How to convert STEP to OBJ
- Drop your .step file into the box above, or click Choose file.
- Check the 3D preview, size and triangle count.
- Make sure OBJ is selected as the output format. Adjust scale or up-axis if needed.
- Click Download. The .obj file is created instantly on your device.
Why convert STEP to OBJ?
Converting STEP to OBJ turns a CAD part into a mesh for rendering in Blender, KeyShot or a game engine.
What changes in the conversion
- Surfaces become triangles. STEP stores exact curved surfaces; OBJ stores a triangle mesh. Curves are approximated with a fine tolerance.
- Colours are dropped. OBJ only stores geometry.
- Units. STEP is in metres; OBJ is usually read as millimetres. Small models are scaled ×1000 automatically – you can change this before downloading.
- Geometry is preserved. Every triangle, with all object transforms applied, ends up in the new file.
STEP vs OBJ
| STEP | OBJ | |
|---|---|---|
| Full name | ISO 10303 (STEP AP203/AP214/AP242) | Wavefront OBJ |
| Stores | exact solids, assemblies and part names | geometry, normals and UV coordinates (materials live in a separate .mtl file) |
| Colour | Yes | No |
| Textures | No | Yes |
| Units | stored in the file (usually millimetres) | none |
| Exact CAD geometry | Yes | No |
About the formats
STEP (ISO 10303 (STEP AP203/AP214/AP242)) was standardised as ISO 10303 for exchanging engineering data between CAD systems. It describes exact solid geometry (B-rep surfaces, edges and assemblies) rather than triangles. It is the neutral CAD format used by SolidWorks, Fusion 360, Inventor, CATIA, FreeCAD and Onshape.
OBJ (Wavefront OBJ) was introduced by Wavefront Technologies for its Advanced Visualizer software. It is a plain-text mesh format that stores vertices, faces, normals and texture coordinates, with materials in a separate MTL file. It is widely used to move models between 3D modelling programs such as Blender, Maya, 3ds Max and ZBrush.
Frequently asked questions
Is this converter free?
Yes. You can convert STEP to OBJ for free – up to 3 conversions a day, with no sign-up and no watermark. If you need more, Pro gives you unlimited conversions and batch conversion (free for 7 days).
Are my files uploaded to a server?
No. The conversion runs entirely in your browser using WebAssembly and JavaScript. Your model never leaves your computer, which also makes it safe for confidential parts and patient data.
Is there a file size limit?
There is no fixed limit. Files of a few hundred megabytes work on a typical laptop; the practical limit is your device's memory.