Steel Weight Calculator — Bars, Tubes & Sections
Select a section profile (round bar, square, flat, tube, hex), enter the key dimensions and length in mm, choose the material, and get the weight in kilograms per piece and per metre.
Section type
mm
mm
Material
Single bar or section at the chosen density
15.41 kg
- 1
Cross-section area
π ÷ 4 × 50² = 1,963.5 mm² - 2
Volume
1,963.5 mm² × 1,000 mm ÷ 10⁹ = 0.001963495 m³ - 3
Weight per piece
0.001963495 m³ × 7,850 kg/m³ = 15.413
How does this calculator work?
Weight = cross-section area (mm²) × length (mm) × density ÷ 10⁹. For a 50 mm mild-steel round bar 1,000 mm long: area = π/4 × 50² ≈ 1,963 mm², weight ≈ 1,963 × 1,000 × 7,850 ÷ 10⁹ ≈ 15.4 kg. Supports round, square, flat, tube and hex bar profiles.
Formula
How this is calculated
Every steel section has a cross-sectional area that depends on its profile. For a solid round bar the area is π/4 × d²; for a square bar it is a²; for a flat (rectangular) bar it is width × height; for a round hollow tube it is π/4 × (OD² − ID²) where ID = OD − 2 × wall thickness; and for a hexagonal bar (specified by across-flats dimension AF) the area is (√3/2) × AF². Multiplying the cross-section area (mm²) by the length (mm) gives volume in mm³, and dividing by 10⁹ converts to m³. Multiplying by density (kg/m³) gives kilograms.
Mild steel density is approximately 7,850 kg/m³ — the standard value used for structural and manufacturing estimates. Stainless 304 and 316 are slightly denser due to their alloy additions, while aluminium 6061 is roughly one-third the density of steel. These are reference values; for precision work, consult the material test certificate.
The weight-per-metre figure (kg/m) is widely used in fabrication shops and steel stockists for pricing and procurement. Multiply the single-piece weight by quantity to get the total shipping or cutting weight.
Frequently asked questions
The cross-section area of a round hollow tube is π/4 × (OD² − ID²), where ID = OD − 2 × wall thickness. This net area is multiplied by length and density. For example, a 60 mm OD tube with 5 mm wall (ID = 50 mm) has area = π/4 × (3600 − 2500) = 864 mm².
Across-flats (AF, also called width-across-flats or WAF) is the distance between two opposite flat faces of the hexagon — the standard commercial specification. The cross-section area is (√3/2) × AF², e.g. AF = 30 mm gives area ≈ 779 mm².
The calculation uses nominal (reference) densities. Real bars may differ by ±1–2% due to alloy variation, rolling tolerances and surface condition. For exact quantities in procurement, use certified mill test reports or weigh the bar directly.
Also known as
TG we-Calculate Editorial Team. (2026). Steel Weight Calculator — Bars, Tubes & Sections [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/steel-weight-calculator
TG we-Calculate Editorial Team. "Steel Weight Calculator — Bars, Tubes & Sections." TG we-Calculate. 2026. https://we-calculate.com/calculator/steel-weight-calculator.
TG we-Calculate Editorial Team, "Steel Weight Calculator — Bars, Tubes & Sections," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/steel-weight-calculator
@misc{wecalculate_steel_weight_calculator, title = {Steel Weight Calculator — Bars, Tubes & Sections}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/steel-weight-calculator}}, year = {2026}, note = {TG we-Calculate} }
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