3D File Formats Explained: STL, OBJ, GLB, FBX, 3MF and STEP
There is no single best 3D format; the next step determines the right one. Inspect triangle geometry in the STL Viewer, open a print package with 3MF to STL, or use GLB to STL for a web scene with explicit loss warnings.
Compare formats by data and purpose
| Format | What it stores | Best suited to | Main limitation |
|---|---|---|---|
| STL | Triangle surface | Simple print-geometry exchange | No units, materials or scene structure |
| OBJ | Mesh, UVs, groups; materials through MTL | Static model and texturing exchange | Multiple linked files and no standard animation |
| GLB | Mesh, PBR materials, textures, scene and animation | Web, viewers, AR and asset delivery | No guaranteed print scale or printability |
| FBX | Scene, materials, skeleton and animation | DCC and animation interchange | Complex and excessive for print geometry |
| 3MF | Mesh, units, build items, materials and metadata | Additive-manufacturing project exchange | Extension support varies by application |
| STEP | Precise CAD surfaces and solids | Editable engineering master | Requires controlled tessellation before slicing |
Practical rule. Keep the editable master in its source CAD or DCC format, then create STL, 3MF or GLB as a derived delivery file for a defined next step.
Choose a format for the workflow
- For 3D printing, STEP works as an editable CAD master, 3MF as a unit-aware print project, and STL as minimal triangle exchange.
- For web and AR, GLB is often convenient because it packages scene, materials and textures into one binary asset.
- For rigs and animation, use a format that retains skeletons and clips, such as FBX or GLB; STL cannot carry them.
- For CNC, start from STEP or another CAD source when possible. G-code is already machine-, tool- and strategy-specific and is not a universal 3D model.
Free tools for inspection and conversion
Open STL or G-code locally, convert GLB or 3MF to STL, estimate a job with the cost calculator, or create STL from an image or 3D text. These tools do not upload your files to the server.
For an AIPRINTGEN export, check which format the model downloads in and the focused STL, OBJ and GLB comparison. To create a new source model, open the 3D model generator.
Frequently asked questions about 3D formats
Which is better for 3D printing, STL or 3MF?
STL is simple and widely supported, while 3MF can preserve units, multiple objects, materials and project data. The best choice depends on the software and printer chain.
Can GLB be converted to STL without loss?
No. Triangle geometry and transforms can transfer, but STL cannot store PBR materials, textures, UVs, animation, rigs or scene hierarchy.
Why keep STEP as a master file?
STEP represents precise CAD surfaces and solids. Once tessellated into a mesh, accuracy depends on export settings and the original parametric structure is normally lost.
Is G-code a 3D model format?
No. It is a set of motion and equipment commands prepared for a specific manufacturing process, machine or printer.
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