Metal Weight Calculator
Cross-sectional area and mass for any of 16 materials and 10 section shapes. Nothing here is read from a table: area comes from the shape's geometry, so the answer is exact for the dimensions you enter rather than approximate for the nearest stock size.
Bill of materials
Reverse lookup
How much length reaches a target mass? Uses the first line above.
Formula
A = π/4 · d²
A = π/4 × d², where d is the outside diameter
Mass = area × length × density. Every result on this page is computed that way; the geometry is never looked up.
Reference dimensions in carbon steel
The ten shapes at their reference dimensions, so this page is useful without running any script. Change the material above to see how density alone moves every figure.
| Shape | Reference dimensions | Cross-section | Mass / length | Imperial |
|---|---|---|---|---|
| Round Bar | d 25 mm | 490.9 mm² | 3.853 kg/m | 2.589 lb/ft |
| Square Bar | a 25 mm | 625.0 mm² | 4.906 kg/m | 3.297 lb/ft |
| Hexagonal Bar | AF 24 mm | 498.8 mm² | 3.916 kg/m | 2.631 lb/ft |
| Flat Bar | w 50 × t 6 mm | 300.0 mm² | 2.355 kg/m | 1.582 lb/ft |
| Plate | w 1000 × t 10 mm | 10,000.0 mm² | 78.500 kg/m | 52.750 lb/ft |
| Round Tube | D 50 × t 3 mm | 443.0 mm² | 3.477 kg/m | 2.337 lb/ft |
| Square Tube | a 40 × t 3 mm | 444.0 mm² | 3.485 kg/m | 2.342 lb/ft |
| Rectangular Tube | a 60 × b 40 × t 3 mm | 564.0 mm² | 4.427 kg/m | 2.975 lb/ft |
| Angle (L Section) | a 50 × b 50 × t 5 mm | 475.0 mm² | 3.729 kg/m | 2.506 lb/ft |
| Channel (U Section) | h 200 × b 75 × t_w 8 × t_f 10 mm | 2,940.0 mm² | 23.079 kg/m | 15.508 lb/ft |
Reference dimensions are the defaults each calculator field starts from. Enter your own dimensions above to compute a real part.
How to read the results
Cross-sectional area is what you feed into a stress or deflection calculation. It depends only on geometry, so it does not change when you change material.
Mass per unit length is what you feed into an order. It is the area multiplied by density, so it changes with material and nothing else.
Total mass is per-unit mass × length × quantity. Check the quantity column before trusting a total: it is the single most common source of a wrong number in a take-off, and it is not a rounding problem.
Frequently asked questions
How is metal weight calculated?
Weight is cross-sectional area multiplied by length multiplied by density. The area comes from the closed-form geometry of the shape — for a round bar, π/4 × d²; for a hollow section, the outer area minus the inner area. Nothing on this page is read from a lookup table, which is why the calculator is exact for whatever dimensions you enter.
Why does my supplier’s weight table disagree in the last digit?
Almost always density. Printed weight tables for steel are usually calculated at a nominal 0.2836 lb/in³ (about 7,850 kg/m³) or, on some charts, a rounded 0.2833 lb/in³. We use the real specification density for the material you select, so a 304 stainless figure will be 1.9 % heavier than the carbon steel figure for identical geometry.
Can I calculate a whole bill of materials at once?
Yes. Add a line for each different section — the material selector applies to the whole list, which matches how a take-off works in practice: one material call-out, many sections. The list can be copied or downloaded as CSV.
What is the reverse lookup for?
It answers the question the forward calculation cannot: given a mass limit, how many metres of this section can I use? Enter the limit and the calculator returns the length that reaches it. This is the constraint that actually governs a lot of fabrication work — crane capacity, shipping weight bands, axle limits — and it is not something a printed table can answer at all.
Does weight tell me whether the part is strong enough?
No. Weight is a mass property; strength and stiffness are different calculations that need the second moment of area, the material’s yield strength and the load case. This page will tell you what your part weighs and what its cross-sectional area is — the two inputs a stress calculation needs — and nothing more.
Related reference data
Weight is only half of a part’s description. These pages cover the geometry and the data behind it.
- Metal weight overview — how the calculation works
- Density chart — lightest to heaviest
- Pipe weight calculator — any OD and wall
- Methodology and sources — where every number comes from
Areas are closed-form geometry. Densities are nominal values from the material specifications named on each material page. Unit factors are definitional constants.
- Elementary plane geometry. The circle, polygon and hollow-section area formulas.
- ASTM material specifications for each grade named in the material entry (A36, A240/A276, B209/B211/B221, B152/B16/B505, B265/B348, A48, B29, D1784, D3350).
- BIPM / NIST definitional constants: international inch = 25.4 mm, foot = 0.3048 m, pound = 0.45359237 kg.
Dataset version 2026.09.1 · dimensions last verified against source 2026-09-21. Found an error? Report it — corrections are issued with a version bump.