What the BREP keeps
- Exact solids and surfaces
- Faces, edges and vertices: the full boundary representation
- Every solid in its assembled position
- Coordinates in millimetres
Convert STEP or STP to BREP online
Upload a .step or .stp file and download an Open CASCADE BREP file with the exact geometry, ready for FreeCAD, CadQuery, gmsh or your own OCCT code. First 2 files free, any size up to 300 MB. After that, 1 credit per file.
STEP to BREP converter
Exact · Open CASCADESTEP
From STEP.step or .stp
BREP
exact · Open CASCADE
Sign in with Google or an emailed code to upload your own file. The sample file works without signing in.
Drop your STEP file here
or browse files
.step or .stp · up to 300 MBFirst 2 conversions free — any size up to 300 MB. Then $2.99 or 1 credit per file, charged at download. Prices include tax.
Have a BREP file? You can also turn BREP files into STEP.
- Files up to 300 MB
- Exact geometry, no triangles
- Native Open CASCADE format
STEP to BREP converter at a glance
- Converts
- STEP and STP (AP203, AP214, AP242) to BREP.
- You get
- One BREP file in Open CASCADE's native format: exact solids and surfaces, coordinates in millimetres. One shape, with no names or colours.
- File size
- Up to 300 MB. We email you when the file is ready.
- Price
- First 2 files free, any size up to 300 MB. After that, 1 credit per file.
How to convert STEP to BREP
STEP to BREP in four steps
To convert STEP or STP to BREP, sign in, upload your .step or .stp file above and download the BREP file. The geometry stays exact, with no triangles, and tools built on Open CASCADE load it without translating STEP again. STP to BREP works the same way.
Upload
Sign in, then drop a .step or .stp file up to 300 MB onto the converter.
Convert
The exact shape is written in Open CASCADE's native BREP format.
Download
We email you when the BREP is ready. Download one BREP file.
Load
Open it in FreeCAD, CadQuery or gmsh and check the shape.
STEP vs BREP
What changes when STEP becomes BREP
Both formats store exact geometry. BREP keeps only the shape.
What it leaves behind
- Part names and the assembly tree
- Colours
- PMI and product metadata
- The unit label (BREP has no unit field)
- Feature history, sketches and constraints
What a BREP file is for
Open CASCADE's own format
BREP is how Open CASCADE stores a shape, so OCCT-based tools load it directly.
BREPExact, not meshed
BREP stores the same boundary representation Open CASCADE builds when it reads your STEP: surfaces, edges and vertices, no triangles.
BREPNo units, millimetres inside
A BREP file has no unit field. Our STEP reader works in millimetres, so the coordinates are millimetres.
BREPOne shape
An assembly comes out as one compound shape with every part in place. Names, colours and the assembly tree stay in the STEP.
Most commercial CAD programs don't import Open CASCADE .brep files. To send the model to SolidWorks, Fusion or CATIA users, send the STEP. For meshing, gmsh opens .brep directly, so you can mesh the exact geometry for FEA.
Choose the right format
STEP vs BREP
Pick by what the next program needs.
| STEP | BREP | |
|---|---|---|
| Standard | ISO 10303 | Open CASCADE's native format |
| Geometry | Exact solids and surfaces | Exact solids and surfaces |
| Units | Stored | Not stored (ours is mm) |
| Names, colours and assembly tree | Yes | No |
| Opens in | Almost every CAD program | FreeCAD, CadQuery, gmsh, Salome and other OCCT tools |
| Best for | Exchange between CAD programs | Scripts, meshing and OCCT pipelines |
BREPConvert to BREP when
STEPKeep STEP whenThe model is going into FreeCAD, CadQuery, build123d, gmsh or your own Open CASCADE code.
You're in the right placeThe model is going to another CAD program or a supplier.
Open the STEP viewer IGESChoose IGES whenAn older CAD or CAM system asks for IGES.
STEP to IGES for CAMOpen it anywhere
Where BREP files open
Any tool built on Open CASCADE reads BREP.
FreeCADOpens BREP
CadQueryimportBrep
build123dimport_brep
gmshOpens BREP
SalomeImports BREP
OCCTBRepTools::Read
In Python, CadQuery's importBrep and build123d's import_brep load the file in one line. In C++, BRepTools::Read does the same.
FAQ
STEP to BREP questions
The format, units, CAD support, meshing, pricing and your files.
Contact usLast updated 6 November 2026What is a BREP file?
A .brep (or .brp) file is Open CASCADE's native format for a boundary representation: the exact surfaces, edges and vertices of a shape. FreeCAD, CadQuery, gmsh and other tools built on Open CASCADE read it.
How do I convert a STEP file to BREP?
Upload your .step or .stp file to the converter at the top of this page and download one BREP file with the exact geometry. FreeCAD, which is free, can also open a STEP and export BREP. Marathon OS is the paid route: first 2 files free, then 1 credit per file.
Is the Marathon OS STEP to BREP converter free?
First 2 files free, any size up to 300 MB. After that, 1 credit per file. Credit packs bring it down to $1.80 per file. Prices include tax, you pay only when you click Download and credits never expire.
Can I convert STP to BREP?
Yes. .stp is the short extension for STEP; both convert the same way.
Does STEP to BREP lose geometry?
No. Solids and surfaces stay exact; nothing is meshed. BREP drops what's around the geometry: part names, colours, the assembly tree and PMI.
What units does the BREP use?
BREP has no unit field. Our STEP reader works in millimetres, so the coordinates are millimetres.
Do I get a quality report?
Yes. Every conversion comes with a free quality report with 11 checks, including the number of solids and faces, whether the solids are closed and whether the volume matches the STEP.
Can SolidWorks or Fusion open a BREP file?
Most commercial CAD programs don't import Open CASCADE .brep files. Send them the STEP instead.
Can I mesh the BREP for FEA?
Yes. gmsh and Salome open .brep files directly, so you can mesh the exact geometry.
Is .brp the same as .brep?
Yes. Both extensions are used for the same Open CASCADE format.
Can I convert an assembly?
Yes. It comes out as one compound shape with every part in its assembled position, without names or the assembly tree.
Can I convert BREP back to STEP?
Yes. Our BREP to STEP conversion keeps the geometry exact.
Which STEP versions are supported?
STEP files from any CAD program that writes AP203, AP214 or AP242, as .step or .stp, up to 300 MB.
Do I need an account?
To upload your own file, sign in with Google or an emailed code. The sample file works without signing in.
How long does a STEP to BREP conversion take?
It depends on the part. Large assemblies can take a while, and we email you when the file is ready.
Are my STEP files private?
Uploads and downloads use HTTPS. Uploaded and converted files are deleted automatically after 7 days, and converted files aren't added to the public CAD library unless you publish them. You keep ownership of your design. See the Privacy Policy.
Convert your STEP file to BREP
An exact Open CASCADE BREP, ready for FreeCAD, CadQuery and gmsh. First 2 files free, any size up to 300 MB. After that, 1 credit per file.
Pricing
Pay as you go, cheaper by the pack
Your first 2 CAD file conversions are free, any size up to 300 MB, including the download. From conversion 3 on, each file costs 1 credit or a one-time payment, charged only when you click Download. 1 credit downloads any file up to 300 MB, and credits never expire.
Starter
3credits
$7.99
$2.66 each
3 downloads of any size. Good for a one-off project.
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.
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