OBJ vs FBX: what is the difference, and which should you use?

Which should I use, OBJ or FBX?

• A static prop, product model or 3D scan: OBJ. Almost every 3D program reads it, and it is easy to check in a text editor.
• A rigged or animated character: FBX. OBJ has no way to store bones, skin weights or keyframes.
• Unity or Unreal: FBX is the format both engines are built around. OBJ works for a static mesh.
• 3D printing: neither is ideal. Most slicers want STL or 3MF; OBJ is the next choice when you need colour. See STL vs OBJ.
• One file with the textures inside, for the web or AR: GLB. Our guide to 3D formats that keep textures compares GLB with FBX.

If nothing in the model moves, OBJ is the simpler, safer file. As soon as something has bones or keyframes, you need FBX (or glTF/GLB).

OBJ vs FBX at a glance

What an OBJ file holds

OBJ comes from Wavefront’s Advanced Visualizer animation software and is still one of the most widely read formats. The file is text: v lines for vertex positions, vt for UV coordinates, vn for normals and f for faces, which may have three, four or more corners. o and g lines split the model into named objects and groups, but there is no parent-child hierarchy.

Materials live outside the file. A mtllib line names the .mtl file, usemtl picks a material for the faces after it, and the .mtl names the images (for example map_Kd for the colour texture). The MTL material model is the classic diffuse, specular and ambient set; PBR values such as roughness and metalness are only unofficial extensions that some apps read.

OBJ has no animation, no bones, no units and no cameras or lights. For a deeper look at the OBJ layout, see STL vs OBJ.

What an FBX file holds

FBX started in 1996 as the native format of Kaydara’s Filmbox (later MotionBuilder). Alias bought Kaydara in 2004 and Autodesk bought Alias in 2006, so FBX is now Autodesk’s format. It was built to move whole scenes between programs, not only meshes.

• Meshes with UVs, normals and polygons, organised in a node hierarchy (parents, children and their transforms).
• Skeletons and skin weights, so a mesh deforms with its bones. Rigged characters (for example humanoid / standing characters with a skeleton) are usually moved between apps as FBX or glTF.
• Animation takes, blend shapes (morph targets), cameras and lights.
• Materials, plus textures either embedded in the file or referenced by a path.
• The scene’s unit and up axis, which is why the same FBX can arrive at a different scale in two programs that read those settings differently.

The catch is openness. Autodesk has never published an official spec. Its FBX SDK (C++ with Python bindings, for Windows, macOS, Linux and iOS) is free to download under Autodesk’s licence, and most commercial tools use it. Blender instead ships its own FBX importer and exporter, written without the SDK, so a few features can come through differently. FBX also has versions: a reader built for newer FBX 7 files may not open an old FBX 6 file until it is re-saved.

How textures travel in OBJ and FBX

This is where most “my model is grey” problems start.

• OBJ: the texture is never inside the .obj. You need the .obj, the .mtl and every image it names, with the paths in the .mtl still pointing to them. Send the .obj alone and the model opens untextured.
• FBX: it depends on export. With Embed Media turned on, the images are packed inside the FBX and importers unpack them; with it off, the FBX only stores paths, which break when the file moves to another computer.

In both formats, the material setup travels less well than the images. OBJ’s MTL has no standard PBR channels, and an FBX material often needs its maps reconnected in the engine. The 3D formats with textures guide explains embedded vs referenced textures in more detail, including GLB.

Which format each engine and tool prefers

What you lose when converting OBJ and FBX

• OBJ to FBX: geometry, UVs, normals, groups, MTL colours and the colour texture all carry over, and the images can be embedded so you move one file. Nothing is gained: the FBX has no rig or animation, because the OBJ never had one. OBJ stores no unit, so the converter has to assume one; check the scale after import. Our OBJ to FBX converter embeds the textures and lets you pick the scale.
• FBX to OBJ: the shape survives, but bones, skin weights, animation, blend shapes, cameras, lights and the hierarchy are dropped. An animated character is written in its rest pose. Materials shrink to basic MTL colours and a colour map, and embedded images have to be written out as separate files. Our FBX to OBJ converter extracts embedded textures and gives you the OBJ, MTL and images in one ZIP.

To keep animation in an open format, convert FBX to GLB instead with FBX to GLB: glTF can hold skeletons and animation clips.

Does converting lower the quality?

Not the mesh itself: vertex positions and UVs are copied as they are. What changes is the data around it. Expect to recheck smoothing (normals), scale and materials after any conversion.

Which file is bigger, OBJ or FBX?

For the same mesh, a binary FBX is usually smaller than an OBJ. OBJ writes every number as decimal text, while binary FBX stores raw numbers and can store large arrays deflate-compressed. An ASCII FBX loses most of that advantage.

Two things change the picture. An FBX exported with Embed Media includes its images, so it can be much bigger than the bare .obj; to compare fairly, add the OBJ’s .mtl and images too. And an FBX with animation carries keyframes that an OBJ never has. There is no fixed ratio: it depends on the mesh, the textures and the exporter.

Texture an OBJ or FBX model with AI

The AI 3D Texturing Studio opens OBJ and FBX files (and GLB, glTF, STL and PLY) up to 60 MB and 600,000 triangles, right in your browser. An OBJ is read on its own, without its .mtl, since the studio paints a new texture. An FBX is read as still meshes: animated (skinned) parts are textured in their rest pose.

You download one GLB with the texture inside. If your engine wants FBX, convert it with GLB to FBX. No model yet? Make one from a photo with image to 3D, then texture it here.

Questions