FILE FORMAT GUIDE
What Is an FBX File?
Autodesk's proprietary 3D interchange format — one .fbx that can carry a mesh, a skeleton, clips, materials, cameras and lights between Maya, 3ds Max, Unity and Unreal.
A scene, not just a mesh
FBX is Autodesk's private 3D exchange format. Unlike STL (a triangle list) or OBJ (indexed geometry plus an optional MTL sidecar), an FBX is a scene graph. The same file can store mesh geometry, skeletal animation, blend shapes, materials, cameras, lights and the node hierarchy that ties them together. That is why game engines and animation pipelines treat it as the default hop between digital content creation (DCC) tools.
The extension is always .fbx. There are two encodings under that name: ASCII (a text dump of the node tree) and Binary (a compact packed form). Binary is what Maya, 3ds Max, Blender, Unity and Unreal write by default — smaller, faster, not human-readable. ASCII exists for debugging and a handful of older importers.
What is inside an FBX
| Data | Stored in FBX? |
|---|---|
| Mesh geometry | Yes — polygons with UVs and normals |
| Scene hierarchy / node transforms | Yes — the whole graph |
| Skeletal animation and skin weights | Yes — bones plus bind pose |
| Blend shapes / morph targets | Yes |
| Materials and textures | Yes — embedded or referenced |
| Cameras and lights | Yes |
| Animation clips and a timeline | Yes |
| Units | Not guaranteed — Maya often writes cm; engines vary |
| Print settings, supports, infill | No — use 3MF for that |
ASCII vs Binary
Both encodings describe the same objects. Binary FBX is the production file: a packed node stream that loaders parse quickly and that is typically several times smaller than the ASCII twin. ASCII FBX is a structured text document — you can open it in an editor, search for a node name, and sometimes hand-fix a broken path. The extension does not tell you which one you have; the file header does. If you are exchanging assets, send binary unless the other end asked for ASCII.
Where FBX came from
Kaydara built Filmbox in the 1990s as a motion-capture and character pipeline format. Autodesk acquired Kaydara in 2006 and folded FBX into Maya, 3ds Max and MotionBuilder as the native interchange between those apps — and, soon after, as the file Unity and Unreal expect on import. The format is still proprietary. Autodesk ships an SDK; Blender and three.js ship community loaders; there is no public ISO spec. That history is why FBX is everywhere in games and film, and why CAD, scanners and slicers still often do not speak it.
Where FBX files come from
| Source | What it exports |
|---|---|
| Maya / 3ds Max / MotionBuilder | Native interchange — mesh, rig, clips, materials |
| Blender | FBX export for engines; binary by default |
| Unity / Unreal Engine | Import path for characters and props; also re-export |
| Mixamo and mocap tools | Rigged characters with animation clips |
| 3D marketplaces (Turbosquid, CGTrader) | Download option alongside OBJ and glTF |
When to use FBX
- Game-engine import — Unity and Unreal both treat FBX as the standard inbound format.
- Animation pipelines that need a skeleton, skin weights, blend shapes and clips in one file.
- Cross-DCC exchange between Maya, 3ds Max, MotionBuilder and Blender.
- Marketplace assets that ship a rigged character rather than a static mesh.
The advantages are real: animation, bones and materials travel together, and the format is the industry default for that job. The costs are also real. FBX is proprietary; the spec is not public; versions do not always round-trip cleanly; files are larger than a geometry-only OBJ or a trimmed GLB. If the destination is a slicer, a scanner, or a tool that has never heard of Autodesk, pick something else.
FBX vs OBJ, glTF and DAE
OBJ is open and geometry-first: vertices, faces, UVs, no animation, no bones. glTF (usually a.glb) is the open, web-first scene format — PBR, skeleton, clips, one file. COLLADA (.dae) is an XML open standard that tried to be the universal scene exchange and ended up fragmented across exporters. FBX sits in the DCC/engine corner: richest Autodesk-world payload, least open.
| FBX | OBJ | glTF / GLB | DAE | |
|---|---|---|---|---|
| What it is | Autodesk scene container | Open indexed mesh | Khronos scene (web) | COLLADA XML scene |
| Open spec | No — proprietary | Yes | Yes (Khronos) | Yes (Khronos, fragmented) |
| Animation / bones | Yes | No | Yes | Yes (exporter-dependent) |
| Materials | Embedded or referenced | MTL sidecar | PBR in-file (GLB) | XML materials |
| Typical use | Maya/Max → Unity/Unreal | CAD, scans, static exchange | Web, AR, three.js | Legacy DCC exchange |
| File size | Often large | Verbose text | Compact binary (GLB) | Verbose XML |
Side-by-side with OBJ: OBJ vs FBX. To print an FBX, use FBX to STL. For a mesh every editor still opens, FBX to OBJ. For a webpage or AR preview, FBX to GLB. Conversion on this site runs in the browser; the file is not uploaded.
FAQ
Does FBX support animation?+
Yes. That is the main reason pipelines pick it over OBJ. An FBX can store skeletal animation, skin weights, blend shapes (morph targets), clips and a timeline. Unity, Unreal, Maya, 3ds Max and MotionBuilder all read that payload. Static formats such as OBJ and STL have nowhere to put a skeleton — converting FBX to either of those keeps the rest or bind pose as geometry and drops the clips.
What is the difference between ASCII and Binary FBX?+
Same scene graph, two encodings, both using the .fbx extension. Binary FBX is the default from Maya, 3ds Max, Blender, Unity and Unreal: smaller, faster to parse, not human-readable. ASCII FBX is a text dump of the same nodes — useful for debugging, version control diffs, or an older importer that only speaks the text form. If a tool offers both, pick binary unless you have a reason to inspect the file.
How do I open an FBX file?+
Maya, 3ds Max, MotionBuilder, Blender, Cinema 4D, Unity and Unreal Engine all import FBX natively. Windows 3D Viewer can preview many files. This site's FBX converters also parse .fbx in the browser (nothing uploaded) and write STL, OBJ or GLB. A text editor will not help on a binary FBX; only the ASCII variant is readable as text.
Can I 3D-print an FBX?+
Not directly. Slicers want STL or 3MF. Convert with the FBX to STL page on this site — materials, textures, bones and animation are dropped; geometry is kept in the rest or bind pose. If you need a specific frame, pose the character in Maya or Blender first, then export a still FBX and convert that.
FBX vs glTF — which should I use?+
FBX is Autodesk's proprietary interchange: native in Maya, 3ds Max, Unity and Unreal, rich animation and material graph, spec not public. glTF (usually shipped as a .glb) is an open Khronos standard built for the web, AR and three.js. Same kinds of payload — mesh, PBR, skeleton, clips — different audience. Use FBX inside a DCC/engine pipeline; use GLB on a webpage or in WebXR. Convert with FBX to GLB when the destination is a browser.
Is FBX an open format?+
No. Autodesk owns it. Kaydara created Filmbox in the 1990s; Autodesk bought the company in 2006. The SDK is available, community loaders exist (Blender, three.js), but there is no public ISO-style spec you implement from a one-page document. Version-to-version compatibility is imperfect — a 2020 ASCII file can surprise a 2014 importer. OBJ and glTF are the open alternatives.