How to Calculate Metal Weight: Formulas and Examples

How to Calculate Metal Weight

Accurate weight calculation is essential for material ordering, transportation planning, and structural analysis. This guide covers the formulas and methods for calculating metal weight.

Basic Formula

Weight = Volume × Density

For metals:

Steel density: 7,850 kg/m³
Aluminum density: 2,700 kg/m³
Copper density: 8,960 kg/m³
Stainless steel density: 8,000 kg/m³

Common Profile Calculations

Round Bar

Weight = π × (d/2)² × L × ρ

Square Bar

Weight = a² × L × ρ

Rectangular Tube

Weight = (2×(a×b) - 2×(a-2t)×(b-2t)) × L × ρ

Pipe

Weight = π × ((D/2)² - (d/2)²) × L × ρ

Where:

d, D = diameter
a, b = side dimensions
t = wall thickness
L = length
ρ = density

Practical Example

Calculate the weight of a 3-meter steel round bar with 50mm diameter:

Weight = π × (0.025)² × 3 × 7850

Weight = 3.14159 × 0.000625 × 3 × 7850

Weight ≈ 46.3 kg

Tips for Accuracy

Always use consistent units
Account for manufacturing tolerances
Add 5-10% for waste and cut losses
Verify density for specific alloys