Density of Structural Steel
| Value | 7.85 g/cm³ (7,850 kg/m³) |
| Status | Typical value: varies by about ± 0.05 g/cm³ in practice |
| Source | FHWA, AASHTOWare Opis input sample for the FHWA LRFD Steel Bridge Design Example (FHWA web page, a US federal work): steel unit weight 0.490 kip/ft³, which is 7850 kg/m³ |
| Categories | Material PropertiesEngineering & Trade |
| Unit | Value |
|---|---|
| gram per cubic centimeter | 7.85 g/cm³ |
| kilogram per cubic meter | 7,850 kg/m³ |
| pound per cubic foot | 490.05949 lb/ft³ |
| kilogram per liter | 7.85 kg/L |
| pound per cubic yard | 13,231.606 lb/yd³ |
| gram per liter | 7,850 g/L |
| pound per imperial gallon | 78.675941 lb/imp gal |
| pound per US gallon | 65.511425 lb/gal |
8 more density units
| microgram per liter | 7,850,000,000 μg/L |
| milligram per cubic meter | 7,850,000,000 mg/m³ |
| milligram per liter | 7,850,000 mg/L |
| slug per cubic foot | 15.231515 slug/ft³ |
| gram per milliliter | 7.85 g/mL |
| tonne per cubic meter | 7.85 t/m³ |
| US short ton per cubic yard | 6.6158031 ton/yd³ |
| pound per cubic inch | 0.28359924 lb/in³ |
Learning zone
Steel is 97 % or more iron, and iron's density does not care whether the carbon content makes the alloy A36 or A992 or a quenched-and-tempered bolt. So 7850 kg/m³ (490 lb/ft³, 0.2836 lb/in³) covers essentially every carbon and low-alloy structural steel, and every shape table in the AISC manual is built on it. That is where the handy checks come from: a W-shape's weight in pounds per foot equals its area in square inches times 3.4, and steel plate weighs 40.8 lb/ft² per inch of thickness.
Watch two edges. Austenitic stainless (304, 316) is nearer 8000 kg/m³ because of the nickel and chromium, and cast iron is lighter at 7100–7300 kg/m³ because of the graphite flakes. The value drifts down with temperature, about 0.4 % by 500 °C, which matters for furnace work and never for a building. Use it for self-weight, shipping weight and thermal mass; use the mill certificate for anything you are certifying.
Cite this page
formula.expert. (2026, November 8). Density of Structural Steel. https://formula.expert/constants/density-structural-steel