Steel Weight Calculator
Estimate the weight of flat steel plates and rectangular sections from four inputs: length in metres, width in millimetres, thickness in millimetres, and quantity. The result in kilograms helps you compare plate options, plan handling, and build a material list before requesting quotes.
Your result will appear here.
Steel Weight Calculator online
Estimate the weight of a rectangular steel plate or block from its dimensions and quantity at the standard 7,850 kg/m³ density — for quotes, freight and workshop planning.
How it works
The tool treats the piece as a rectangular block: weight = length(m) × (width(mm)/1000) × (thickness(mm)/1000) × quantity × 7850. Dividing width and thickness by 1000 converts them to metres, giving a volume in cubic metres, which is multiplied by the standard density of carbon steel, 7850 kg/m³. Length stays in metres, so a 2 m plate that is 1000 mm wide and 10 mm thick has a volume of 2 × 1.0 × 0.01 = 0.02 m³.
Worked example
One mild-steel plate 2 m long, 1000 mm wide, 10 mm thick: volume = 2 × (1000/1000) × (10/1000) = 2 × 1.0 × 0.01 = 0.02 m³. Weight = 0.02 × 7850 = 157.0 kg. Ordering 5 identical plates: 157.0 × 5 = 785.0 kg. A thinner 6 mm plate of the same footprint weighs 2 × 1.0 × 0.006 × 7850 = 94.2 kg, which shows why thickness dominates the total.
Units
Width and thickness are entered in millimetres; length in metres; output in kilograms. A useful shortcut: 1 m² of steel plate weighs about 7.85 kg per millimetre of thickness, so 1 m² of 10 mm plate ≈ 78.5 kg. Divide kilograms by 1000 for tonnes.
Practical tips
- Double-check which face is the length. Entering 2000 as metres instead of millimetres inflates the result a thousandfold.
- For chequered or coated plate, the tool gives the plain-plate weight; add the coating or pattern allowance from the mill certificate if you need billed weight.
- Round up piece counts for cutting frames and test coupons, and confirm crane and transport limits against the per-piece weight, not just the total.
- Use this figure for budgeting and logistics only; connection design, grade selection and allowable stresses need review by a competent structural professional.
Edge cases and limitations
- Beyond rectangles. The block formula covers plate and flat bar. For round bar, the same steel gives kg per metre = d² ÷ 162 (a 20 mm bar is about 2.47 kg/m); for pipe, use π × (D − t) × t × 0.02466 kg per metre with D and t in mm (a 100 mm OD, 5 mm wall pipe is about 11.7 kg/m). Universal beams and channels follow their tabulated kg/m — no rectangle approximates a section well.
- Mill tolerance fattens plates. Plate is rolled to a thickness tolerance and is often delivered 2–5% over nominal weight; invoices are frequently by scale weight. A theoretical 785 kg order arriving as 810 kg is normal, not a short-change.
- Galvanizing adds a skin. A hot-dip zinc coating typically adds roughly 5% to the finished weight of light fabrications (more surface per tonne, more zinc). Quote galvanized work on the coated weight.
- Other metals, same shape. The volume math is metal-agnostic: swap 7,850 for 2,700 (aluminium) or 8,960 (copper) and the block calculation holds — but this page's density is fixed to steel, so rescale the result by the density ratio.
Privacy and browser processing
The calculation runs entirely in your browser — the dimensions you enter are never uploaded.
Frequently asked questions
Why does the tool use 7850 kg/m³?
7850 kg/m³ is the accepted density of carbon structural steel. Stainless grades differ slightly (around 7900–8000 kg/m³), so for stainless work multiply the tool result by roughly 1.01–1.02 or confirm the grade density on the mill sheet.
How much does a 2 m × 1 m × 10 mm plate weigh?
Volume = 2 × 1.0 × 0.01 = 0.02 m³, and 0.02 × 7850 = 157 kg. Two such plates weigh 314 kg.
Can I use this for round bar or pipe?
No. This page assumes a rectangular cross-section (width × thickness). Round bars need the π/4 × d² area formula, and hollow sections need outside minus inside area — use the rebar calculator for solid round bars instead.
Do I enter width in mm or metres?
Millimetres. Entering 1 instead of 1000 for a one-metre-wide plate understates the weight by a factor of 1000 (0.157 kg instead of 157 kg), so always check the unit label beside each field.