What is a STL file?
STL describes a 3D surface as nothing but a mesh of triangles. It carries no colour, texture, material or scene information, which is precisely why it has been the lingua franca of 3D printing since 1987: a slicer only needs the geometry.
At a glance
- Full name
- Stereolithography / Standard Tessellation Language
- Extensions
- .stl
- Type
- 3D model
- Introduced
- 1987
- Created by
- 3D Systems
- Compression
- None
- MIME type
- model/stl
Strengths
- Accepted by essentially every slicer and 3D printer
- Dead simple format, hard to get wrong
- Decades of tooling support
Limitations
- No colour, texture, material or animation data
- No units, so scale is ambiguous between applications
- Files get very large because vertices are repeated per triangle
When to use STL
Sending a model to a slicer or a 3D printer.
The model needs colour, textures or materials, or is destined for a web viewer or AR. Use GLB.
Convert STL files
Every tool below runs in your browser unless it is labelled otherwise, so the file stays on your device.
STL to GLB Converter
Converts STL 3D models to GLB (glTF binary) entirely in your browser, no upload or account needed, ready for web viewers, Unity, or Godot.
STL to OBJ Converter
Converts STL mesh files to Wavefront OBJ format, useful when an older modeling tool or export pipeline expects OBJ instead of STL.
GLB to STL Converter
Pulls mesh geometry out of GLB or glTF files and exports clean, printable STL, handy for slicing software and 3D printers.
STL compared
Related 3d model formats
Last updated 2026-08-03