Steel Weight Calculator
The plate before the project — length, width, thickness into kilograms at steel's honest 7,850 kg per cubic metre.
Steel Weight Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Nominal density — no alloy or mill-tolerance spread
- Flat plate arithmetic; sections use their own tables
In short: A 2 by 1 metre plate at 10 mm weighs 157 kg — the quickest mental check in the trade being 7.85 kg for every square metre, per millimetre of thickness. Two square metres at ten millimetres: 157, on the nose. A tonne is six and a third of these sheets, which is why the delivery truck appeared before the crane did. The number the billing office wants and the number the crane operator wants turn out to be the same number.
Formula
kg = L × W × t(mm) × 7.85 × 10⁻⁶
Steel weighs 7,850 kg per cubic metre, so a millimetre of thickness on a square metre is 7.85 kg — the constant every steel yard quotes from memory. Length times width times thickness in millimetres times 7.85 millionths is the kilogram answer. The same density prices bars: a round bar runs about d-squared over 162 kilograms per metre, the square bar a shade over d-squared over 127.
Worked Example
- Enter the plate's length, width and call-out.
- Read the kilograms — and the sheets to the tonne.
- Let the crane plan and the invoice agree.
Defaults: 2,000 × 1,000 × 10 — 157 kg, 78.5 kg per square metre, six and a third sheets to the tonne. Thicken the same plate to 20 mm and every number doubles.
Strengths & Limits Of This Model
Where this engine is strong
- The 7.85 constant is on the page, verifiable
- Sheets-to-the-tonne for orders and cranes alike
Where it stops
- Cut shapes with holes need the volume net of them
Practical Use Cases
Material orders
kilograms before the quote
Crane plans
what the lift really weighs
Shipping
the freight line nobody budgets
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Steel Weight Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is the quickest mental check?
Seven point eight five kilograms for every square metre, per millimetre of thickness. Ten millimetre plate: 78.5 kg/m². Six millimetre: 47.1. The constant survives every yard conversation.
How do I weigh a round bar?
About d-squared over 162 kilograms per metre for diameter in millimetres — a 20 mm bar runs 2.47 kg/m. Same density, different geometry; the plate formula needs volume, the bar shortcut folds it in.
Does stainless weigh the same?
Close — about 7,900 kg per cubic metre, half a percent over carbon steel. For orders and lifts the carbon answer carries; for laboratory work the alloy's own density does.
Why does the mill tolerance matter?
Plates ship a tolerance either side of the call-out thickness, and on a tonne order that is real kilograms — real freight charges too. The answer is nominal; the scale at the gate is actual.
How much does a tonne of this plate cover?
Six and a third sheets of the default size. Flip it around: a floor of 100 m² at 10 mm wants 7,850 kg — nearly eight tonnes before a single stiffener.
Is the density the same for sections and plate?
Yes — density does not care about the shape. Sections are weighed per metre from their own tables, but any cut piece, gusset or drop is plate arithmetic on its volume.
What unit errors are most common?
Millimetres into the formula with metre instincts on the volume. Length, width and thickness all in millimetres times 7.85 millionths lands on kilograms; mixing one metre in multiplies the answer a thousandfold.
Where does this number matter most?
Twice: the invoice and the lift plan. Between them sits the design — the concrete page orders the slab this plate reinforces, and the bending stress page says why the two share the load.