AnyFormat

00 STL → GLB

STL to GLB

Indexed, scaled to metres, ready for a web viewer.

01STL in
02GLB out
03Options 2

glTF works in metres and the printing formats in millimetres. Leave this on unless your model comes out a thousand times the wrong size.

Multiplied on top of any unit conversion. Use 25.4 to turn inches into millimetres.

  • No upload The conversion runs in this tab. Your file never travels — not to us, and not to the advertising.
  • No sign-up, no email, no daily cap There is no account system to sign up to.
  • No size limit we invented Only your device's memory — about ~2 GB on a desktop browser, ~400 MB on a phone.
  • Turn your Wi-Fi off and convert anyway The conversion needs nothing but this page. Ads will not load without a connection; your file will still convert. That is the whole claim, and it takes five seconds to check.

Converts STL into GLB so the model works on the web. GLB is what <model-viewer>, Three.js, Babylon.js and AR quick-look all want, and STL is what CAD gave you.

Vertices are merged automatically

STL repeats every vertex once per triangle. Sending that to a browser wastes bandwidth and GPU memory in equal measure, so vertices are merged into an indexed mesh during the conversion — typically cutting the vertex count by around two thirds.

Indices are written as 16-bit where the mesh is small enough and 32-bit otherwise, which is what glTF expects and what keeps the file compact.

Scaled to metres

STL is almost always millimetres; glTF is metres. Without scaling, a 100 mm part appears 100 metres across in a viewer — filling the horizon rather than sitting on a table. The ×0.001 conversion is applied automatically, and can be turned off.

This matters most for AR, where the model is placed at real-world scale: get the units wrong and a phone case arrives the size of a building.

What is still missing

No material, because STL has none. Viewers will apply a default grey, which is usually fine for a mechanical part and disappointing for anything else. To add a material, open the GLB in Blender, assign one, and export again — or start from a format that had one.

Other names for this

Also searched as “stl to gltf”, “stl for model-viewer”, “stl to ar”.

Questions

How do I display the result on a web page?
The simplest route is Google’s <model-viewer> element: point its src at the .glb. Three.js and Babylon.js both load GLB directly too.
The model has no colour.
STL has no material information, so viewers apply a default. Add a material in Blender and re-export if you need one.
It appears enormous in the viewer.
Units. glTF is metres; a millimetre model is a thousand times too big without the automatic conversion, which is on by default.
Is my model uploaded?
No. The parsing and rewriting happen in this tab. Models are frequently confidential — an unreleased product, a client’s part, a scan of something proprietary — and none of it is transmitted. Turn your Wi-Fi off and the tool keeps working.
How large a model can I convert?
There is no imposed limit; the ceiling is your device’s memory. A desktop browser handles files of roughly 2 GB and a phone about 400 MB. A 200 MB STL — around four million triangles — converts in a few seconds on a laptop.