GLB vs STL vs glTF vs OBJ: Choosing a 3D Format for the Web

· 6 min read · AcademicAR Team

Four 3D file types, each with the kind of model it holds

“What format should I export?” is the first question when you want to share a 3D model online. Here’s a researcher-friendly comparison of the formats you’ll meet.

STL — geometry only

STL is the lingua franca of 3D printing and many segmentation tools. It stores triangles and nothing else: no units, no color, no texture, no material, no separate parts. It’s perfect as a source format from CT/MRI or CAD, but on its own a web viewer can only show it as a plain gray shape, and you have to say whether it was made in millimetres or metres.

OBJ — geometry plus simple materials

OBJ adds UV coordinates and references an .mtl material file plus texture images. It’s widely supported and human-readable, but it’s verbose and splits a model across several files, which is awkward to host. Like STL, it has no units.

A bare triangle mesh next to the same part with materials

FBX — rich but proprietary

FBX (from Autodesk) carries geometry, materials, a hierarchy of parts, the modelling unit, rigs, and animation. It’s common in CAD and animation pipelines but is a proprietary binary that needs conversion for the open web.

STEP — exact CAD geometry

STEP (.step, .stp) is the neutral exchange format of mechanical CAD. It stores exact surfaces (not triangles) and the assembly structure, so it must be tessellated into a mesh before any viewer can draw it. See what a STEP file is and how to open it.

glTF / GLB — built for the web

glTF is the “JPEG of 3D”: an open standard designed for efficient delivery and real-time rendering. GLB is its single-file binary form — geometry, materials, textures, named parts, and animation all in one .glb, in metres. It supports physically based rendering (PBR) so materials look right, and it compresses well with Draco.

USDZ — Apple’s AR format

USDZ is the packaged form of Pixar’s Universal Scene Description and is what iPhone and iPad AR Quick Look opens. You rarely author it directly: you convert from GLB. See GLB to USDZ.

One GLB file opening in a browser and on a phone

At a glance

Format Colour & textures Parts Units Web-ready
STL No No No Needs conversion
OBJ Yes (MTL + images) Groups No Needs conversion
FBX Yes Yes Yes Needs conversion
STEP Colours only Yes Yes Needs tessellation
GLB Yes Yes Metres Yes
USDZ Yes Yes Yes iPhone/iPad AR

So which should you use?

  • Working/source format: keep your STL, OBJ, FBX, or STEP from the original pipeline.
  • Sharing on the web: convert to GLB. It’s one file, renders fast, supports real materials, and is what browser viewers and Android AR expect.
  • iPhone AR: add a USDZ generated from the GLB.

The good news: you don’t have to convert by hand. Upload STL, OBJ, FBX, STEP, or GLB to AcademicAR and it produces an optimized GLB (Draco-compressed geometry, compressed textures) plus a USDZ for iOS AR — so your readers get a fast, correct model regardless of what you started from. Step-by-step guides: STL to GLB and OBJ and FBX to GLB.

Frequently asked questions

What is the difference between glTF and GLB?

They are the same format in two packagings. glTF is a JSON file that can reference separate binary and image files; GLB packs everything into one binary file, which is easier to host and share.

Is GLB better than STL?

For viewing and sharing, yes: GLB carries colours, materials, parts, and real units, and it compresses well. STL is still the standard for 3D printing, so keep it for the printer.

Which 3D format is best for the web?

GLB. It is the format browsers, web viewers such as model-viewer, and Android AR load directly. Add USDZ for AR on iPhone and iPad.

Upload any format and get a web-ready GLB automatically.

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