GLB to STL converter — from glTF scene to printable mesh
Drop a GLB or glTF file below and get a clean, printable STL. The tool reads the geometry in your browser, rotates the model so it stands the right way up, scales it to the size you want in millimetres, and warns you about open edges before you slice. Nothing is uploaded — the whole conversion happens on your device.
What is a GLB file?
GLB is the binary form of glTF 2.0, the format the web and most 3D tools settled on for exchanging scenes. A single GLB bundles the mesh geometry, the node hierarchy, materials, textures and animations into one binary blob. That makes it great for viewing and for moving a model between apps, but it also means a GLB usually carries things a printer does not care about: cameras, lights, animation tracks, transparency and image textures. STL is the opposite — a bare list of triangles. Converting from GLB to STL is therefore a matter of keeping the geometry and throwing the rest away.
Y-up versus Z-up, and why your model is rotated
glTF defines Y as the up axis: a model standing upright in a GLB has its height along Y. Slicers, including Bambu Studio, PrusaSlicer and Cura, expect Z to be up. If you export straight from GLB to STL without touching the axes, the model arrives lying on its back. This tool rotates the geometry from Y-up to Z-up by default, which is the right choice for the large majority of GLB files. If your file was authored Z-up (some CAD exports and some game assets are), set Up axis to Z and the geometry passes through unchanged. Getting this wrong is the single most common reason a converted model looks tipped over, so it is worth a glance at the preview before you download.
Units and target size
glTF does not store real-world units: a coordinate of 1 could be one metre or one millimetre. STL is equally unit-blind, and slicers conventionally read STL numbers as millimetres. Rather than guess, this converter asks for a target size: the length of the model's largest dimension, in millimetres. Every other axis is scaled by the same factor, so the proportions never change. The default is 80 mm, which fits comfortably on every common build plate. A model that is 40 mm wide and 20 mm tall stays in that ratio; type 120 and it becomes 120 by 60. The preview and the size readout both use the scaled values, so what you see is what the STL will contain.
Why STL has no colour
The STL format predates multi-material printing and has no place to store colour, material or texture. Every triangle is geometry and nothing else. If your GLB has painted parts or a texture map, that information is dropped the moment you choose STL. For single-colour prints that is exactly what you want, and the file is as small and as compatible as possible. If the colour matters, use the GLB to 3MF converter, which keeps separate coloured parts for a multi-material printer.
Watertightness and mesh repair
A printable solid is watertight: every edge is shared by exactly two triangles, so the surface has no gaps and the slicer can tell inside from outside. GLB files from viewers and AI generators are not always watertight. They can contain single-sided planes, flipped normals, duplicate vertices or holes where two parts were meant to meet. The stats card counts open edges — edges that belong to only one triangle — and warns you when the count is above zero. A small number of open edges is often harmless, because slicers repair minor gaps automatically. A large number usually means the model has thin shells or stray triangles, and it is safer to run it through a repair pass before printing.
Where GLB files come from
People arrive at a GLB from many directions. Blender exports glTF 2.0 as GLB with a single menu command. Sketchfab lets you download models in glTF/GLB when the author has enabled downloads. AI mesh generators such as Meshy and Tripo hand you a GLB as their native output. Game engines and web viewers store GLB. Whatever the source, the geometry is what matters here: as long as you have the right to use the file, this tool will convert it. It only handles open formats, and it makes no claim about any other company's terms — that is between you and them.
What to check before you print
- Orientation. Look at the preview: the flat side should sit on the plate.
- Size. Confirm the millimetre readout matches your intent, not just the visual size.
- Walls. Anything thinner than about two nozzle widths will not print reliably.
- Open edges. If the warning appears, repair the mesh or enable the slicer's auto-repair.
Why is my model lying on its side after conversion?
GLB is usually Y-up while slicers expect Z-up. The tool rotates the model automatically, but if your file was authored Z-up, switch Up axis to Z.
Does the STL keep the colours from my GLB?
No. STL stores geometry only. If you need colour, export 3MF instead.
What size will the model be?
You set the target size as the largest dimension in millimetres; the other axes keep their proportions.
Is my GLB uploaded anywhere?
No. Parsing and STL writing run in your browser, so the file never leaves your device.
What does the open-edge warning mean?
It counts edges that belong to only one triangle. A watertight solid has none; if you see the warning, let your slicer repair the mesh before printing.
Which GLB files can I convert?
Binary GLB and glTF 2.0 with embedded geometry. Open formats only; proprietary or encrypted files are rejected with the library's own message.