Do I need to upload the .mtl file?

Yes, if you want materials. Put the .obj, the .mtl and the texture images in a ZIP and upload that — a bare .obj has no material information attached.

Why is the result a ZIP?

Because a glTF asset is several files that reference each other by relative path. GLBKit zips the .gltf, .bin and images together so the structure is preserved.

Is the glTF smaller or better looking than the OBJ?

It is structurally richer, not smaller. The materials become real PBR definitions, but since MTL has no metal/roughness values, the converted material is only as rich as the OBJ was.

OBJ to glTF Converter

Name: OBJ to glTF Converter
Author: GLBKit

Convert a Wavefront OBJ to a glTF JSON asset with a .bin buffer and separate images, for glTF tools and pipelines. Runs in your browser.

Drag & drop your OBJ file here

or click to browse

Supported Formats

.glb.gltf.obj.fbx.stl.ply.3mf.off.zip

Format Information

Source Format

OBJ.obj

OBJ (Wavefront)

The Wavefront OBJ format is a plain-text mesh description that has been the default interchange format for computer graphics since the 1990s. Geometry lives in the .obj file; colour and texture references live in a companion .mtl file.

What it carries: Vertex positions, normals, texture coordinates and polygon faces, plus what MTL can express: a diffuse colour, opacity, shininess and a single diffuse texture map. There are no PBR metal/roughness values, no normal maps, no vertex colours and no animation.

Open a OBJ file in the viewer

Target Format

glTF.gltf

glTF (JSON)

glTF 2.0 in its JSON form. The .gltf file is a readable text document that describes the scene and references an external .bin buffer plus separate image files, so a finished asset is a folder rather than a single file.

What it carries: The same scene data as GLB — PBR materials, image textures, node hierarchy, skinning, morph targets, keyframe animation, cameras and lights — but expressed as external file references instead of an embedded payload.

Open a glTF file in the viewer

About this conversion

This reads a Wavefront OBJ and writes the same scene as a glTF 2.0 JSON asset — a .gltf document with a .bin buffer and separate image files, delivered as a ZIP.

Why convert OBJ to glTF

Put an OBJ model through a glTF-based pipeline such as glTF Validator or a Draco/KTX2 optimisation step.
Store the asset unpacked so textures and the buffer can be replaced independently in version control.
Get the material definitions in a format that understands PBR, ready to be extended.

What happens during the conversion

Geometry

Positions, UVs, normals and faces are read from the OBJ and written as glTF meshes, keeping OBJ's group structure as glTF nodes. Faces are triangulated, so any polygon with more than three corners becomes triangles.

Materials and textures

The .mtl is read and mapped onto glTF PBR materials: diffuse colour to base colour, diffuse map to base-colour texture. Output images are written as separate files next to the .gltf, so the result is a folder, not a single asset.

Common use cases

Validating and optimising an OBJ asset with a glTF toolchain.
Migrating a repository from loose OBJ files to a structured scene format.
Preparing an asset for a renderer that wants a glTF material graph.

Limitations of this conversion

You need the .obj, .mtl and textures in one ZIP to keep materials; a bare .obj is geometry only.
MTL carries no PBR metal/roughness values, so the converted materials are incomplete by glTF standards.
Objects hidden in the OBJ scene are not written, because glTF output exports visible objects only.
The download is a ZIP. The .gltf, .bin and any images must stay at the same relative paths or the asset will not load.

How to convert OBJ to glTF

Three steps in the browser. Nothing is uploaded to a server, so an unwieldy file is limited only by your own device's memory.

STEP 1

Upload your OBJ package

Zip the .obj, .mtl and textures together if you want the material to come across.

STEP 2

Convert to glTF

The scene is written as a .gltf JSON document, a .bin buffer and the image files.

STEP 3

Unpack the ZIP and keep the files together

glTF relative paths must be preserved, so the .gltf, .bin and images belong in one folder.