Which is better for 3D printing, STL or OBJ?

STL, in practice. Both carry printable geometry and every major slicer reads both, but STL is single-file, compact in binary form, and immune to the missing-.mtl problem. Use OBJ for printing only when you need vertex colors for a full-color printer.

Does OBJ keep textures when converting from STL?

There are no textures to keep - STL cannot store UVs or materials, so a converted OBJ arrives untextured. The value of the conversion is getting a format you can then unwrap and texture in Blender or Maya.

Why does my OBJ open without any materials?

The .obj references a companion .mtl file plus texture images, and at least one of them didn't travel with it. Re-download or re-export with all files in one folder (or use a single-file format like GLB to avoid the problem entirely).

Is OBJ or STL smaller?

Binary STL is usually smaller than the same mesh as OBJ, since OBJ is plain text. But OBJ zips extremely well, and if the comparison includes textures, the images dwarf both geometry files anyway.

Can both formats hold multiple objects?

OBJ can - named groups keep parts separate and selectable. A standard STL is one anonymous mesh; multiple parts get welded into a single object on export.

STL vs OBJ: What's the Difference and Which Should You Use?

STL stores pure geometry - triangles and nothing else - which makes it the 3D printing standard. OBJ stores geometry plus UV coordinates, normals, and material references, which makes it the better exchange format for anything visual: texturing, rendering, game assets, and scans with color. If it's going to a printer, STL. If it's going to Blender, a renderer, or a texture pipeline, OBJ.

STL for printing, OBJ for visual work and DCC exchange.

Updated July 2026

.stl

STL (Stereolithography)

STL is the oldest and most universal 3D printing format. It describes a model as a plain list of triangles - nothing else. No colors, no materials, no units, no object names. That simplicity is exactly why every slicer, CAD tool, and print service on earth accepts it.

Since: 1987 - 3D Systems
Used by: Every slicer, CAD package, mesh-repair tool, and 3D-printing marketplace

.obj

OBJ (Wavefront Object)

OBJ is the plain-text workhorse of 3D interchange. It stores vertices, faces, UV coordinates, and normals in a human-readable file, with materials referenced from a companion .mtl file. Practically every 3D application of the last 30 years can read it.

Since: circa 1990 - Wavefront Technologies
Used by: Blender, Maya, 3ds Max, ZBrush, game engines, 3D scanners

STL vs OBJ: side by side

A check marks the stronger format for each dimension.

Dimension	STL	OBJ
Geometry	Triangles only	Polygons (quads and n-gons survive)
UV coordinates	None	Full UV mapping for textures
Colors & materials	None	Via companion .mtl file + texture images
Vertex colors (scans)	No	Yes (non-standard but widely supported)
3D printing pipeline	The universal slicer standard	Accepted by most slicers, but materials are ignored
Simplicity & robustness	Nearly impossible to parse wrong	Multi-file: the .mtl and textures get lost in transit
File size	Compact binary	Verbose text (but compresses well)

Which should you use?

Slicing for a 3D print

STL

Slicers want triangles; STL's binary form is compact and unambiguous.

Texturing or rendering a model

OBJ

UVs and material references survive - STL would arrive naked and unmappable.

Moving a photogrammetry scan with color

OBJ

Vertex colors and texture references carry the scan's appearance; STL strips both.

Archiving printable geometry

STL

One self-contained file, no sidecar .mtl or texture folder to lose.

One file vs a small family of files

The trap everyone falls into with OBJ: it is usually not one file. The .obj holds geometry and UVs, the .mtl defines materials, and the texture images live alongside both - and when any piece goes missing in an email or download, the model opens gray. STL has no such failure mode because it has nothing to lose: one file, geometry only, always complete. That difference explains most real-world format choices - OBJ when appearance matters and you control the hand-off, STL when robustness matters more than looks.

What each format actually stores

STL records flat triangles with optional face normals - no scale units, no color, no structure, not even object names. OBJ, a text format from 1990s Wavefront, records vertices, polygon faces (quads survive, which matters for re-editing), UV texture coordinates, vertex normals, named groups, and material assignments that point into the .mtl. Neither carries rigs, animations, or scene lighting - for that you're in FBX or GLB territory, which is a different comparison.

Converting between them

OBJ to STL is the everyday direction: triangulate, drop appearance data, print. It's lossless for shape and instant in the browser. STL to OBJ is geometrically trivial but cannot invent what STL never stored - the OBJ arrives with no UVs and no materials, ready to be unwrapped and textured in Blender. Both run free in our converter with no upload.

Convert between STL and OBJ - free

Both directions run locally in your browser. No upload, no signup, no watermark.

STL to OBJ converter OBJ to STL converter

STL vs OBJ - frequently asked questions

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