---
title: ".stl file — what it is and how to open it"
description: "A .stl file is a Stereolithography Model. The universal 3D printing format — a shell of triangles with no colour or units. How to open one on Windows, macOS and Linux, and what to convert it to."
url: https://atoneplace.net/file/stl/
site: "At One Place"
---

# .stl files

**.stl file: Stereolithography Model**

The universal 3D printing format — a shell of triangles with no colour or units.

## What opens a .stl file

- **Windows:** Ultimaker Cura, PrusaSlicer, Bambu Studio, Blender, MeshLab
- **macOS:** Ultimaker Cura, PrusaSlicer, Bambu Studio, Blender, MeshLab
- **Linux:** Ultimaker Cura, PrusaSlicer, Blender, FreeCAD
- **In a browser:** Autodesk Viewer

## What a .stl file is

STL came out of 3D Systems in 1987 and describes an object as a mesh of triangles. It carries no colour, materials or scale information, which is the classic cause of a model printing at the wrong size. Slicers such as Cura, PrusaSlicer and Bambu Studio open one and turn it into printer instructions; nothing on Windows or macOS previews an STL out of the box, so you install one of those or Blender to look at it.

## Converting it

A .stl file is commonly converted to .obj, .3mf, .gcode, .step or .fbx. It is a binary format, so a text editor will show unreadable characters rather than its contents.

## Details

- **Extension:** .stl
- **Full name:** Stereolithography Model
- **Category:** 3D and CAD
- **MIME type:** model/stl
- **Created by:** 3D Systems
- **Format:** Binary

## Common questions

### How do I open a .stl file?

On Windows use Ultimaker Cura; on macOS use Ultimaker Cura; on Linux use Ultimaker Cura. The universal 3D printing format — a shell of triangles with no colour or units.

### What is a .stl file?

Stereolithography Model. STL came out of 3D Systems in 1987 and describes an object as a mesh of triangles. It carries no colour, materials or scale information, which is the classic cause of a model printing at the wrong size.

### Can I convert a .stl file?

Yes. It is usually converted to .obj, .3mf, .gcode, .step or .fbx, either by exporting from one of the programs listed above or with a format converter.

## Related pages

- [.obj — Wavefront OBJ Model](https://atoneplace.net/file/obj/)
- [.fbx — Filmbox 3D Scene](https://atoneplace.net/file/fbx/)
- [.gcode — G-code Toolpath](https://atoneplace.net/file/gcode/)
- [.blend — Blender Project](https://atoneplace.net/file/blend/)
- [.3mf — 3D Manufacturing Format](https://atoneplace.net/file/3mf/)
- [.3ds — 3D Studio Model](https://atoneplace.net/file/3ds/)

## Sources

- Media Types Registry — IANA (https://www.iana.org/assignments/media-types/)
- Official vendor product documentation — At One Place (/about/)