STL vs OBJ
STL is the standard for 3D printing: it stores only triangles, with no colour, no units and no textures, which is all a slicer needs. OBJ also stores the shape but adds UV coordinates and basic materials in a companion .mtl file, so it suits rendering and texturing work too. For a single-colour print, STL is the safer, more universally accepted choice; for anything that will be painted, textured or edited, OBJ keeps more.
Side by side
| STL | OBJ | |
|---|---|---|
| Full name | stereolithography mesh | Wavefront OBJ |
| Created by | 3D Systems | Wavefront Technologies |
| Introduced | 1987 | late 1980s |
| Encoding | binary or ASCII | plain text, with a separate .mtl file |
| File size | compact in binary; repeats every shared vertex | large for dense meshes, because it's text |
| Materials | No | Yes |
| Textures | No | No |
| Animation | No | No |
| Colour | no colour or materials | basic materials in a separate .mtl file |
| Units | unitless (slicers assume millimetres) | unitless |
| Best for | 3D printing slicers | older 3D software and CAD-adjacent tools |
Choose STL when
- •You're sending a model to a slicer or a print service.
- •The model is a single-colour part and you only care about the shape.
- •You want the format every slicer and printer tool accepts.
Choose OBJ when
- •You need UV coordinates for texturing in another app.
- •You want basic material colours to survive the transfer.
- •You plan to keep editing the model in a 3D package.
Which apps open them
Of the 15 3D apps in our software guides, 9 open STL without conversion and 14 open OBJ. Only OBJ opens directly in Unity, Unreal Engine, Godot, Maya, Roblox Studio.
Questions
- Is STL better than OBJ?
- Neither is better everywhere. You're sending a model to a slicer or a print service: choose STL. You need UV coordinates for texturing in another app: choose OBJ.
- Can I convert STL to OBJ?
- Yes. Our STL to OBJ converter runs in your browser. The shape and supported materials carry over.
- Which file is smaller, STL or OBJ?
- STL: compact in binary; repeats every shared vertex. OBJ: large for dense meshes, because it's text. Actual size depends mostly on polygon count and texture resolution.
Written with AI assistance by the Renderlyst team in October 2026. Format support reflects each app's current release as we understand it, and we link the official documentation so you can confirm it for your version. Spotted something out of date? Email alishbakhalid766@gmail.com.