OBJ to FBX.

Maintained by Bake3D · Updated 8 October 2026

Why turn an OBJ into an FBX

An OBJ model often comes as three kinds of files: the .obj with the shape, an .mtl with the materials, and the texture pictures. Move one of them and the model turns gray. FBX keeps all of it in one file, and it is the format Unity, Unreal Engine and Maya expect first. Unity’s own manual says to use FBX whenever possible (Unity model file formats).

This tool reads the OBJ with its MTL and pictures and writes one FBX. The colors, the material slots and the base color texture all go inside. Your files are read in your browser and never uploaded.

How to convert OBJ to FBX

1. Drop the .obj file on the box above, together with its .mtl and texture files. You can also drop the whole folder or a .zip. On a computer, Choose a folder picks a folder in one go.
2. Pick the units the OBJ was made in: metres, centimetres, millimetres or inches.
3. Pick the up axis: Y for most game and web models, Z for 3ds Max, CAD and 3D printing files.
4. Check the preview and the size in the report. A chair should be about 1 m tall, not 100 m or 1 cm.
5. Download the .fbx file.

Click Try a sample OBJ with MTL to see it work. The sample is the Bake3D fox as an .obj, an .mtl and a JPEG texture.

Pick the right units and up axis

An OBJ file is a list of points, and it never says what one unit is (OBJ format notes). The same file reads as 2 cm or 2 m depending on the app. That is why the tool asks you. It scales your choice to centimetres, the FBX default, and writes the unit inside the FBX, so apps that read it show the right size.

OBJ does not say which way is up either. If the preview shows your model on its back, switch the up axis to Z. The FBX is always written with Y up, like most FBX files.

Materials and textures

The MTL file names a color and a picture for each material. Each material becomes its own material slot in the FBX, with its color. The base color picture (map_Kd) is packed inside the FBX, so it travels with the model.

MTL files often name pictures with a folder, or with a full path from the computer they were made on. The tool looks for each picture next to the OBJ and the MTL first, then anywhere in what you added, by file name. If a picture is missing, the report names it. PNG and JPEG pictures go in as they are. TGA, BMP, GIF and WebP pictures are turned into PNG in your browser first.

Only the base color picture is kept. Bump, normal, shine and transparency maps (map_Bump, norm, map_Ks, map_d) are named in the report and left out, because the FBX writer only fills the color slot. Connect them again in your app if you need them.

What changes in the mesh

• Polygons become triangles. OBJ can store faces with four or more corners. The FBX stores triangles. Game engines split them anyway.
• Each object or group becomes a mesh. A model saved as o Body and o Hat gives two meshes.
• Shared corners are joined. Corners with the same point, normal and texture spot become one point again, so the mesh stays connected and the file stays small.
• Texture seams stay split. Where two faces share a point but use different spots on the texture, the point is stored twice, the way glTF and game engines store it. In Blender, Merge by Distance joins them if you want to edit the mesh.

What this converter does not do

OBJ has no skeleton and no animation, so the FBX has none either. The tool does not add a rig. It also does not repair holes, reduce triangles or change the shape.

If you need a character that moves, Bake3D can make one, but not from your OBJ. It makes a new textured model from a picture, then places the bones and animates it. See how image to 3D works, or play the free demo to see a finished character.

Open the FBX in your app

Unity. Drag the FBX into your Assets folder. Unity reads the unit in the file when Convert Units is on in the model’s import settings (Unity FBX import settings).

Unreal Engine. Import the FBX as a static mesh. Check the material slots after import, since each engine sets up materials its own way.

Blender. Use File, Import, FBX. Our free FBX viewer also opens the FBX in your browser so you can check it first.

If your app reads glTF, our OBJ to GLB converter makes a GLB instead. To look at the OBJ before you convert it, use the OBJ viewer.

How we checked it

Automated tests convert a 40 × 30 × 20 cm box corner saved with Z up, with its MTL in a materials folder and its texture in a textures folder that the MTL names as ../textures/paint.png. The FBX comes out 40 cm wide, 20 cm tall and 30 cm deep, with both materials, and the packed picture matches the PNG byte for byte. A bump map in the same MTL is named in the report. Other tests check an OBJ with no MTL and a file that is not an OBJ.

We opened the sample fox in Blender 4.4 after conversion. It had 41,822 points and 60,000 faces, the same as the original model, a 2048 × 2048 texture packed inside, and a size of 0.55 × 1.78 × 1.45 m. We have not yet opened these files in Unity or Unreal Engine ourselves.

Common questions

Why is my model 100 times too big or too small?

The units were set wrong. OBJ has no unit, so a file made in centimetres and read as metres comes out 100 times too big. Change OBJ units and watch the size in the report.

Why is my FBX gray?

The .mtl file or the pictures were not added. Drop the .obj together with its .mtl and textures, or drop the whole folder. The report lists any material or texture file it could not find.

Does the FBX keep quads?

No. Faces are split into triangles. The shape does not change, and game engines work in triangles anyway.

Can I add bones to the FBX here?

No. This tool changes the format only. To learn how a skeleton is added, read what rigging is.

Is my file uploaded?

No. The converter runs in your browser. The files are read, converted and saved on your computer.

Can I turn an FBX back into an OBJ?

Yes. Our free FBX to OBJ converter writes the shape of an FBX as OBJ.