Convert STP to OBJ
Free STP to OBJ converter that runs in your browser. See real dimensions before you download.
How to convert STP to OBJ
- Drop your STP file onto the converter — it opens in your browser, nothing is uploaded.
- Check the preview and the dimensions in mm; fix units or the up axis in “Units & orientation” if the size or orientation looks wrong.
- Choose OBJ as the output and click Convert. Several files download as one ZIP.
What carries over from STP to OBJ
| STP | OBJ | Result | |
|---|---|---|---|
| Colour / materials | Yes | Yes | Kept |
| Textures | No | Yes | — |
| Units stored in file | Yes | No | Numbers in mm |
| Separate parts | Yes | Yes | Kept |
| Usual up axis | Z | Y | Rotated (switchable) |
About STP files
STEP, formally ISO 10303 and known as the Standard for the Exchange of Product model data, has been developed since the 1980s and is the main neutral format for moving CAD models between companies and systems. The usual application protocols are AP203 and AP214 for geometry and assemblies, and AP242 for modern product and manufacturing information. A .step or .stp file is plain text written in the EXPRESS-based Part 21 syntax. Unlike STL, it does not store triangles: it stores boundary representation (B-rep) geometry, meaning exact planes, cylinders, splines and NURBS surfaces joined by edges and faces into solids. That keeps holes perfectly round and dimensions precise, and allows the receiving CAD to keep editing faces. Files can contain assemblies, product structure, colours and units.
About OBJ files
OBJ comes from Wavefront Technologies' Advanced Visualizer software in the 1980s, and it has outlived the product. A file is plain text: lines starting with v define vertices, vt texture coordinates, vn normals, and f faces that reference those lists by index. Faces may be triangles, quads or larger polygons, and the g and o keywords group faces into named objects. Appearance is not in the OBJ at all; a line called mtllib points to a separate .mtl file that lists materials with diffuse colours and texture image names. The format is verbose, has no official unit and no scene hierarchy or animation, but it is trivial to read and write. That is why scanners, photogrammetry tools, sculpting programs and game pipelines still use it to move static meshes around.
3D printing notes
Most slicers cannot read STEP, though some, like PrusaSlicer, will import it and mesh it internally, so the usual step is exporting STL or 3MF from your CAD program. Tessellation quality decides how smooth the printed curves look: too coarse and cylinders become visible facets, too fine and files grow huge. MeshShift reads STEP and STP using OpenCascade in the browser and lets you pick draft, normal or fine tessellation. When it writes STEP, the result is a faceted B-rep: a solid made of flat triangular faces, not a parametric CAD model, so it will not give you editable holes or fillets. Use it to exchange a mesh as a solid, not to recover design intent.
Frequently asked questions
Is this STP to OBJ converter free and private?
Yes. The conversion runs in your browser with JavaScript and WebAssembly, so your STP file is never uploaded to a server. There is no sign-up, no watermark and no daily limit; very large files are limited only by your device's memory.
What is the difference between STEP and STP?
Nothing in the content. Both extensions hold the same ISO 10303 Part 21 text; .stp exists because older systems limited extensions to three letters. Any program that reads one reads the other, and renaming the file is enough.
Why does my OBJ import without its colours or textures?
The colour information is in a separate .mtl file and image files. If the MTL or textures are missing, renamed or in another folder, the importer shows plain grey geometry. Keep the OBJ, MTL and images together, or convert to GLB, which packs them in one file.