The free STL Weight, Centre of Mass & Moment of
Load an STL, OBJ, 3MF or STEP file and get exact volume, mass for any material, centre of mass, inertia tensor, principal moments and radii of gyration.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
What is the STL Weight, Centre of Mass & Moment of?
Knowing where a part balances matters for drones, rotating parts, robot arms, counterweights and anything you hang or spin. This tool reads a closed 3D model and computes its exact volume, mass in a chosen material, centre of mass and the full 3 × 3 inertia tensor, then diagonalises it to give the principal moments and axes. The centre of mass is marked with a red sphere in the viewer.
The maths is exact for the triangle mesh: the model is split into signed tetrahedra and their volume, first and second moments are summed, so there is no sampling error. Pick a material (PLA, PETG, aluminium, steel and more) or type a custom density, and the printed weight at a chosen infill percentage is estimated as well. Everything runs in your browser; the file is never uploaded.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Volume, mass, centroid and inertia tensor computed directly from the mesh.
Eigen-decomposition gives the principal moments, axes and radii of gyration.
Plastics, metals, wood and water, or a custom density.
Estimates shell plus infill weight for FDM prints.
AZRS tools are free to open and use.
It opens in your browser, so there is nothing to download.
Used for
Pick one to see how it fits.
How it compares
A plain look at this tool next to the usual alternative.
| This 3d tool | Desktop software | |
|---|---|---|
| Install | Nothing to install | Usually an app or program to install |
| Account | No signup | Depends on the product |
| Cost | Free to use | Free or paid, depends on the product |
| Where it runs | In your browser tab | On your computer |
Questions people ask
Is the centre of mass exact?
Yes for the mesh as given, assuming uniform density.
Are units millimetres?
Choose the file units and results are converted to mm, g and g·mm².
Does it handle several parts?
Multiple shells are treated as one solid with a shared centre of mass.
Is my file uploaded?
No — all processing happens in your browser.
How do I use the STL Weight, Centre of Mass & Moment of?
1. Drop in an STL, OBJ, 3MF or STEP file. 2. Set the file units and choose a material. 3. Read mass, centre of mass and inertia from the table. 4. Tick the marker box to see the centre of mass in the model.
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Exact volume, mass, centre of gravity and inertia tensor of any STL, OBJ, 3MF or STEP. Free to use.
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