STL Inspector FAQ
Measure an STL and estimate its print weight before you slice.
How do I find the volume of an STL file?
Open it in STL Inspector. It adds up the signed volume of a tetrahedron from the origin to every triangle, which gives the enclosed volume of a closed mesh, and shows it in cm³.
How much will my STL weigh when printed in PLA?
STL Inspector multiplies the volume by PLA's density of 1.24 g/cm³ for a solid print, and estimates a lighter weight at your infill percentage by treating about 0.8 mm of the surface as solid walls.
How can I tell if an STL has holes?
In a watertight mesh every edge is shared by exactly two triangles. STL Inspector counts the edges that are not and flags possible holes if it finds any.
Is my STL file uploaded?
No. The file is read in your browser. It is only uploaded if you tick “Keep the original file” when you save the report.
How accurate is the weight estimate?
It is a rough guide. It assumes about 0.8 mm of solid walls and skins, and your slicer's wall count, layer height, supports and brims will change the real figure. Use the slicer's number for final pricing.
Why does my model show as tiny?
STL files don't store units. This tool reads them as millimetres, like most slicers. If a model looks about 25 times too small, it was probably exported in inches.
Still have a question?
The STL Inspector guide walks through every setting.