What formula is used for a square tube?

Weight = (Outer Side² − Inner Side²) × Length × Density, where Inner Side = Outer Side − 2 × Wall Thickness. All dimensions are converted to meters and multiplied by the iron density of 7874 kg/m³ to obtain kilograms.

What iron density does this calculator use?

A density of 7874 kg/m³ is used. This is the standard value for pure iron. Mild steel is typically 7850–7870 kg/m³, so results are very close and appropriate for most structural iron and steel square tube applications.

How is the inner side dimension determined?

Inner Side = Outer Side − 2 × Wall Thickness. For example, a 100 mm outer side tube with 5 mm walls has an inner side of 90 mm. The calculator validates that the wall thickness does not exceed half the outer side.

Which unit systems are supported?

Side lengths and wall thickness accept mm, cm, or inches. Length accepts mm, cm, m, inches, or feet. All values are converted to meters before the weight calculation runs.

What is weight per meter used for?

Weight per meter (kg/m) lets you quickly scale the result to any cut length without re-entering all values. Multiply kg/m by any additional length in meters to get total weight for bulk orders.

Iron Square Tube Weight Calculator

Name: Iron Square Tube Weight Calculator
Availability: InStock
Author: Nham Vu

Enter outer side length, wall thickness, and tube length to get the weight of an iron square hollow tube in kg and lb instantly.

Tube Dimensions

Outer Side Length

Wall Thickness

Length

Formula Reference

W = (A² − B²) × L × ρ

Where A = outer side (m), B = inner side = A − 2 × wall (m), L = length (m), ρ = 7874 kg/m³ (iron density), W = weight (kg).

Enter tube dimensions on the left and click Calculate.

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Summary

Enter outer side length, wall thickness, and tube length to get the weight of an iron square hollow tube in kg and lb instantly.

How it works

Enter the outer side length of the square tube and choose a unit (mm, cm, or in).
Enter the wall thickness and choose a unit (mm, cm, or in).
Enter the tube length and choose a unit (mm, cm, m, in, or ft).
Click Calculate — the inner side is derived automatically as Inner Side = Outer Side − 2 × Wall.
Weight is displayed in kilograms and pounds using an iron density of 7874 kg/m³.
A weight-per-meter figure is also shown to help with bulk length ordering.

Use cases

Estimating material weight for iron square tube framing and structural fabrication.
Calculating shipping and freight weight for square hollow section orders.
Preparing a bill of materials for procurement or purchasing departments.
Comparing wall thicknesses to balance structural rigidity against total weight.
Verifying crane and lifting load requirements before moving sections on site.
Quick field estimation of tube weight without manual calculation.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu