# Convert OBJ to STL Online: Mesh to Mesh

Convert an OBJ triangle mesh to STL. Check scale and whether the mesh is closed; the result is not a CAD solid.

Convert OBJ to STL for a mesh workflow that expects STL. Verify units yourself. The conversion does not repair holes or create engineering geometry.

## Check the OBJ before converting

OBJ coordinates are treated as millimetres here, and textures or MTL libraries are not used. Confirm that the mesh is the model you intend to convert.

## Convert OBJ to STL

Choose STL and download the triangles. The file remains a mesh. It does not gain a unit declaration or a CAD feature history.

## Verify closure and scale

A known dimension confirms scale. Volume is approximate and only meaningful for a closed, consistent mesh. An open OBJ does not become a watertight solid because it was saved as STL.

## Questions

### Can I convert OBJ to STL online?

Yes. Upload an OBJ file, choose STL and download the mesh.

### Will the STL file be a closed solid?

Only if the OBJ mesh was already a closed, consistent shell. Conversion does not fill holes or rebuild CAD solids.

### How are OBJ units handled?

OBJ does not declare reliable units. CADProps assumes millimetres. Check one known dimension after conversion.

## Related guides

- [OBJ Mesh Units and Volume: Check Scale and a Closed Shell](https://www.cadprops.com/guides/obj-mesh-units-and-closure/index.md)
- [Do STL Files Have Units? How to Fix mm vs Inch Scale](https://www.cadprops.com/guides/stl-files-have-units/index.md)
- [STL Volume Zero or Missing? Check the Mesh Is Closed](https://www.cadprops.com/guides/why-stl-volume-is-zero/index.md)

## Related tools

- [OBJ viewer](https://www.cadprops.com/tools/obj-viewer/index.md)
- [STL viewer](https://www.cadprops.com/tools/stl-viewer/index.md)
- [STL to OBJ](https://www.cadprops.com/tools/stl-to-obj/index.md)

HTML page: https://www.cadprops.com/tools/obj-to-stl/