Weight from a STEP or STP model
A STEP model weight calculator does not read a mass property out of the CAD file. Most STEP exports store B-rep geometry, not a density. This page — also a STEP file weight calculator and STP file weight calculator — tessellates the solid, measures volume, then applies the same workshop densities as plate and bar: mild steel 7.85 g/cm³, stainless 8.00, aluminium 2.70, and the rest of the catalogue.
Formula
W = V_mesh × ρ
V from a closed triangle mesh · ρ in g/cm³
STEP model weight = CAD volume × density
STP mass uses the same mesh as STEP mass
Example — closed steel cube 100 mm
V = 0.100³ = 0.001 m³
W = 0.001 × 7850 = 7.85 kg
A real STEP of a filleted block will sit a little under that if the mesh undersamples the fillets.
STEP mass, STP volume and 3D CAD weight
After the model loads, pick an alloy to calculate weight from a STEP file — or calculate mass from a STEP file, which is the same number. Volume is shown next to mass, so the page also works as a STEP volume calculator, STP volume calculator and CAD volume calculator. For 3D CAD weight (a CAD model or 3D model weight calculator) the export must be a closed solid; open surfaces and construction geometry do not enclose a volume.
Densities on this page
- Mild Steel · 7.85 g/cm³
- Carbon Steel · 7.85 g/cm³
- Stainless Steel 304 · 8 g/cm³
- Stainless Steel 316 · 8 g/cm³
- EN8 · 7.85 g/cm³
- EN19 · 7.85 g/cm³
- EN24 · 7.85 g/cm³
- D2 · 7.7 g/cm³
- H13 · 7.8 g/cm³
- Aluminium · 2.7 g/cm³
- Aluminium 6061 · 2.7 g/cm³
- Aluminium 7075 · 2.81 g/cm³
- Copper · 8.96 g/cm³
- Brass · 8.5 g/cm³
- Bronze · 8.8 g/cm³
- Titanium · 4.51 g/cm³
- Cast Iron · 7.2 g/cm³
- Nylon · 1.14 g/cm³
- Delrin / Acetal · 1.41 g/cm³
- ABS · 1.04 g/cm³
- PVC · 1.38 g/cm³
How a toolroom uses STEP weight
Quotes often arrive as a STEP, not a cutting list. We open the solid, confirm it is the part we think it is, pick the alloy, and use the mass for a material take-off and a freight band. Click two points if a hole or span on the model does not match the email. Then we still weigh the stock on the shop floor before a certified shipping note.
Need plate, bar, tube or sheet instead of a CAD file? Use the material weight calculator. For a larger inspect-only canvas — a STEP file viewer with dimensions, no mass — open the STEP / STP viewer.