Starter
3credits
$7.99
$2.66 each
3 downloads of any size. Good for a one-off project.
Free under 5 MBOBJ → STEPNo software installation
Convert OBJ to STEP online
Convert an OBJ (.obj) polygon mesh to STEP (.step or .stp) for CAD import, engineering review and supplier handoff. The result represents the OBJ geometry in a STEP-compatible form; it does not recreate parametric features, smooth analytic surfaces, materials, textures or the original design history.
Encrypted uploads Files up to 300 MB Automatically deleted within 7 days
Upload your OBJ file
Choose one OBJ file. This page is already configured to create STEP output.
Drag and drop your OBJ mesh here
or choose a file from your computer
Browse filesMaximum file size: 300 MB
Files under 5 MB convert and download free. Larger files use one credit for one completed download, regardless of file size.
No OBJ file available? Try a OBJ sample to see the conversion workflow.
Pricing
Pay as you go, cheaper by the pack
Files under 5 MB convert and download free. Larger files use one credit for one completed download, regardless of file size. 1 credit downloads any file, any size, and credits never expire.
Save 11%
Pro
5credits
$12.99
$2.60 each
5 downloads of any size. The everyday choice.
Team
10credits
$19.99
$2.00 each
10 downloads of any size. Best balance of price and volume.
Studio
15credits
$26.99
$1.80 each
15 downloads of any size. Lowest price per file.
No desktop software
Start the OBJ-to-STEP workflow in your browser without installing a CAD application or conversion plugin.
Geometry-first conversion
Move the visible polygon shape into a STEP workflow without claiming that mesh data becomes a native parametric CAD model.
Ready to inspect
Open the STEP result in the target CAD application and check scale, surface or body status, face count and whether separate OBJ objects were retained.
Open STEP viewerPrivate file handling
Conversion files stay private, are not added to the public CAD library and are automatically deleted within 7 days.
Continue your workflow
Inspect the OBJ, verify the STEP or request specialist help
Inspect the OBJ and its companion assets, validate the STEP geometry and request a native rebuild when editable engineering features are required.
Check the source OBJCheck mesh integrity, orientation, object groups and overall scale. Keep the .mtl and texture files as the visual source of truth.Open OBJ viewerInspect the STEP outputConfirm that the STEP contains the expected shape and opens as surfaces, shells or bodies suitable for the next workflow.Open STEP viewerNeed a parametric CAD model?Ask a CAD designer to rebuild sketches, dimensions, constraints and manufacturing features from the reference mesh.Hire a CAD designer
Simple conversion workflow
How to convert OBJ to STEP online
Move from a polygonal OBJ mesh to a STEP-compatible CAD exchange file in three steps.
Upload the OBJ file
Choose one .obj file up to 300 MB. Use a closed, manifold mesh with consistent normals for the most reliable geometric result.
Convert to STEP
The route is preconfigured for STEP output. Start the conversion without searching through a destination-format menu.
Download and verify
Open the .step or .stp result in the receiving CAD tool. Verify units, face count, body status, separate parts and critical dimensions.
Format behaviour
What actually happens when OBJ is converted to STEP?
OBJ stores polygon vertices, faces, normals, UV coordinates and optional object or group names; materials are usually referenced through a separate .mtl file and external textures. STEP is built for CAD exchange. Conversion translates the polygon geometry into a faceted STEP-compatible representation, but it cannot infer original sketches, features or smooth analytic surfaces.
What is normally retained
- Visible polygonal shape
- Vertex positions and face boundaries
- Model orientation
- Separate connected shells or objects where supported
- Closed volume only when the mesh is watertight and translated successfully
What is not retained or may change
- Materials defined in a companion MTL file
- Texture images and UV mapping
- Smoothing groups and rendering-specific normals
- Original sketches, constraints and feature history
- OBJ unit intent when it was not documented
Wavefront OBJOBJ
STEP modelSTEPFormat comparison
OBJ versus STEP
Choose the format according to what the next application needs—not because one is universally better.
| Feature | OBJ OBJ | STEP STEP |
|---|---|---|
| Primary use | 3D assets, rendering and polygon modelling | Neutral CAD exchange and engineering handoff |
| Geometry | Polygon mesh | B-rep or faceted geometry in a STEP container |
| Visual data | Can reference MTL materials, textures and UVs | Not designed to carry OBJ texture packages |
| Editability | Mesh and vertex editing | CAD operations may be possible, but no recovered parametric feature tree |
| Units and structure | No universal unit convention; objects and groups supported | Explicit units and product structure are possible, but depend on conversion support |
Choose STEP when
A CAD application or supplier specifically requires STEP
You need the visible mesh shape inside a CAD exchange workflow
Materials and textures are not required in the destination
A faceted, non-parametric result is acceptable
Keep OBJ when
The next step is rendering, animation or game-engine use
Textures, UVs, materials or smoothing information matter
You are still editing polygon topology
The receiving tool already accepts OBJ
Before continuing
Check the converted STEP before using it
A STEP file can open successfully while still being faceted, incorrectly scaled or missing visual and object data. Validate the engineering result.
- 01
Verify units and dimensions
OBJ has no universal unit convention. Measure a known feature and apply the intended scale in the STEP workflow.
- 02
Confirm surfaces, shells or solids
Check how the target CAD application classifies the converted geometry.
- 03
Inspect face count and performance
Dense OBJ meshes may create a heavy STEP with thousands of small faces.
- 04
Compare separate objects and groups
Confirm whether OBJ objects, groups or connected shells remained separate where required.
- 05
Check missing or reversed faces
Inspect normals, gaps, non-manifold edges and self-intersections inherited from the OBJ.
- 06
Keep visual assets separately
Retain the original OBJ, MTL and texture files because STEP normally will not preserve the rendered appearance.
Common problems
OBJ-to-STEP troubleshooting
Most issues are caused by mesh defects, undocumented units, dense topology or expecting rendering data and CAD features to survive the conversion.
The STEP looks faceted
Cause: The output follows the OBJ polygons.
Fix: Reduce unnecessary mesh density or request a native surface rebuild when smooth analytic faces are needed.Materials and textures disappeared
Cause: OBJ visual data lives in MTL and texture files that do not map to this STEP workflow.
Fix: Keep the original visual asset package and use STEP only for geometry exchange.The model is the wrong size
Cause: OBJ does not enforce a standard unit.
Fix: Confirm the authoring unit and rescale in the receiving CAD tool.The STEP is open surfaces, not a solid
Cause: The OBJ is not watertight or contains invalid topology.
Fix: Repair holes, non-manifold edges and self-intersections before retrying.The file is too large or slow
Cause: A high polygon count can generate thousands of STEP faces.
Fix: Decimate a copy while protecting critical dimensions.The STEP is hard to modify
Cause: Conversion did not create sketches, constraints or native features.
Fix: Commission a clean parametric rebuild for design changes.Secure processing
Your design files remain yours
Engineering files can contain confidential product geometry and documentation. Marathon OS keeps conversion uploads separate from its public CAD library and explains how each file is handled.
Encrypted transfer
Files are transferred over an encrypted connection.
Automatic deletion
Uploaded source files and converted outputs are automatically deleted within 7 days.
You retain ownership
Uploading or converting a file does not transfer ownership of the design to Marathon OS.
Never published automatically
Conversion files are not listed in the public Marathon OS CAD library.
Popular CAD conversion workflows
Explore a small set of adjacent engineering, mesh and drawing handoffs.
STEPSTL
STEP to STL
CAD to 3D-printing mesh
IGESSTEP
IGES to STEP
Legacy surfaces to modern CAD exchange
STLSTEP
STL to STEP
Mesh to CAD exchange
OBJSTL
OBJ to STL
Mesh handoff for slicing
3DMSTEP
3DM to STEP
Rhino to CAD/CAM exchange
DWGDXF
DWG to DXF
Drawing exchange
Marathon OS Design Hub
Find an existing model before rebuilding one
Search the Marathon OS library for a usable starting model. Review dimensions, licensing and manufacturing suitability before using a downloaded file.
3d-printing
Dragon Letter C | 3D Engineering Design File
STEP engineering modelFree
3d-printingPractice | 3D Engineering Design File
STEP engineering modelFree
3d-printingPractice 01 Basic Cad Experience | 3D Engineering Design File
STEP engineering modelFree
3d-printingCovid 19 Modular 140Mm X 140Mm Standard Smaller Sized 3D | Professional CAD Design
STEP engineering modelFree
3d-printingFissure V1 Step 1 | 3D CAD Engineering Model
STEP engineering modelFree
3d-printingGyroelongated Pentagonal Birotunda 1 | 3D CAD Engineering Model
STEP engineering modelFree
Frequently asked questions
Frequently asked questions about OBJ to STEP conversion
Clear answers about output behaviour, compatibility, pricing, file limits and privacy.
How do I convert OBJ to STEP online?
Upload the OBJ file (.obj), confirm STEP as the preselected output, start the conversion and download the STEP result (.step, .stp). Verify it in the application used for the next workflow.
Why convert OBJ to STEP?
Use OBJ-to-STEP when a CAD, manufacturing or supplier workflow requires STEP and only the polygonal OBJ geometry—not its rendered appearance—needs to be exchanged.
Does OBJ to STEP create an editable parametric model?
No. The STEP result is derived from the OBJ polygons. It does not recreate sketches, constraints, dimensions or native features, and it may remain a faceted shell or surface model.
Which OBJ and STEP extensions are supported?
This route accepts .obj input and creates .step, .stp output.
Is the OBJ to STEP converter free?
Files under 5 MB can be converted and downloaded free. Larger files use one credit for one completed download.
What is the maximum OBJ file size?
You can upload a OBJ file up to 300 MB. Dense meshes can produce large STEP files with many faces and slow CAD performance.
How are my files handled?
Files are transferred securely, are not published to the public CAD library and are automatically deleted within 7 days. You retain ownership of the uploaded design.