Tool
Part weight calculator
Weight is the first number in a quote: it sets the material cost per piece and the freight per carton. Enter the blank dimensions and the material, and get kilograms.
Weight per piece
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Total weight
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Volume
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This is the blank weight from the drawing, not the finished part — machining removes material, but you buy the blank.
The formulas
| Shape | Volume (mm³) |
|---|---|
| Round bar | π × r² × L |
| Plate / block | W × T × L |
| Tube | π × (R² − r²) × L |
| Hex bar | 0.866 × AF² × L |
Then weight = volume (cm³) × density (g/cm³). AF is the across-flats dimension of the hex.
Densities we use
| Material | Density (g/cm³) |
|---|---|
| Aluminium 6061/7075 | 2.70 |
| Aluminium 2024 | 2.78 |
| Stainless 303/304 | 8.00 |
| Stainless 316 | 8.00 |
| Carbon steel | 7.85 |
| Alloy steel 4140 | 7.85 |
| Tool steel D2 | 7.70 |
| Brass H62 | 8.40 |
| Copper C110 | 8.94 |
| Bronze | 8.80 |
| Titanium TC4 | 4.43 |
| Zinc alloy Zamak 3 | 6.60 |
| POM (Acetal) | 1.41 |
| Nylon PA6 | 1.14 |
| ABS | 1.04 |
| Polycarbonate | 1.20 |
| PTFE | 2.20 |
| PEEK | 1.30 |
Questions
How do you calculate the weight of a machined part?
Volume × density. For round bar: π × r² × length. For plate: width × thickness × length. For tube: π × (outer radius² − inner radius²) × length. Multiply the volume in cm³ by the density in g/cm³ to get grams.
Why does part weight matter in a quote?
Because it sets the material cost and the freight. A part that weighs 300 g instead of 150 g doubles the bar stock per piece and can push the shipment into a different freight band.
Do you use theoretical or actual weight?
Theoretical, from the drawing, for quoting. The actual weight is lower because machining removes material — the weight here is the blank, not the finished part, which is what you pay for at the mill.
What density should I use for stainless?
8.0 g/cm³ for 303, 304 and 316, which is close enough for quoting. 316L is also 8.0. Only titanium (4.43) and aluminium (2.70) differ enough to matter.
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