OBJ to glTF: How to Convert (and What Gets Lost)

OBJ is a plain-text geometry format that has barely changed since the early 1990s. It stores vertices, faces, vertex normals, and texture coordinates, with materials kept in an accompanying .mtl file. It is human-readable, easy to parse, and supported essentially everywhere — which is why it remains the most common interchange format between modeling tools.

• Plain-text format, line-based and trivially diffable
• Materials live in a separate .mtl file alongside the .obj
• Supports vertex colors, UVs, normals, and named groups
• No animation, no rigging, no scene hierarchy

glTF is the JSON-based form of the same format that GLB packages as a single binary. A .gltf file describes the scene as readable JSON and references binary buffers (.bin) and texture files (.png, .jpg) sitting alongside it. The data model is identical to GLB; the difference is layout — easier to inspect and edit, harder to ship as one asset.

• JSON scene descriptor with external binary and texture references
• Same PBR materials, animations, and skinning as GLB
• Convert to GLB for network delivery; keep as glTF for pipeline editing
• Used heavily in 3D content tooling and procedural pipelines

OBJ and glTF have overlapping capabilities, and most converters get the geometry right. The differences show up around materials, units, axis orientation, and what each tool downstream expects.

1. Blender (free, all platforms). Open Blender, File → Import → OBJ (.obj), then File → Export → glTF (.gltf). Blender has native importers and exporters for every format on this page except STEP (which needs the optional CAD Sketcher addon or a separate STEP-to-mesh pass). The export dialog exposes the settings that matter: scale, axis orientation, and whether to embed materials and animations.

Geometry-wise, OBJ and glTF carry the same essential data, so this conversion is reasonably lossless.

• Embedding a 3D model in a web page with model-viewer or Three.js
• Publishing to AR (Apple Quick Look, Android Scene Viewer)
• Sending an asset to a colleague who works in a web 3D pipeline