What does STL stand for?

STL stands for Stereolithography — the 3D-printing process 3D Systems invented in the 1980s. The file format was created to drive those early printers. There are several backronyms (Standard Tessellation Language, Standard Triangle Language) but the original name comes from the printing technology.

Binary, almost always. Binary STL is roughly 4x smaller and parses much faster. ASCII STL is human-readable but rarely useful — for debugging, use a mesh inspector like MeshLab instead of reading raw STL text. Fast3D exports binary STL by default.

Does STL store color?

No. Standard STL stores only triangle geometry — no colors, materials, textures, or UV coordinates. There is a VisCAM/Solidview extension that adds per-triangle color, but most software does not support it. For color 3D models, use 3MF (which Fast3D does not currently support) or paint the model inside your slicer.

Why is STL still the 3D-printing standard?

Compatibility. Every slicer reads STL reliably, every CAD package writes it, and its simplicity (just triangles) makes it virtually impossible to misinterpret. Newer formats like 3MF and AMF offer more features (color, materials, multiple parts) but STL's installed base is so large that it remains the default for years to come.

What makes a good STL for 3D printing?

Three things. First, manifold geometry — no holes, no flipped faces, no non-manifold edges. Second, reasonable triangle density — 0.5M-1M triangles is usually enough for visual quality; denser meshes slow the slicer without improving print quality. Third, correct scale — most slicers expect millimeters, so export in mm from your CAD tool or scale in the slicer.

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Supports GLB, GLTF, OBJ, STL, FBX, PLY

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Convert STL to other formats

Pick a target format to convert your STL files into.

GLB

STL → GLB

Binary glTF, the most common modern 3D format

GLTF

STL → GLTF

JSON-based glTF, human-readable

OBJ

STL → OBJ

Wavefront OBJ, widely supported geometry format

PLY

STL → PLY

Polygon File Format, common in 3D scanning

Convert other formats to STL

Convert from another 3D format into STL.

GLB

GLB → STL

Binary glTF, the most common modern 3D format

GLTF

GLTF → STL

JSON-based glTF, human-readable

OBJ

OBJ → STL

Wavefront OBJ, widely supported geometry format

FBX

FBX → STL

Autodesk FBX, popular in animation pipelines (input only)

PLY

PLY → STL

Polygon File Format, common in 3D scanning

What STL supports

Feature	STL
Geometry
Textures
Materials
Animation
Rigging

When to use STL

3D printing

STL is the universal input format for every 3D-printing slicer — Cura, PrusaSlicer, Bambu Studio, CHITUBOX. Use STL for guaranteed compatibility.

CAD mesh export

Solidworks, Fusion 360, Rhino, and Onshape all export STL. Use it to share mesh data with fabricators or service bureaus.

Mesh repair workflows

STL is the expected input for Meshmixer, Netfabb, Magics, and other mesh-repair tools. Run repair on STL before slicing.

Engineering and fabrication handoff

STL is the format service bureaus and rapid-prototyping shops expect. Send STL when a client asks for a 'printable file'.

Common STL workflows

Workflow 1

CAD → STL → slicer → print

Export STL from your CAD tool, drag into your slicer, configure supports and infill, slice to G-code, print. The standard 3D-printing pipeline.

Workflow 2

STL repair

Open the STL in Meshmixer or Windows 3D Builder, run auto-repair for non-manifold edges and holes, re-export. Repeat until the slicer reports no issues.

Workflow 3

STL → modern format conversion

Use Fast3D to convert STL to GLB for web display, OBJ for DCC editing, or PLY for scanning workflows.

STL software compatibility

Software	Support	Notes
3D printing slicers	Read	Universal support — Cura, PrusaSlicer, Bambu Studio, CHITUBOX, Lychee, and every other modern slicer.
CAD (Solidworks, Fusion 360, Rhino)	Read + Write	STL is the standard mesh export format from all major CAD tools.
Blender	Read + Write	Native STL import/export via the bundled STL add-on.
Mesh repair tools	Read + Write	Meshmixer, Netfabb, Magics, Windows 3D Builder all read and write STL natively.
Game engines	Limited	Unity and Unreal can import STL but it loses all material data. Use GLB for game engines.
Web browsers	None	Browsers do not load STL natively. Convert to GLB for web display.

About STL

STL is the de-facto standard for 3D printing and CAD interchange. It represents only the surface mesh as raw triangles — no textures, no materials, no animation. Its minimalism is its strength: every slicer and CAD package reads STL without configuration.

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