2026-02-28
STL vs OBJ vs GLB vs USDZ: Which 3D File Format Do You Actually Need?
A beginner-friendly breakdown of the 4 main 3D file formats. Learn when to use each one based on your project — 3D printing, game engines, AR, or editing in Blender.
Four download buttons, four cryptic file extensions. Here's which one you actually need.
Which Format Do You Need?
| If You Want To... | Download This |
|---|---|
| 3D print the model | STL |
| Edit in Blender, Maya, or other 3D software | OBJ |
| Use in a game engine (Unity, Unreal, Godot) | GLB |
| Display on a website or web app | GLB |
| View in AR on an iPhone or iPad | USDZ |
| Not sure / want maximum compatibility | GLB |
STL
The 3D printing standard. STL stores pure surface geometry (triangles, nothing else) which is exactly what slicers need. Every slicer reads it: Cura, PrusaSlicer, OrcaSlicer, Bambu Studio, all of them. No textures, no colors, no animations. If you're printing, this is the one.
OBJ
The universal interchange format, around since the 1980s. OBJ stores geometry plus optional texture coordinates and materials (via a companion .MTL file). Virtually every 3D application can import it, making it the safe choice when you need to move a model between different software packages for editing or retexturing.
GLB
The modern default. GLB packs geometry, PBR textures, materials, and animations into a single binary file, typically 2-5x smaller than an equivalent OBJ. It's supported by every major game engine, works natively in web viewers like Three.js and model-viewer, and is the right pick for Sketchfab, e-commerce previews, and social sharing. If you're only downloading one format and aren't sure what you need yet, go with GLB.
USDZ
Apple's AR format, based on Pixar's USD. Open a USDZ file on any iPhone or iPad and it drops the 3D model right into your camera view. Great for checking scale and proportions before printing, or for e-commerce "try in your space" features. It's Apple-only, though. Android uses GLB for AR instead.
Full Comparison
| Feature | STL | OBJ | GLB | USDZ |
|---|---|---|---|---|
| Geometry | Yes | Yes | Yes | Yes |
| Textures | No | Via .MTL | Built-in PBR | Built-in PBR |
| Animations | No | No | Yes | Limited |
| File Size | Large | Large | Compact | Compact |
| Single File | Yes | No (.mtl + .png) | Yes | Yes |
| Best For | 3D printing | Editing in 3D software | Web, games, sharing | AR on Apple devices |
Converting Between Formats
Model Spawner generates all four formats automatically, so you shouldn't need to convert. If you do, Blender (free) is the most reliable tool for the job. One thing to know: converting from STL to a textured format like GLB won't magically add textures. You'll just get a plain white surface. Always download the right format upfront when you can.