Glossary: Nominal Mass
**Nominal Mass** (or nominal unit weight) is the standardized weight of a structural component (such as reinforcing rebar, steel beams, or metal sheets) per unit length or unit area, established by regulatory codes for design and billing calculations, ignoring minor manufacturer rolling tolerances.
Rebar Nominal Weight Formula Derivation
In reinforcing steel bars, the nominal mass is used to translate linear dimensions (feet or meters) into shipping weights and billing invoices. Manufacturers roll rebar with ribs and deformities, causing minor weight variances, but calculations must rely on standardized nominal tables:
- US Standard (lb/ft): Governed by ASTM A615, nominal unit weights range from **0.376 lb/ft** (#3 bar) to **13.60 lb/ft** (#18 bar).
- Metric / ISO 6935-2 Standard (kg/m): Computed by the physics formula:
Mass (kg/m) = 0.006165 × d²
Where d is the nominal diameter in millimeters.