Convert STL to GLB
Free STL to GLB converter that runs in your browser. See real dimensions before you download.
Why convert STL to GLB?
People convert STL to GLB to show a printable model on a web page, in a viewer, on a phone or in AR. STL files are heavy for this use: they are uncompressed, have no materials and no unit, and browsers do not display them natively. GLB is a compact binary that web viewers, model-viewer and Three.js read directly. The STL's triangles are kept as they are and wrapped in a default grey material. Because STL numbers are millimetres and GLB is in metres, MeshShift divides by 1000 so a 50 mm part is 0.05 in the GLB and appears at the right size in AR. The up axis is rotated from Z-up to Y-up so the model stands upright.
How to convert STL to GLB
- Drop your STL file onto the converter — it opens in your browser, nothing is uploaded.
- Check the preview and the dimensions in mm; fix units or the up axis in “Units & orientation” if the size or orientation looks wrong.
- Choose GLB as the output and click Convert. Several files download as one ZIP.
What carries over from STL to GLB
| STL | GLB | Result | |
|---|---|---|---|
| Colour / materials | No | Yes | — |
| Textures | No | Yes | — |
| Units stored in file | No | Yes | Written as mm → metres |
| Separate parts | No | Yes | — |
| Usual up axis | Z | Y | Rotated (switchable) |
What changes
- A default grey material is added; STL has no colour to carry over.
- Millimetres become metres, so the real-world size is right in AR and web viewers.
- The model is rotated from Z-up to Y-up, the glTF convention.
- No textures or UVs are created.
Tips
- Large scanned STLs make heavy GLBs; reduce the triangle count if the file is for a website.
- Check the size in the viewer; AR placement shows the real object size.
- To add colours, use a 3D tool to paint or assign a material after conversion.
- Use the viewer's PLA, PETG or resin materials to preview how a print will look before you share it.
About STL files
STL was created by 3D Systems in the late 1980s for its stereolithography machines, and it became the default exchange format for 3D printing. A file describes a surface as a list of triangles, each with three vertices and a facet normal. That is all it contains. There is no header field for units, no colour, no texture and no notion of separate parts. Two flavours exist: ASCII, which is readable text but large, and binary, which spends exactly 50 bytes per triangle after an 80-byte header and a 4-byte triangle count. Binary is what almost every modern tool writes. Because the format is so small and so old, every slicer, CAD package and mesh editor can read it, which is why hobbyists still download most printable models as STL from sites like Printables and Thingiverse.
About GLB files
GLB is the binary container for glTF 2.0, the format the Khronos Group describes as the JPEG of 3D. One .glb file bundles a JSON scene description, binary mesh buffers and embedded images, so nothing can go missing in transit. The format was designed for efficient delivery and loading on the web, and it is now used by Three.js, Babylon.js, model-viewer, Google Search 3D results, Meta platforms, Unity and Unreal importers, and many marketplaces such as Sketchfab. glTF defines a physically based metallic-roughness material model, a node hierarchy, cameras, skins and animations. Coordinates are in metres with +Y up and a right-handed system. It is excellent for display and game assets, but it is a presentation format rather than a manufacturing one, so print workflows usually convert it first.
3D printing notes
STL is still the safest file to hand to a slicer. Bambu Studio, PrusaSlicer, OrcaSlicer, Cura and the resin tools Chitubox and Lychee all import it, and they all treat the numbers as millimetres. The usual problems are scale (a model exported from a metre-based tool arrives 1000 times too small) and meshes that are not watertight, which makes slicers fill or skip regions. MeshShift shows the real dimensions before you convert and can scale from metres automatically. Its print check lists holes, non-manifold edges and flipped normals, and one click rebuilds a closed solid at the same size. If you need colours or several plates in one file, use 3MF instead.
Frequently asked questions
Will the GLB have colours?
It gets a plain grey material, because an STL carries no colour data. You can recolour it in Blender or another editor, or assign colours in your web viewer's material settings.
Why is the GLB much smaller than the STL?
GLB is binary and typically stores shared vertices and indices, while many STLs repeat each vertex three times or are written in text. The shape is the same.
Is this STL to GLB converter free and private?
Yes. The conversion runs in your browser with JavaScript and WebAssembly, so your STL file is never uploaded to a server. There is no sign-up, no watermark and no daily limit; very large files are limited only by your device's memory.