How to convert OBJ to STEP
- Drop your .obj file into the box above, or click Choose file.
- Check the 3D preview, size and triangle count.
- Make sure STEP is selected as the output format. Adjust scale or up-axis if needed.
- Click Download. The .step file is created instantly on your device.
Why convert OBJ to STEP?
OBJ models from Blender, scanners and model libraries can be brought into SolidWorks, Fusion or FreeCAD as a STEP solid. Coplanar triangles are merged into single flat faces and quads are handled automatically, so the body is light and easy to select in CAD.
What changes in the conversion
- Triangles become clean faces. STEP is a CAD format, but a mesh has no parametric surfaces. Triangles on the same plane are merged into one face (with holes), curved areas stay faceted. The result is a solid you can measure, sketch on and combine – not a feature tree.
- Textures are dropped. STEP cannot store image textures (colours may be kept).
- Units. STEP is defined in metres. Large models (in millimetres) are scaled ×0.001 automatically so they appear at real size.
- Up-axis. OBJ is Y-up while STEP is usually Z-up; the model is rotated so it stands the right way up. Untick "Convert up-axis" to keep the raw coordinates.
- Geometry is preserved. Every triangle, with all object transforms applied, ends up in the new file.
OBJ vs STEP
| OBJ | STEP | |
|---|---|---|
| Full name | Wavefront OBJ | ISO 10303 (STEP AP203/AP214/AP242) |
| Stores | geometry, normals and UV coordinates (materials live in a separate .mtl file) | exact solids, assemblies and part names |
| Colour | No | Yes |
| Textures | Yes | No |
| Units | none | stored in the file (usually millimetres) |
| Exact CAD geometry | No | Yes |
About the formats
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.
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.
Frequently asked questions
Is this converter free?
Yes. You can convert OBJ to STEP for free – up to 5 CAD conversions a day, with no sign-up and no watermark. Pro gives you unlimited STEP conversions, batch conversion and every tool (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.