GLB to USDZ

GLB to USDZ for AR on iPhone and iPad

Apple's AR Quick Look, the viewer built into iOS and iPadOS, opens USDZ files and nothing else. Tap a USDZ in Safari, Messages, Mail or Files and the model appears in AR on the table in front of you, with no app to install. GLB, the format the rest of the web and Android use, doesn't open there. To show the same model to iPhone users, you convert GLB to USDZ.

The converter does this in your browser. Drop a GLB, check it in the preview, and download a USDZ that opens in Quick Look. The model isn't uploaded anywhere.

What is converted

glTF and USD both use physically based materials, so the look carries over well. The main loss is motion.

Meshes and hierarchy

Kept.

PBR materials

Converted to USD's preview surface material: base color, metallic, roughness, normal, occlusion, emissive and opacity, with their texture maps.

Textures

Embedded in the USDZ, so it stays a single file. Textures larger than 2048 px are scaled down.

Animation

Not exported. The USDZ is a static model in the rest pose stored in the file, which for a rigged character is usually a T-pose.

Advanced glTF materials

Effects from glTF extensions such as transmission (glass), sheen or iridescence have no equivalent in the output and fall back to the basic material.

Compressed input

Draco and Meshopt compressed GLB files are read and written out uncompressed. A GLB that requires KTX2 textures can't be read; one that only uses them opens without those textures.

How to convert GLB to USDZ

1. Drop the .glb onto the converter. A glTF with separate .bin and texture files works too; drop all the files together.

2. Check the preview. What you see is close to what Quick Look will show.

3. Convert and download the .usdz. Both formats are Y-up, so the model keeps its orientation and no axis fix is needed.

4. Test it: AirDrop or message the file to an iPhone or iPad and tap it. It opens in Quick Look with an Object and an AR tab.

Putting the USDZ on a website

On iOS Safari, a link to a USDZ with rel="ar" opens straight into AR Quick Look instead of downloading. The link must wrap an image, which becomes the tap target:

<a rel="ar" href="/models/chair.usdz"><img src="/images/chair.jpg" alt="Chair"></a>

If you already use <model-viewer> for the GLB, add the converted file with the ios-src attribute and the AR button will use it on iPhones and iPads.

Serve the file with the MIME type model/vnd.usdz+zip. Some servers don't know the .usdz extension and send it as a generic download, which stops Quick Look from opening it.

If it looks wrong in AR

Quick Look places the model at real-world size, treating one unit as one meter, just as glTF does. Most surprises come from that.

Going the other way, for Android and the web? Use USDZ to GLB.

Model is the size of a building

The GLB was in centimeters, often because it came from an FBX. A 50 cm chair stored as 50 units shows up 50 meters tall. Scale the model in Blender or your source app and export the GLB again before converting.

Model is tiny

The GLB was modeled in millimeters or at an arbitrary small scale. Same fix in the other direction.

Textures missing

Check the preview first: if they're missing there, the GLB references files you didn't drop in, or uses KTX2 textures as an optional extension, which are skipped. Re-export the GLB with PNG or JPEG textures.

Model doesn't move

Animation isn't exported. The USDZ is a static snapshot.

Glass looks solid

Transmission isn't carried over. Use a material with opacity instead if you need see-through parts.