Round Bar Weight Calculator
Calculate the weight of a round bar or rod per unit length and in total, from diameter, length, and material density.
Enter your values
Bar diameter, length, and material.
How this calculator works
A round bar's cross-sectional area is a solid circle, so weight per unit length is:
D is bar diameter and ρ is material density. Multiply by total length for weight of one bar, then by quantity for a batch:
Common material densities
| Material | Density (kg/m³) |
|---|---|
| Mild / carbon steel | 7,850 |
| Stainless steel (304/316) | ~8,000 |
| Aluminum | ~2,700 |
| Copper | ~8,960 |
| Brass | ~8,730 |
Frequently asked questions
Does this work for hexagonal or square bar?
No — this uses the circular cross-section formula. For square bar, use W/L = side² × ρ; for hex bar, cross-sectional area is (3√3/2) × (across-flats/2)² — use the appropriate area formula for your bar's actual shape.
How accurate is this for mill-tolerance bar stock?
This calculates theoretical weight from nominal diameter. Actual mill stock can vary slightly within tolerance, so treat this as a close estimate rather than certified weight for invoicing purposes.