STLBenchFree online GLB to USDZ converter
GLB to USDZ, for the half of your visitors on iOS
Drop a .glb or .gltf and download a .usdz, built in this tab with nothing uploaded. The scale does not change — glTF and USD both count in metres, so the factor is exactly one — and that is the most important sentence on the page, because AR anchors a model at life size in a real room and a thousandfold error there is not subtle. What you get is the zipped USD package Apple's Quick Look opens straight from a link, with the GLB's embedded textures carried into it.
- 100% free
- No signup
- Quick Look ready
- Scale factor 1
- Nothing uploaded
Drag a file anywhere on this page to open it. F fits the view, W switches shading, G the grid, R spins it.
How to convert GLB to USDZ
Three steps, and the last one is not optional.
Drop the .glb or .gltf
Both are read. What comes back is a .usdz — a zip holding a USD scene description and its textures, which is the package Apple's Quick Look opens directly from a web link or a message.
The scale does not change, and that is the point
glTF and USD both count in metres, so the factor is exactly one and the coordinates cross untouched. It matters more here than anywhere else on this site: AR places the model at life size against a real room, so a file that is off by a thousand does not look small, it looks like the app is broken.
Test it on an actual iPhone
Serve the file and open the link in Safari on iOS, or AirDrop it to a device. Quick Look is the only implementation that matters for USDZ, and the only honest test is the one it performs.
Technical specifications
| Reads | .glb and .gltf — self-contained files |
|---|---|
| Writes | .usdz — a zipped USD package with its textures |
| Unit | Metres both sides; scale factor 1 |
| Axis | Y-up, written as USD's upAxis — nothing is rotated |
| Kept | Geometry, materials, textures, per-object names |
| Opens in | iOS Quick Look, macOS Preview, Reality Composer, model-viewer's iOS path |
| File size | No fixed limit — past 100 MB you are told what it will cost this tab, then it opens |
Frequently asked questions
What is USDZ actually?
A zip archive with a specific layout: one USD scene description file plus the textures it references, stored uncompressed so the runtime can memory-map them. USD itself is Pixar's scene format, open-sourced in 2016 and now the backbone of Apple's 3D stack. The .usdz wrapper is Apple's contribution — a single file that iOS can open from a link without asking anybody to install anything.
Why does iOS need its own format?
Because Apple built Quick Look around USD before glTF had won, and has kept it. The practical consequence for anyone publishing a model is that AR requires two files: a .glb for Android's Scene Viewer and the web, and a .usdz for iOS. Google's model-viewer element accepts both and picks the right one per device, which is why the pair is the standard deliverable rather than a choice between them.
My model is lying on its side.
That is an axis convention, and it is worth knowing which one bit you. glTF is Y-up and this writes USD as Y-up too, so nothing is rotated here. But a model that started life in a Z-up package — Blender, most CAD, 3ds Max — may already have been rotated once by whatever wrote the glTF. The fix is upstream: set the orientation in the source and re-export, rather than rotating twice and losing track.
Do textures come across?
Those the GLB carries, yes — that is one of the format's advantages, since a GLB embeds its images rather than referencing them. They are written into the package alongside the scene. What Quick Look supports is a subset of what glTF allows, so exotic material extensions may render more plainly on iOS than they do in a desktop viewer.
Can I go back from USDZ?
Yes, and it is the rarer direction because reading USD is considerably harder than writing it. That page exists on this site, and it is worth knowing about if a client sends you a USDZ as the only copy of an asset.
Is my file uploaded?
No. The GLB is parsed and the zip assembled in this tab. AR assets are usually products that have not launched, and there is no server here to keep a copy of one.
About needing two files to show one model
Web AR settled into an awkward compromise that nobody designed on purpose. Android takes a GLB and hands it to Scene Viewer. iOS takes a USDZ and hands it to Quick Look. Neither will accept the other's file, and there is no sign of that changing, so publishing a model in AR means shipping both and letting the page decide. Google's model-viewer element does the deciding for you: give it a src and an ios-src and the right one loads on the right device.
USD is a genuinely serious piece of technology underneath the awkwardness — Pixar built it to compose entire films out of layered scene descriptions, with references, variants and overrides that a format like glTF does not attempt. A USDZ for a product photo uses almost none of that. It is USD wearing a zip, chosen because Apple needed a single-file container that iOS could open safely from an untrusted link.
If your model started as a print file rather than a web one, the STL route gets you to a GLB first. And if you have been handed a .usdz and need it somewhere other than an Apple device, the reverse conversion is on this site too.
Where the conversion happens
Every number on this page is worked out by JavaScript running in the tab you are reading it in. The model you open is read straight off your own disk — it is never uploaded, logged or kept, which is also why these tools carry on working after you disconnect from the network.
One clause specific to this page: an AR asset is nearly always a product being prepared for launch, complete with the name it will ship under. The zip is put together from a file that never left your machine.