Convert STEP to OBJ
Convert STEP to OBJ in your browser. The conversion runs on this page and the file never leaves your computer.
Result
Before you convert: what this keeps and what it destroys
Preserved
- The shape, to within the tessellation tolerance
- Overall dimensions and proportions
- Watertightness, where the input is watertight
- Separate parts and their positions
Destroyed
- Exact curves and surfaces, replaced by triangles
- Exact CAD surface data; the output has no native feature history
- A recorded unit: OBJ stores none
- Colour
- The transform hierarchy; object names and positions remain
- Texture images and texture coordinates, if present
↺ the reverse: OBJ → STEP · about .step · about .obj · just view it instead
Why people convert STEP to OBJ
A common route for getting a CAD part into a renderer, a game engine or a texturing tool, since everything reads OBJ.
Exact surfaces become triangles. The assembly structure survives as object names but not as a hierarchy, because OBJ has no transforms and positions are baked into the coordinates. The STEP's unit declaration is lost, since OBJ has no unit field. This site writes millimetre-magnitude numbers so the model at least matches what CAD tools expect.
What you get
You get a plain-text OBJ file you can open in an editor containing triangles. The reader tessellates supported surfaces or uses saved render meshes where required by the source format. Inspect curved faces at the intended output size. The triangle count depends on the model and the reader's meshing settings.
This conversion carries across object names, with positions applied to the geometry.
It does not carry across a recorded unit or colour.
The conversion runs in your browser. Your file stays on your computer and is not uploaded.
What to check afterwards
- STEP declares its unit in the file. Check the output dimensions in the receiving application, especially when its import settings can override the unit.
- The output keeps supported geometry and object names. The writer applies part transforms to the coordinates, without retaining the original transform hierarchy. It does not write material colours, texture coordinates or a companion material file.
- Curves become facets. STEP stores exact surfaces, so a hole is a cylinder with a radius. OBJ stores triangles, so that cylinder becomes a many-sided prism. Look at curved faces in the result at the size you intend to make the part.
If you need something this conversion cannot give you
If the unit has to be unambiguous, convert to 3MF instead. It records the unit in the file, so nobody downstream has to assume millimetres and nobody has to scale by 25.4 after the fact.
If you need editable CAD geometry, don't convert at all. Open the STEP file directly in FreeCAD, Fusion, Onshape or SolidWorks. Every mesh format destroys the exact surfaces, and no later conversion brings them back.
Going the other way
Convert OBJ back to STEP exists, but it is not the inverse of this page. Going this way tessellates exact surfaces into triangles. Going back rebuilds a faceted solid out of those triangles. You do not get your original surfaces back, and the round trip is lossy in a way that compounds.
How we know this conversion works
This pair was checked against 44 files from the test corpus on 2026-09-07. 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.