Convert OBJ to STEP through STL
There is no direct upload for OBJ to STEP. Convert the OBJ file to STL in your browser, then upload the STL to STL to STEP, which rebuilds it as a faceted solid.
Before you convert: what this keeps and what it destroys
Preserved
- The shape, as planar faces built from the triangles
- Overall dimensions and proportions
- Watertightness, where the input is watertight
- The unit, recorded in the file
- Supported colours present in the selected OBJ; external materials are not read
- Separate parts and their positions
Destroyed
- Cones, spheres, tori and NURBS, rebuilt as planar facets
- Texture images and texture coordinates, if present
↺ the reverse: STEP → OBJ · about .obj · about .step · just view it instead
Why people convert OBJ to STEP
Turning a downloaded or handed-over mesh into something CAD will accept, which is among the most common requests in this whole field.
What you get is a real B-rep solid. Coplanar triangles merge into single planar faces, so a cube that arrived as twelve triangles leaves as six faces, edges are shared, and a closed input produces a closed shell. It is genuinely useful as reference geometry to model around.
What you do not get is a parametric model, and no tool at any price can give you one, because the information was destroyed when the OBJ was written. Note also that OBJ carries no unit: the numbers are read as millimetres and the STEP declares millimetres on that basis, so a model authored in metres for a game engine will produce a confidently mislabelled file.
What you get
You get a plain-text STEP file you can open in an editor containing a boundary representation: planar faces, shared edges and, where the input was closed, a closed shell that CAD software will treat as a solid. Triangles that lay in the same plane are merged into single faces, so a flat side that arrived as two hundred triangles leaves as one face.
This conversion carries across the unit the file records, colour available in the selected OBJ (external materials are not read) and the supported part structure.
This page does not upload anything. The server converts STL to STEP only, and nothing else on this site leaves your computer.
What to check afterwards
- OBJ carries no unit. The numbers in the file are just numbers, so the conversion assumes millimetres. Check the overall dimensions of the result before you commit to machining or printing it. A file exported from a package set to inches will be 25.4 times out.
- This is a reconstruction, not a recovery. Coplanar triangles are merged into planar faces and the result is a real solid, but cones, spheres, tori and NURBS surfaces are not recovered and there is no feature tree. Use it as reference geometry.
If you need something this conversion cannot give you
If you need a parametric model, use the original CAD file or remodel the part using this output as reference. Surface fitting can create new geometry, but a mesh does not contain the original sketches or feature history.
Going the other way
Convert STEP back to OBJ is the reverse page. It is not the inverse of this one: reconstructing a solid from triangles produces faceted geometry, and tessellating it again would not return you to where you started.
How we know this conversion works
This pair was checked against 3 files from the test corpus on 2026-09-24. Each run parses its own output back in and compares the bounding box, the triangle count and, for closed solids, the volume against the input.
A pair that fails those checks doesn't get a page. That's why this site lists 120 conversions and not the several hundred a format-times-format grid would suggest.