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
- Colour
- Separate parts and their positions
Destroyed
- Exact curves and surfaces, replaced by triangles
- The feature tree and any parametric history
- A recorded unit: OBJ stores none
↺ 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 exact surfaces in the STEP file are evaluated and tessellated at a tolerance fine enough that curves look smooth at normal viewing and printing sizes, The triangle count depends on how much curvature the part has: a bracket of flat faces produces very few, a turbine blade a great many.
Carried across: colour, the assembly structure.
Not carried across: a recorded unit. OBJ has nowhere to put it.
The whole conversion runs on this page, in your browser. Nothing is uploaded, so there is no server that could keep a copy of your file even in principle.
What to check afterwards
- STEP declares its unit in the file, so the physical size survives the conversion without anyone guessing. If the result is the wrong size, the problem came from somewhere other than this step.
- 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 2026-09-04. 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.