# glTF to STL Converter

> Turn a .gltf scene into a printable STL, converted from metres to millimetres and standing upright. Drop the .gltf with its .bin, or a .zip of the folder.

Page: https://printpal.io/convert/gltf-to-stl
Updated: 2026-11-12
Use it: open https://printpal.io/convert/gltf-to-stl in a browser and drop a file. Free, no account, files are processed locally and never uploaded.

A .gltf usually comes with a .bin buffer and texture images. Drop them together, or a .zip, and the converter assembles the scene, merges every mesh and writes an STL in millimetres, Z up. The textures aren't needed for STL, but the .bin is: it holds the geometry.

glTF's metres become millimetres, so a 0.2 m model prints 200 mm tall. Materials and animation are dropped. Check that the result is watertight before slicing; web models often have open edges and inside faces.

## How to convert glTF to STL

1. **Drop your glTF files.** Drop the .gltf together with its .bin and textures, or a .zip of the folder.
2. **Check the preview.** The model appears at the size and orientation it will have. Fix the file units, up axis or size under Size, units and orientation if needed.
3. **Choose STL options.** Binary STL by default (smallest, read everywhere). Tick ASCII only if an old tool asks for text STL.
4. **Convert and download.** One file downloads straight away. A batch gives a download per file and one .zip of all of them.

## What carries over

| | Result |
|---|---|
| Geometry | Every triangle is kept at full precision. |
| Color | Dropped: STL cannot store color. |
| Units | Converted from metres to millimetres, so it keeps its real size. A 0.05 m part comes out 50 mm. |
| Orientation | Turned from Y up to Z up, so it stands on the plate in a slicer. |
| Objects | Merged into one surface: STL has no objects. |
| Animation | Dropped: the model is written in its rest pose. |

## glTF at a glance (glTF 2.0 JSON)

A .gltf is the readable JSON form of glTF 2.0. The geometry usually sits in a separate .bin file and textures in image files, which makes it easy to inspect and edit, and easy to break by moving one file.

- **Stores:** A JSON scene that points at .bin buffers and image files (or embeds them)
- **Color:** Full: textures, base colors and vertex colors
- **Units:** Metres, fixed by the spec
- **Up axis:** Y, fixed by the spec
- **File size:** JSON plus buffers; embedded base64 adds about a third
- **Opens in:** Web viewers, Blender, three.js, Babylon.js, game engines

## STL at a glance (Stereolithography (Standard Triangle Language))

Created by 3D Systems in 1987 for the first stereolithography printers, STL is still the format every slicer and print service accepts. It describes a surface as a list of independent triangles, with no shared vertices, units, colors or scene structure.

- **Stores:** Loose triangles: three corners and a normal each, binary or ASCII
- **Color:** None in the standard
- **Units:** None written; slicers assume millimetres
- **Up axis:** Z, the slicer convention
- **File size:** 50 bytes per triangle in binary, about 5 times that as ASCII
- **Opens in:** Every slicer, CAD tool and 3D app

## Tips

- **Missing .bin?** The converter tells you which file the .gltf references. Drop it alongside.
- **Set the size** Use the height option in mm if the glTF's size is arbitrary.
- **Single file next time** GLB keeps everything in one file and converts the same way.

## FAQ

### Do I need the .bin file?

Yes, unless the .gltf has its data embedded. The .bin holds the vertices and triangles.

### Is the STL the right size?

It has the size the glTF declares, converted from metres to millimetres. Many web models aren't built to scale, so set a height if needed.

### Can I convert several glTF files at once?

Yes, drop each .gltf with its files, or zip each folder.

### Is the converter free? Are there limits?

Free, with no sign-up, watermark or file count limit. Batches and files of a few hundred MB work on most laptops; the only limit is your device's memory.

### Are my files uploaded?

No. Files are read and written by JavaScript and WebAssembly in your browser and never sent to PrintPal. The STEP and IGES reader is the only extra download, once, from a public CDN.

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