Convert DXF to STP in your application
3D InterOp is a CAD interoperability SDK that lets your software read DXF files and write STP, carrying across the exact geometry the DXF file contains.
Spatial does not offer an online converter or a desktop conversion app. 3D InterOp is a component that software vendors embed in their own products.
- Reads DXF · Writes STEP
- Mixed geometry → exact geometry
- C++ / C# APIs
DXF to STP at a glance
DXF can mix exact solids and facets; STEP stores exact geometry. Exact elements are written as exact geometry, and elements stored only as facets stay faceted.
| DXF (source) | STEP (target) | |
|---|---|---|
| Full name | Drawing Exchange Format | Standard for the Exchange of Product model data |
| Standard / owner | Autodesk | ISO 10303 — AP203, AP214, AP242 |
| File extensions | .dxf | .stp, .step |
| Geometry | 2D drawings and 3D data | Exact B-Rep |
| Assemblies / structure | Blocks and layers | Yes |
| PMI | None | Graphical and semantic (AP242) |
| 3D InterOp support | Read; write drawings only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from DXF to STEP.
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Preserved
Exact geometryExact B-Rep read from DXF is written to STP as exact geometry.
Why software vendors add DXF to STP conversion
Supplier and OEM exchange
STEP is the ISO standard most supply chains specify for exchanging 3D models. Writing it lets your users send data to partners on any CAD system.
Model-based definition
STEP AP242 can carry semantic PMI next to exact geometry, so your users can share models together with their manufacturing data.
Long-term archiving
As an ISO standard independent of any CAD vendor, STEP is widely used to archive product data.
Things to check before you ship
- Written STP versions: AP203, AP214 or AP242 (.stp, .step or .stpx).
- Supported DXF input: DXF/DWG 2.5 to 2027.
- A DXF file that only contains 2D drawings has no 3D geometry to write.
- Validate a sample of translated files in the target system your users actually work with.
Working with Spatial was a real milestone for us: Thanks to the powerful 3DInterOp library, we were able to successfully bring our complex CAD-based solutions to the cloud while remaining flexible to meet individual customer requirements. For us, Spatial is not just a technology partner, but a true enabler of our product strategy.
Dr. Arno Michelis, Founder, Simus Systems
Read the Case StudyAbout the formats
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Source format
What is a DXF (.dxf) file?
DXF is Autodesk’s documented exchange format for AutoCAD drawings, mostly stored as text. Many CAD, CAM and cutting tools import it to exchange 2D geometry.
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Target format
What is a STEP (.stp) file?
STEP is the ISO 10303 standard for exchanging 3D product data between CAD systems. Its application protocols range from exact geometry (AP203, AP214) to full model-based definition with PMI (AP242).
Frequently asked questions
The exact B-Rep that 3D InterOp reads from DXF is written to STP; parts stored only as facets stay faceted.
The STEP writer supports AP203, AP214 and AP242, with AP214 as the default. Your application sets the version at export; semantic PMI is written to AP242 only.
Then there is no 3D geometry to write to STP: 3D InterOp needs 3D content in the DXF file for this conversion.
Both the 2D content (drawing sheets) and the 3D data stored in the file.
No. 3D InterOp writes drawing sheets to DXF and DWG, but 3D export to these formats isn’t supported. To send 3D data back, write a neutral 3D format such as STEP.
3D InterOp reads DXF/DWG 2.5 to 2027.
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Building software that needs to convert DXF to STP?
3D InterOp is an SDK that lets your application read DXF and write STEP alongside 30+ CAD and BIM formats.