Density of Structural Steel
| Value | 7850 kg/m³ |
| Status | Measured: ± 50 kg/m³ (0.0064 relative) |
| Source | AISC Steel Construction Manual, 15th ed. |
| Categories | Material PropertiesEngineering & Trademechanics |
| kilogram per cubic meter | 7,850 kg/m³ |
| gram per cubic centimeter | 7.85 g/cm³ |
| gram per milliliter | 7.85 g/mL |
| kilogram per liter | 7.85 kg/L |
| pound per cubic foot | 490.05949 lb/ft³ |
| pound per US gallon | 65.511425 lb/gal |
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.