Steel Weight Calculator: Plate, Bar and Tube
The mass of a plate, flat bar, round bar, round tube or rectangular hollow section from its dimensions.
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How this calculator works
Mass is volume times density. For a plate or flat bar the cross-section is thickness times width. For round bar it is π d² / 4. For a hollow section it is the outer area minus the inner area, with the wall thickness taken off each side.
Carbon steel is about 7850 kg/m³, stainless steel about 8000 and aluminium about 2700. Rolled sections have rounded corners and tolerances, so the supplier's mass per metre is the better figure for ordering.
Formulas used
- m = \rho\,A\,L
- A_{round} = \frac{\pi d^2}{4}
- A_{hollow} = A_{outer} - A_{inner}
Worked example
With the default numbers in the calculator above:
- Cross-section area: 2000 mm²
- Mass per metre: 15.7 kg/m
- Mass of one piece: 94.2 kg
- Total mass: 94.2 kg
Change the numbers in the calculator to see the full working, every step, for your own case.
Common questions
What is the density of steel?
About 7850 kg/m³ for carbon steel.
Does it allow for rounded corners?
Yes. Square and rectangular hollow sections use rounded corners by default, which takes a few percent off the mass of a sharp-cornered section. You can choose sharp corners or type your own radius.
How do I find the mass of a plate in kilograms per square metre?
Multiply the thickness in millimetres by 7.85.
Related calculators
Further reading: Material suppliers' section tables.
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