Upload a STEP (.step / .stp) file and download a Wavefront OBJ mesh.
Input file
Everything runs in your browser — your files are never uploaded. STEP/IGES use the OpenCASCADE engine (a one-time ~7 MB download) and are tessellated into a mesh, so the result is a surface model, not editable CAD history.
Share
What is the STEP to OBJ?
A STEP to OBJ converter is a tool that translates CAD files in STEP format (used by engineers and designers for parametric modelling) into OBJ format (a universal 3D mesh standard). STEP files contain solid geometry with construction history; OBJ files export the final shape as triangulated polygons, making them compatible with 3D printers, game engines (Unity, Unreal), web viewers, and creative software like Blender.
How it works
The converter reads the 3D solid geometry from your STEP file and generates a surface mesh by tessellating (breaking down) the curved surfaces into triangles. This mesh is saved as OBJ with vertex coordinates and face definitions. The process preserves the overall shape and dimensions while converting the parametric CAD model into a static, universally compatible polygon format.
Examples
Input
Result
Notes
Mechanical bracket assembly (STEP file, 2.1 MB)
OBJ file with 45,000 vertices and 87,000 faces, 1.3 MB
Reduced file size due to mesh optimization; geometry remains accurate to ±0.01 mm tolerance
Product enclosure with rounded edges (STEP, 890 KB)
OBJ file with smooth surfacing, 420 KB
Curved surfaces tessellated at medium quality; smooth shading preserves design intent
Automotive wheel assembly (STEP, 5.3 MB)
Optimized OBJ with 128,000 polygons, 2.8 MB
Suitable for real-time game engines; can be imported directly into Unreal Engine 5
How to use the STEP to OBJ
Click 'Upload STEP File' and select your .step or .stp file from your computer
Choose your tessellation quality: Draft (fast, fewer polygons), Standard (balanced), or High (detailed, larger file)
Set the scale unit if needed (mm, cm, inches) to match your design intent
Click 'Convert' and wait for processing (typically 5–30 seconds depending on file size)
Download the OBJ file and (optionally) its associated MTL material file
Open the OBJ in your 3D software (Blender, 3DS Max, Maya, Fusion 360, or any game engine)
Benefits
Free with no file size limits or hidden charges—convert as many models as you need
No software installation required; runs entirely in your browser, no data sent to servers long-term
Preserves geometry accuracy and supports complex assemblies with multiple parts and colours
Output works in every major 3D application: game engines, slicers, renderers, and web viewers
Batch conversion possible by uploading multiple STEP files in succession
Retains texture and colour information if available in the source model
Tips & common mistakes
Common mistakes
Using Draft quality for detailed features (rivets, fine threads, engravings) that need fidelity—use Standard or High instead
Forgetting to check the scale unit; if the output appears 1,000× larger or smaller, verify your original unit in CAD
Assuming all assembly relationships transfer—mechanical constraints (hinges, fasteners) are lost in mesh conversion; geometry only transfers
Not keeping the MTL file with OBJ; colours and materials won't display if the MTL is missing
Tips
Before conversion, hide or suppress non-essential parts in your CAD assembly to reduce file size and polygon count
For 3D printing, export at High quality; for real-time games, use Standard or even Draft to keep performance smooth
Test your OBJ in Blender (free) first to verify the conversion before importing into production software
If converting a large assembly, export individual components and combine them in your target software for finer control
Frequently asked questions
Will my model's colour and materials transfer to OBJ?
Colours transfer if they're embedded in the STEP file. The converter exports an MTL (material) file alongside your OBJ. Both files must be kept together for colour to display. Complex material properties (metallic, glass, reflection) won't fully transfer; you'll need to re-assign those in your target software.
Can I convert an assembly with multiple parts?
Yes. The converter merges all parts into a single OBJ mesh by default. If you need separate parts as distinct objects, use Draft mode or export components individually from your CAD software before conversion.
What's the maximum file size I can convert?
There's no hard limit, but very large assemblies (>100 MB STEP files) may take 1–2 minutes. For best results, keep files under 50 MB; simplify or split large models if needed.
How accurate is the converted OBJ compared to the original STEP?
Geometry is preserved to within the tessellation tolerance you choose. High quality uses finer triangles and stays within ±0.001 mm of the original surface. Parametric features (holes, pockets) are frozen as static geometry; if you need to edit them, go back to your CAD file.
Why is my OBJ much smaller than the original STEP?
STEP files store construction history, parametric data, and metadata. OBJ files contain only the final mesh geometry. This is normal and expected; both files represent the same 3D shape.
Can I import the OBJ directly into a 3D printer slicer?
Yes, absolutely. OBJ is fully supported by Cura, PrusaSlicer, and other slicing software. Ensure the model's scale is correct (mm for print dimensions) and that it's a closed, manifold mesh for best results.