OBJ ↔ STL Mesh Converter
Paste Wavefront OBJ or ASCII STL text, then convert it to OBJ, ASCII STL, or a saveable binary STL data URL. Scale vertices, swap Y-up/Z-up axes, and triangulate polygon faces locally in your browser.
About this tool
OBJ ↔ STL Mesh Converter converts simple triangle meshes between Wavefront
OBJ and STL directly in the browser. Paste OBJ text (v and f lines) or ASCII
STL text (solid / facet / vertex), choose the output format, and get a
copyable mesh result.
- OBJ to STL. OBJ vertices and faces are triangulated and emitted as ASCII
STL, or as a binary STL
data:model/stl;base64,...URL you can save. - STL to OBJ. ASCII STL facets are read as triangles and written as a clean
OBJ object with deduplicated vertices and
ftriangle faces. - Geometry options. Apply a uniform scale factor and optionally rotate between graphics-style Y-up coordinates and CAD/3D-print Z-up coordinates.
- Local conversion. The parser and writer run as WebAssembly in your browser; the pasted mesh is not uploaded.
Worked example
Paste this OBJ triangle, leave Convert to as STL, STL encoding as
ASCII STL, Scale factor as 1, Axis conversion as Keep axes, and
set Mesh name to triangle:
v 0 0 0
v 1 0 0
v 0 1 0
f 1 2 3
The output is:
solid triangle
facet normal 0 0 1
outer loop
vertex 0 0 0
vertex 1 0 0
vertex 0 1 0
endloop
endfacet
endsolid triangle
The normal is recomputed from the face winding. If you choose Binary STL data
URL, the output starts with data:model/stl;base64, and can be saved as an
.stl file.
FAQ
Can I upload a binary STL file?
No. This page takes pasted text, so it can read Wavefront OBJ text and ASCII STL text. Binary STL input is raw bytes and cannot be safely pasted into a textarea; re-export it as ASCII STL first, then convert it here. Binary STL is supported as an output via a saveable data URL.
What happens to OBJ materials, UVs, normals, and textures?
They are not preserved. STL stores only triangles, and this converter deliberately
reduces the mesh to triangle geometry. OBJ vt, vn, usemtl, mtllib, groups,
and texture references are ignored on input. STL facet normals are recomputed
from triangle winding when STL is written.
How are OBJ quads or polygons handled?
Faces with more than three vertices are fan-triangulated: f 1 2 3 4 becomes
triangles (1,2,3) and (1,3,4). Negative OBJ indices are supported. Curved
surfaces, NURBS, smoothing groups, and material assignments are not evaluated.
When should I use the Y-up/Z-up axis options?
Many graphics tools treat Y as the vertical axis, while CAD and 3D-printing workflows commonly treat Z as vertical. Choose Y-up → Z-up when moving a model from a graphics coordinate frame into a printing/CAD coordinate frame, and Z-up → Y-up for the reverse. Leave it on Keep axes if your coordinates are already correct.
Limits & notes
- Input must be text: Wavefront OBJ or ASCII STL. Binary STL input is not accepted.
- The converter preserves geometry only: no materials, textures, colors, smoothing groups, UVs, or custom metadata.
- OBJ polygon faces are triangulated with a simple fan, which is best for convex polygons. Non-planar or self-intersecting polygons may not triangulate the way a modeling package would.
- The binary STL option returns a base64 data URL rather than a raw byte preview;
save it with a
.stlextension if you need a file.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool mesh-convert "v 0 0 0
v 1 0 0
v 0 1 0
f 1 2 3"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/mesh-convert/?mesh=v%200%200%200%0Av%201%200%200%0Av%200%201%200%0Af%201%202%203&to=stl&stl_encoding=ascii&scale=1&axis=keep&name=meshMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.