Steel Weight Calculator
Calculate the weight of steel plates, round bars, square bars, and tubes by entering dimensions in inches or millimeters.
Select a shape, enter dimensions, and get the steel weight in both metric and imperial.
Calculating Steel Weight by Dimensions
Steel weight is calculated by multiplying the volume of the shape by the density of steel. Mild steel (carbon steel) has a standard density of 7,850 kg/m3 (0.2836 lb/in3). Stainless steel is slightly denser at about 8,000 kg/m3 (0.2891 lb/in3). Knowing the weight of steel is essential for shipping cost estimates, structural load calculations, and material ordering.
Formulas by Shape:
Flat Plate / Sheet:
Weight = Length × Width × Thickness × Density
- In metric: dimensions in mm, result in kg:
(L × W × T) / 1,000,000 × 7.85 = kg per meter - In imperial: dimensions in inches:
L × W × T × 0.2836 = lbs
Round Bar (Solid Rod):
Weight = π × (Diameter/2)² × Length × Density
- In metric:
π × (D/2)² × L / 1,000,000 × 7.85 = kg - In imperial:
π × (D/2)² × L × 0.2836 = lbs
Square Bar:
Weight = Side × Side × Length × Density
- Same density factors as flat plate
Round Tube (Hollow Pipe):
Weight = π × ((OD/2)² - (ID/2)²) × Length × Density
Where OD = outer diameter and ID = inner diameter.
Alternatively, if you know the wall thickness: ID = OD - (2 × Wall Thickness)
Steel Density by Type:
| Steel Type | kg/m3 | lb/in3 |
|---|---|---|
| Mild / Carbon Steel | 7,850 | 0.2836 |
| Stainless 304 | 8,000 | 0.2891 |
| Stainless 316 | 7,990 | 0.2887 |
| Tool Steel | 7,720 | 0.2789 |
| Aluminum (for reference) | 2,710 | 0.0979 |
Quick Reference — Flat Plate Weight per Square Foot:
| Thickness | Weight (lb/ft2) | Weight (kg/m2) |
|---|---|---|
| 1/8" (3.2 mm) | 5.10 | 24.9 |
| 3/16" (4.8 mm) | 7.65 | 37.4 |
| 1/4" (6.4 mm) | 10.21 | 49.8 |
| 3/8" (9.5 mm) | 15.31 | 74.8 |
| 1/2" (12.7 mm) | 20.41 | 99.7 |
| 3/4" (19.1 mm) | 30.62 | 149.5 |
| 1" (25.4 mm) | 40.83 | 199.3 |
Practical Tips:
- Always add 5-10% waste factor when ordering material
- These calculations assume ideal geometry without cutouts or bevels
- For structural calculations, consult engineering tables that account for specific alloy properties