How the volume is calculated
For a closed mesh, the volume is computed exactly from the triangles using the divergence theorem (summing signed tetrahedra from the origin to each triangle). The result is only defined for watertight meshes – if the mesh has holes, the calculator tells you how many open edges were found.
From volume to weight
Weight = volume × density. The calculator assumes a fully solid part; for FDM prints with infill, use the 3D print cost calculator, which estimates the effect of infill.
Frequently asked questions
What units does it use?
STL files have no units; like slicers, the calculator reads them as millimetres. 1 cm³ = 1 ml = 1000 mm³.
Why is the volume "n/a"?
The mesh is not closed. Repair it (e.g. in your slicer or Meshmixer) so every edge is shared by two triangles.