Convert STEP to FBX Online
A STEP solid is tessellated by FreeCAD, passed through an intermediate GLB, and exported as FBX by Blender, so you get a single mesh object that Maya, 3ds Max, Unity and Unreal all import. Plan on fixing two things on import: the model arrives lying on its side, and its millimeter numbers are read as meters.
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Why convert STEP to FBX
FBX is the format game and animation pipelines expect, and STEP is the format mechanical engineering hands over. The two never meet directly: STEP stores exact trimmed surfaces for manufacturing, while Unity, Unreal, Maya and 3ds Max want polygons they can shade, bake and instance. If you have received a supplier's .step or .stp and need the part in a level, a cinematic or a product animation, something has to triangulate it first.
That is what happens here, in two steps on our servers. FreeCAD 1.1 reads the STEP shape through the OpenCASCADE 7.9 kernel and meshes it at a fixed 0.1 mm chord tolerance and 0.5 radian angular tolerance, writing a temporary GLB. Blender 5.1.2 then imports that GLB and exports FBX with its default axis and scale settings. Each of the two engine runs has its own ten-minute ceiling, so a heavy assembly has time to finish, but it is also why this pair takes a little longer than a direct mesh export.
Geometry is all that crosses. The FBX contains one mesh object with no materials, no UV map, no object names and no hierarchy, because STEP colors, part names and the assembly tree are not read by our importer. The data also stays Z up while FBX consumers expect Y up, so a 100 by 100 by 50 plate re-imports as 100 by 50 by 100, and Blender's exporter takes the millimeter numbers as meters, so a part modeled at 100 mm arrives 1000 times too large unless you rescale.
So this is a geometry bridge rather than a pipeline-ready asset. The people who use it are game and visualization artists blocking out real hardware, teams dropping a machine into a scene, and anyone who needs a CAD part in a tool that only reads FBX.
How to convert a STEP file to FBX
- Export one self-contained STEP from your CAD tool, in text Part 21 form. AP203, AP214 and AP242 all open; an assembly that only references outside part files has no geometry to convert.
- Keep the model as light as the scene needs. Because two engines run in sequence, a very dense STEP costs time twice, and fine detail becomes triangles you will have to live with.
- Upload the file here. Guest uploads are capped at 50 MB and 10 files per request, a free account allows 100 MB, Plus 200 MB and Pro 1 GB.
- Wait for both stages. Most files on this pair finished well under half a minute; large assemblies can take longer, and either stage stops at ten minutes.
- Download the .fbx within about four hours of completion.
- On import, set the up axis to Z or rotate 90 degrees about X, and apply a 0.001 scale factor if your engine works in meters, then assign materials and unwrap UVs.
What this converter does
- Two engines in one job: FreeCAD 1.1 with the OpenCASCADE 7.9 kernel reads the B-rep, and Blender 5.1.2 writes the FBX that Maya, 3ds Max, Unity and Unreal accept.
- No Autodesk or CAD license needed on your machine, and no add-on hunting for a STEP importer.
- Input repair before parsing: gzipped STEP is unpacked, UTF-16 recoded, a byte-order mark removed, and a missing END-ISO-10303-21 terminator added.
- Foreign files that merely carry a .step name, such as native SolidWorks or Inventor documents, are rejected before meshing rather than producing a broken result; the message shown is the generic "Could not read this 3D file" text.
- Units are normalized to millimeters on import, so a metre- or inch-tagged STEP is at least internally consistent before export.
- Empty results are filtered out at the intermediate stage: a GLB with no meshes fails the job, so a geometry-free STEP does not come back as a file.
Video Tutorial
Pro tip: convert STEP to FBX without installing anything! 💡 🔗 https://miconvert.com/en/step-to-fbx?utm_source=youtube&utm_medium=social&utm_campaign=step-to-fbx ⏱️ Timestamps: 0:00 Intro 0:06 Find
STEP to FBX questions
Why is my model enormous in Unity or Unreal?
The mesh numbers are millimeters, and Blender's FBX export treats them as meters, so a 120 mm bracket shows up as 120 meters. No unit conversion is applied anywhere in this chain. Set an import scale factor of 0.001 in your engine, or scale the object down by 0.001 in Blender, Maya or 3ds Max and apply the transform.
Why does the part arrive lying on its back?
CAD data is Z up and FBX consumers assume Y up, and we do not rotate anything. A plate that is 100 by 100 by 50 in CAD measures 100 by 50 by 100 after import. Choose Z up in your importer's axis settings if it has them, or rotate the object 90 degrees about X and apply the rotation.
Does the FBX keep colors, materials or part names?
No. The export produces one mesh object with no materials and no names, and STEP colors, product names and the assembly tree are never read on the way in. You will be assigning materials yourself, which is normal for a game or render pipeline anyway.
Are there UVs or textures in the result?
No UV map is generated and no textures are written, since a STEP file has none to give - unwrap in Blender, Maya or 3ds Max before texturing.
My conversion failed with "Could not read this 3D file". Why?
This is the most common failure on this pair and it happens before meshing. Typical causes are a truncated download, a binary or ZIP-wrapped file renamed to .step, a PDF or image with the wrong extension, or a native SolidWorks or Inventor document. Re-export AP214 text STEP from the original CAD file and re-upload.
Can I pick the mesh density or smooth the result?
No. Tessellation is fixed at 0.1 mm linear and 0.5 radian angular deviation, so you cannot trade triangles for accuracy here. If the facets are too visible or the count is too high, mesh the STEP in your CAD application at the deviation you want, or decimate and shade-smooth the FBX afterwards.
Should I use FBX or GLB for a game engine?
FBX is the safer pick for Maya, 3ds Max and older Unity and Unreal import paths. GLB from our STEP to GLB page skips the Blender stage, but it has the same Z up and unit mismatches, so either way you adjust rotation and scale once on import.
What happens to my files and how long is the download available?
Everything runs on our servers, not in your browser. The STEP you upload is deleted as soon as the job finishes its final attempt, and the FBX can be fetched from its random link for about four hours before it is deleted automatically. We do log file names, sizes and outcomes, and signed-in accounts keep a conversion history entry.