60 × 4 mm = 5.52 kg
Square / rectangular tube	2 × t × (W + H − 2t)	2t × (W + H − 2t) × 0.00785	50 × 50 × 3 mm = 4.43 kg
Equal angle	t × (2A − t)	t × (2A − t) × 0.00785	50 × 50 × 5 mm = 3.73 kg
H beam / I beam	2 × B × tf + (H − 2tf) × tw	area × 0.00785	100 × 100 × 6 mm = 13.56 kg

D = diameter, OD = outside diameter, t = thickness, W = width, H = height, A = leg length, B = flange width, tf = flange thickness, tw = web thickness. All sizes in mm.

For other metals, replace 7.85 with the density from the table above. For example, aluminium uses 2.70 instead of 7.85.

Worked examples

1. MS plate 2000 × 6000 × 10 mm

Weight = 2 m × 6 m × 10 mm × 7.85 = 942 kg per plate.

2. MS pipe 60 mm OD × 4 mm wall, 6 m long

Weight per metre = (60 − 4) × 4 × 0.02466 = 5.52 kg/m. For 6 m: 33.15 kg.

3. MS square tube 50 × 50 × 3 mm, 6 m long

Area = 2 × 3 × (50 + 50 − 6) = 564 mm². Weight per metre = 564 × 0.00785 = 4.43 kg/m. For 6 m: 26.56 kg.

4. Round bar 50 mm diameter, 6 m long

Weight per metre = 50² × 0.006165 = 15.41 kg/m. For 6 m: 92.48 kg.

5. Aluminium sheet 4 × 8 ft × 3 mm

Weight = 1.22 m × 2.44 m × 3 mm × 2.70 = 24.11 kg per sheet.

How to use the SteelCal metal weight calculator

Our free metal weight calculator does all of these formulas for you, instantly, as you type:

1. Choose the shape: plate or sheet, round bar, round pipe, square or rectangular tube, equal angle, or H/I beam.
2. Choose the material: mild steel, stainless steel, aluminium, brass or copper.
3. Enter the sizes in millimetres (for example thickness and width, or outside diameter and wall).
4. Enter the length in metres and the quantity of pieces.
5. Read the result: weight per metre and total weight in kg, updated as you type.

It works on mobile too, so you can check weights on site or in the workshop. The calculator is also available in the sidebar of our blog pages.

Why actual weight can differ from the calculation

• Rolling tolerance: mills produce steel within a thickness tolerance, so real plates and sections can be slightly heavier or lighter.
• Rounded corners: hot-rolled beams, channels and angles have root radii that the simple formulas ignore.
• Coatings: galvanizing adds a layer of zinc, so GI products weigh a little more than plain steel of the same size.
• Chequered plate: the raised pattern adds weight on top of the base plate thickness.

For standard sections such as beams and channels, use the published weight per metre from section tables, like those on our product pages.

Weight charts for common steel products

Need ready-made figures? These pages have weight charts in kg per metre or per sheet:

• MS plate weight chart and chequered plate
• MS pipe weight chart and GI pipe
• MS square and rectangular tube weight chart
• I beam, UB and UC weight chart and HEA and HEB beams
• MS angle, U channel and flat bar
• GI mesh and BRC mesh

Frequently asked questions

How do you calculate the weight of steel?

Multiply the cross-section area in mm² by the length in metres and by 7.85, then divide by 1000. The result is the weight in kg.

What is the density of mild steel?

7.85 g/cm³, which is 7,850 kg/m³. Stainless steel is about 8.00 g/cm³ and aluminium about 2.70 g/cm³.

How do I calculate steel plate weight?

Weight (kg) = length (m) × width (m) × thickness (mm) × 7.85. A 2000 × 6000 × 10 mm plate weighs 942 kg.

How do I calculate MS pipe weight per metre?

Use (OD − t) × t × 0.02466, with OD and wall thickness t in mm. A 60 × 4 mm pipe weighs 5.52 kg per metre.

Why is 0.006165 used for round bar weight?

It equals π ÷ 4 × 7.85 ÷ 1000, so diameter² × 0.006165 gives the weight of a round steel bar in kg per metre.