Steel Weight Calculator
Calculate the weight of steel bars, plates, tubes and sections.
Please note: Material estimates for planning only. Always confirm quantities against your drawings, local building codes and supplier specifications before ordering. Structural work requires a qualified engineer.
What the Steel Weight Calculator does
Steel weight is cross-sectional area multiplied by length and density. Hollow sections subtract the bore from the outside area, which is why a tube weighs far less than a solid bar of the same diameter.
Formula
Round bar area = π × (D ÷ 2)²Tube area = π × ((D ÷ 2)² − (D ÷ 2 − Wall)²)Weight = Area × Length × Density × Pieces
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Steel shape | one of 5 options | Yes | — |
| Diameter | mm | In some modes | Accepts 0.1 or more. Shown Steel shape is Round bar, or Steel shape is Round tube or pipe. |
| Side length | mm | In some modes | Accepts 0.1 or more. Shown Steel shape is Square bar. |
| Width | mm | In some modes | Accepts 0.1 or more. Shown Steel shape is Flat bar or plate, or Steel shape is Rectangular tube. |
| Height or thickness | mm | In some modes | Accepts 0.1 or more. Shown Steel shape is Flat bar or plate, or Steel shape is Rectangular tube. |
| Wall thickness | mm | In some modes | Accepts 0.1 or more. Shown Steel shape is Round tube or pipe, or Steel shape is Rectangular tube. |
| Length | number | Yes | Accepts more than 0. |
| Length unit | one of 6 options | Yes | — |
| Number of pieces | number | Yes | Accepts 1 or more. |
| Material density | kg/m³ | Yes | Steel 7850, aluminium 2700, stainless 8000. Accepts 100 or more. |
| Price per kg | selected currency | Optional | Accepts 0 or more. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Steel shape and Length unit.
- Enter Length, Number of pieces and Material density.
- Fill in the remaining inputs the form shows for your choice.
- Optionally add Price per kg.
- Select Calculate.
Worked example
A 20 mm round steel bar, 6 m long, one piece, 7,850 kg/m³.
- Shape
- Round bar
- Diameter
- 20 mm
- Length
- 6 m
- Density
- 7850
Area 314.16 mm², volume 0.001885 m³ → 14.8 kg, or 2.466 kg per metre.
Frequently asked questions
Does this match the d²/162 rebar formula?
Yes. For steel at 7,850 kg/m³, π/4 × d² × 7850 simplifies to almost exactly d²/162 with d in millimetres.
What density should I use for other metals?
Aluminium 2,700 kg/m³, brass 8,500, copper 8,960, stainless steel about 8,000.