3D file converter: eight formats both ways and STEP for CAD
Drop a 3D model in one of eight formats, adjust the units and the mesh, and save it in another format, for example OBJ to STL. Everything runs in the browser, except the STEP export, which goes through the EduFacturing server.
Part of Pro, 15 EUR a month.
- 8 formatsin and out
- 4 unitsmm, cm, m and in
- Vertex weldinga cube's 36 vertices become 8
- STEP for CADonly STEP goes through a server
What a 3D file converter is and which formats it reads
The 3D file converter is an online tool from EduFacturing, part of Pro, that reads a 3D mesh in one of eight formats and writes it in another. The input and output formats are STL, OBJ, PLY, OFF, 3MF, GLB, AMF and DAE, and there is STEP for CAD as an output too.
Every format is read into one shared mesh of vertices and triangles. Before saving, you can change the units, scale and position, weld the vertices and flip the normals.
OBJ to STL, GLB to STL and more: formats, units, scale
Reads and writes eight formats
STL (binary and text), OBJ, PLY (binary and text), OFF, 3MF, GLB, AMF and DAE, all through the same mesh. The format is recognized by the extension, and by the content when the extension is unknown.
Changes units, scale and position
Millimeters, centimeters, meters and inches, a scale from 1 to 500%, and a position: as is, centered at the origin, or on the bed at Z = 0. A 3MF carries its own unit and the tool reads it for you.
Adjusts the mesh
It welds coincident vertices, removes degenerate triangles and flips the normals. It shows the open edges, the volume, the surface area and the size.
Makes STEP for CAD
Only this output leaves the browser: the mesh is uploaded to the EduFacturing server and comes back as STEP. Coplanar triangles are merged into flat faces.
When you need a converter: slicer, wrong scale, CAD
A file is rarely in the format the next program wants.
A file for the slicer
You get an OBJ, PLY or GLB and save it as STL or 3MF.
The wrong scale: inches instead of millimeters
A model drawn in inches and read as millimeters comes out 25.4 times smaller. Set the file unit and the target unit, and the size is fixed.
A model for CAD
A box or a bracket from an STL becomes a STEP solid with flat faces, to open in CAD.
Preparing a mesh
Weld the vertices so the mesh can be checked as closed, center the model on the bed and read its volume and size.
How a 3D file is converted and how the unit is changed
Every format is read into a shared mesh of vertices and triangles, and written from there in the chosen one. So there is no separate conversion for each pair of formats.
Reading
The unit of a 3MF (mm, cm, m or in) is taken as the unit of the file, and AMF and DAE are converted to millimeters on reading. STL, OBJ, PLY, OFF and GLB are bare numbers and are read as millimeters until you say otherwise.
Adjusting and checking
The order is: clean up, weld, flip normals, scale, center. An edge not shared by exactly two triangles is open; a mesh with no open edges and no degenerate triangles is closed, and only then is the volume right.
Writing
A 3MF records the output unit, and STEP is made from a binary STL uploaded to the server.
| Applies to | Formula | Meaning |
|---|---|---|
| Scale | k = (U_in / U_out) · (p / 100) | U is in mm: 1, 10, 1000 and 25.4 for mm, cm, m and in; p is the scale in percent |
| Volume | V = |Σ v₀·(v₁ × v₂)| / 6 | over the triangles, in the chosen unit cubed; right only for a closed mesh |
| STL size for STEP | B = 84 + 50·T | binary STL: 84 bytes plus 50 per triangle; measured against 200 MB |
What is different: the unit is a choice, STEP is honest
The unit is a choice, not a guess
A 3MF carries a unit and the tool reads it, while AMF and DAE are converted to millimeters. For STL and OBJ you pick the file unit, and the size is recalculated.
It is clear what leaves the browser
Only STEP is uploaded to the server, and before that the tool shows how many triangles and MB go. The screen says the result is a solid for CAD, not a parametric model.
Colors, textures and materials are dropped, because the mesh carries geometry only. 3MF, OBJ and AMF merge all objects into one mesh, while GLB reads the first mesh and DAE the first geometry. Only .glb is read, not text .gltf. AMF and DAE are always written in millimeters, so keep the target unit set to millimeters.
The tool does not fill holes or untangle intersecting faces: welding, cleanup and flipping normals are separate options, off by default. STEP does not recover curvature.
Questions about converting 3D files
How to convert OBJ to STL?
Drop the OBJ file, choose STL as the output and save. The same works for PLY, GLB, OFF, 3MF, AMF and DAE.
How to change units of an STL file?
Set the file unit and the target unit (mm, cm, m or in) and a scale from 1 to 500%. A model in inches, read as millimeters, comes out 25.4 times smaller.
What is a GLB file, and what can I convert it to?
A GLB is a 3D file; the tool reads .glb (not text .gltf), takes its first mesh, and saves it as STL, OBJ, 3MF or the other formats. Colors and textures are dropped.
Is my model uploaded to a server?
Not for STL, OBJ, PLY, OFF, 3MF, GLB, AMF and DAE: it all happens in your browser. Only the STEP export uploads the mesh to the EduFacturing server.
Why does my cube have 36 vertices instead of 8?
STL has no shared vertex list: 12 triangles times 3 is 36 vertices. Welding the coincident vertices brings it down to 8, and only then does the closed-mesh check work properly.
Can I get a STEP file for CAD, and what are the limits?
Yes, for boxy parts: coplanar triangles merge into flat faces, while curved surfaces stay as narrow strips. It needs a logged-in account, up to 10 conversions an hour and up to 200 MB for the binary STL.
How much does the 3D file converter cost?
It is part of Pro at 15 EUR a month. Pro also opens the other Pro tools in the catalog.
The 3D file converter is part of Pro
Pro costs 15 EUR a month and opens all 45 Pro tools.
In the Design group:
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Convert your model
Part of Pro, 15 EUR a month.