How it works
The weight of any uniform bar or plate is its volume times the density of the metal. Volume is the cross-section area times the length; the area depends on the shape: width × thickness for plate and flat bar, π/4 × diameter² for round bar, and side² for square bar.
Weights here are theoretical, from nominal dimensions. Mill tolerances, rolled edges, and alloy variation mean a real piece can differ by a few percent, so use the mill certificate or scale weight when it matters, such as for lifting or shipping.
Worked example
A 48 in × 24 in × 1/4 in carbon steel plate:
- Density of carbon steel = 7,850 kg/m³ × 0.000036127 = 0.2836 lb/in³
- Area = 24 in × 0.25 in = 6 in²
- One piece = 6 in² × 48 in × 0.2836 lb/in³ = 81.68 lb
- Total weight = 81.68 lb × 1 = 81.7 lb
| Input | Value |
|---|---|
| Material | Carbon steel |
| Shape | Plate or flat bar |
| Length | 48 in |
| Width (or diameter, or side) | 24 in |
| Thickness (plate and flat bar only) | 0.25 in |
| Number of pieces | 1 |
| Result | Value |
|---|---|
| Total weight | 81.7 lb |
| Weight of one piece | 81.68 lb |
| Weight per foot of length | 20.42 lb/ft |
| Cross-section area | 6 in² |
Densities used
| Material | kg/m³ | lb/in³ | lb per ft² per in thick |
|---|---|---|---|
| Carbon steel | 7,850 | 0.2836 | 40.8 |
| Stainless steel (about 8.0 g/cm³) | 8,000 | 0.2890 | 41.6 |
| Aluminum 6061 | 2,720 | 0.0983 | 14.2 |
| Copper | 8,940 | 0.3230 | 46.5 |
| Brass (60/40) | 8,520 | 0.3078 | 44.3 |
Show the densities used table
| Material | kg/m³ | lb/in³ | lb per ft² per in thick |
|---|---|---|---|
| Carbon steel | 7,850 | 0.2836 | 40.8 |
| Stainless steel (about 8.0 g/cm³) | 8,000 | 0.2890 | 41.6 |
| Aluminum 6061 | 2,720 | 0.0983 | 14.2 |
| Copper | 8,940 | 0.3230 | 46.5 |
| Brass (60/40) | 8,520 | 0.3078 | 44.3 |
Actual density varies a little by alloy and supplier.
Assumptions and limits
- Uses nominal dimensions and one density per material. Real bars and plates vary slightly with alloy and tolerance.
- Stainless steel density spans roughly 7.5 to 8.0 g/cm³ by grade; the 8.0 value is at the heavy end, so a lighter grade weighs a little less.
- Does not include coatings, holes, cutouts, or corner radii; subtract those volumes if they matter.
Common questions
How much does a steel plate weigh per square foot?
Carbon steel weighs about 40.8 lb per square foot for each inch of thickness, so a 1/4 in plate is about 10.2 lb per square foot.
How do I find the weight of round bar?
Use π/4 × diameter² for the area, multiply by the length, then by the density of the metal.
Is the answer exact?
It is a theoretical weight from nominal dimensions. Mill tolerances and alloy differences mean a real piece can differ by a few percent.
Can I use it for lifting or rigging?
Use it as a planning estimate only. Weigh the piece or use the mill certificate when the load matters.
Sources
- Densities from the Engineering ToolBox metals and alloys table (carbon steel 7,850 kg/m³; aluminum 6061 2,720; copper 8,940; brass 8,520; stainless steel 7,480 to 8,000).
- Weight = volume × density; 1 kg/m³ = 0.000036127 lb/in³.
- Read them: Engineering ToolBox: metals and alloys densities
Updated 2026-09-30