STL to GLB Converter
An STL is built for slicers; a GLB is built for screens. Convert a print file to GLB to show it on a shop page, in a portfolio or in AR, at its real size and standing the right way up.
3D Model Converter
or drop STL, OBJ, MTL … files here ·
Max 95 MB per file· Up to 20 files· Deleted after 30 minutes
Files are processed on our servers and deleted after 30 minutes.
STL and OBJ store no units. If a part shows up 10× or 25.4× too small or too big in the slicer, the units were read wrong — set them here.
Blender, CAD programs and slicers use Z-up; glTF, Unity and most game engines use Y-up. Switch it if the model lies on its side after import.
Used when converting STEP or IGES solids to a mesh. Fine gives smooth curves but larger files; coarse is enough for quick previews.
Only used for PNG, JPG or SVG input. Relief raises dark areas; a lithophane is a thin panel that shows the photo when lit from behind; extrude turns a logo or SVG outline into a flat solid shape.
Width of the printed model; the height follows the image's aspect ratio.
Maximum raised height for a relief or lithophane, or the thickness of an extruded shape. Lithophanes usually use 2–3 mm.
Solid plate under the relief so the print holds together. 0 means no base.
How to use this tool
- 1
Upload the STL
Add up to 20 binary or ASCII .stl files, up to 95 MB each. Several parts uploaded together each become their own GLB.
- 2
Check units and orientation
Model units is mm, which is what nearly every slicer and CAD export uses, and Up axis is Y-up for glTF. Change the units under Advanced settings if the STL was modeled in inches.
- 3
Convert to GLB
Press Convert to GLB and drag the result into a viewer to check it. Uploaded and converted files are deleted after 30 minutes.
The geometry of your print moves across untouched. What the converter adds is what STL never had: a scale in meters, a Y-up orientation, shared vertices, normals and a basic material, which is everything a web viewer needs to draw it.
What an STL file holds compared with a GLB
| STL | GLB | |
|---|---|---|
| Made for | 3D printing and slicers | Web, apps, AR viewers |
| Units | None stored; mm by convention | Meters, fixed by the spec |
| Up axis | Usually Z-up | Y-up |
| Vertices | Repeated for every triangle | Shared and indexed |
| Color and materials | None in the standard | PBR materials and textures |
| Multiple parts | Rare; usually one mesh | Nodes in a scene tree |
STL dates from 1987, when the Albert Consulting Group wrote it for 3D Systems' first stereolithography machines. A binary STL is an 80-byte header, a triangle count and then 50 bytes per triangle: a normal, three corners and two spare bytes. That is all a slicer needs to cut layers. It is a poor fit for a browser, though: there is no scale, no color, and every corner is written again for each triangle that shares it.
glTF 2.0, published by the Khronos Group in 2017, solves exactly that. It stores vertices once in binary buffers a graphics card can use directly, fixes the unit at one meter and the up axis at Y, and describes materials with physically based rendering. GLB is the single-file binary form of glTF, which is why model-viewer, three.js, Babylon.js, Shopify and Android's Scene Viewer all take it.
STL
STL mesh
STL (stereolithography) is a 3D mesh format created by 3D Systems in 1987. It describes only the surface geometry of an object as a list of triangles, without colour, materials, units or scene information. Its simplicity makes it the default input for 3D printing slicers such as Cura and PrusaSlicer. Curved surfaces are approximated by many flat triangles, so smooth models can produce very large files.
- Compression
- –
- Transparency
- –
- Animation
- No
- Introduced
- 1987 · 3D Systems
GLB
glTF Binary (GLB)
GLB is the binary form of glTF 2.0, the 3D transmission format published by the Khronos Group in 2017. It packs geometry, PBR materials, textures and animations into a single compact file designed for fast loading. GLB is widely used for web 3D, AR viewers, Android Scene Viewer and online model marketplaces. Some older desktop 3D tools and CAD programs do not import it.
- Compression
- –
- Transparency
- –
- Animation
- Yes
- Introduced
- 2017 · Khronos Group
Makers convert STL to GLB to display a printable part online or in AR, because browsers and 3D viewers expect a compact, scaled glTF file and know nothing of a slicer's unitless triangle list.
STL to GLB settings that matter
- Model units
- Tells the converter what one STL unit meant. Millimeters become 0.001 m, so a 120 mm figurine is 0.12 m tall in the GLB and appears at real size in AR.
- Up axis
- Slicers and CAD work Z-up while glTF is Y-up. Y-up rotates the part so it stands on the floor of the viewer instead of lying on its back.
- Merge into one mesh
- Off keeps separate solids as separate nodes you can hide or recolor later. On produces one object, handy for a single display piece.
- File encoding
- Does not apply here; GLB is always binary. Use the glTF option under Convert to if you need a readable JSON file.
Showing a 3D print online
Put the GLB on a page with Google's model-viewer web component and visitors can rotate the part, zoom in and, on Android, place it on their desk in AR.
Going the other direction, from a mesh to something you can edit with exact dimensions in Fusion 360 or SolidWorks, needs STL to STEP instead.
STL to GLB questions
Why is my converted GLB gray?
Standard STL stores triangles and nothing else: no colors, materials or textures. The GLB gets a plain neutral material so it renders with lighting. Add colors afterwards in Blender or the three.js editor, or start from an OBJ or 3MF with colors through OBJ to GLB.
Does the GLB print the same as the STL?
The geometry is the same triangles, rescaled into meters. Most slicers prefer STL or 3MF, though, so keep the original STL for printing and use the GLB for display only.
My printed part has several bodies. Can I keep them separate?
An STL usually stores all bodies as one triangle soup, so they arrive as one mesh. If the STL was exported as separate solids in ASCII format, each solid becomes its own node in the GLB as long as Merge into one mesh stays off.
How big will the GLB be compared with the STL?
Usually smaller than a binary STL. STL repeats every shared corner for each triangle it touches, while glTF stores each vertex once and refers to it by index. A typical binary STL shrinks noticeably; an ASCII STL shrinks far more.
Can a GLB from an STL be used for iPhone AR?
iPhones open USDZ rather than GLB in AR Quick Look. Convert the GLB once more with GLB to USDZ and use both files: GLB for Android and the web, USDZ for Apple devices.
Will curved surfaces look faceted in the viewer?
They can, because STL holds only flat triangles and no smoothing data. The converter calculates normals from the triangles; if the STL was exported coarse, re-export it at a finer resolution from your CAD program for a smoother look.
- OBJ to GLB ConverterConvert OBJ with its MTL and textures into a single GLB for three.js, model-viewer, Shopify and Android AR. Scale set to meters, materials embedded.
- glTF to GLB ConverterPack a .gltf file with its .bin buffers and texture images into a single GLB. Upload the folder as a ZIP; the model, materials and scale stay unchanged.
- GLB to USDZ ConverterConvert GLB models to USDZ so iPhone and iPad users can place them in AR from Safari, Messages or Files. PBR materials and textures carried across.
- STL to OBJ ConverterConvert STL to OBJ for Unity, texturing tools and other 3D apps that expect OBJ. Shared vertices, readable text and the same triangles, in seconds.
- STL to STEP ConverterConvert STL meshes to STEP files that open in Fusion 360, SolidWorks and FreeCAD. Set the units the STL never stored, then download a faceted STEP solid.
- GLB to FBX ConverterConvert GLB to FBX with meshes, textures, skeletons and animation for Unity, Unreal Engine, Maya or Blender pipelines that expect Autodesk FBX.