USD to STL Converter
FileFlip converts USD to STL entirely inside your browser, using Assimp compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert a USD file to STL?#
- Drop your USD file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to STL and the conversion starts on its own. FileFlip downloads 11.2 MB of WebAssembly the first time and nothing after that, then runs Assimp on your own machine.
- Save the STL file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting USD to STL lose quality?#
Not in the sense of pixels or samples. Converting USD to STL rebuilds the file in STL's own model rather than re-encoding it, so everything STL can represent comes through exactly and anything it cannot has to be dropped. Expect the geometry to be exact, and anything the target has no place for, such as a rig, to be left behind.
Is it safe to convert USD files online?#
Yes, because nothing is uploaded. FileFlip converts USD files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What USD to STL actually does to the file#
Converting USD to STL runs on Assimp, downloads 11.2 MB of WebAssembly the first time and nothing after that, rebuilds the file in the target's own model, and drops materials, textures and skeleton and animation.
| Engine | Assimp |
|---|---|
| Conversion path | One step: USD → STL |
| Downloaded to your browser | 11.2 MB, once, then cached by your browser |
| Quality | Rebuilt in the target's model |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Materials | Dropped | The target format has nowhere to put it. |
| Textures | Dropped | The target format has nowhere to put it. |
| Skeleton and animation | Dropped | The target format has nowhere to put it. |
Worth knowing before you start:
- the target stores triangles and nothing else, so materials, colours, and texture coordinates have nowhere to go
- if the source carries a skeleton or animation, this target has no place to store it
What is a USD file?#
A USD file holds a 3D scene written in Pixar's Universal Scene Description language, saved under the generic .usd extension, which can contain either the ASCII text encoding or the binary Crate encoding without the extension telling you which.
Use the plain .usd extension when a tool needs to write out a scene without committing to a specific ASCII or binary encoding.
Convert to USDA when a layer needs to be read or diffed as text, or to USDZ when the file needs to open directly in AR Quick Look.
What is an STL file?#
An STL file is a triangle mesh created by 3D Systems in 1987 for its stereolithography 3D printers, storing nothing but a flat list of triangle facets and their normals, with no colour, material or unit of measurement attached.
Use STL when the only destination is a 3D printer's slicer, which is all the format was designed to feed.
Convert STL to 3MF when colour, material or unit information needs to travel with the geometry, since STL has nowhere to put any of it.
USD to STL questions people ask#
What is the difference between USD, USDA, USDC and USDZ?
USD is Pixar's Universal Scene Description format, and USDA, USDC and USDZ are its three concrete file forms: USDA is the ASCII text encoding, USDC is the binary Crate encoding, and USDZ is a zero-compression ZIP package of USD layers plus their textures and other assets. A plain .usd file can be either ASCII or Crate underneath; USDA and USDC exist so the encoding is explicit in the extension.
Is a USD file text or binary?
A .usd file can be either, since USD's generic extension doesn't fix the encoding the way .usda or .usdc do. Opening the file in a text editor is the fastest way to tell: readable text starting with #usda means ASCII, anything else means it's the binary Crate form.
Can I open a USD file in Blender?
Yes, Blender has built-in USD import and export, handling .usd, .usda and .usdc files including their materials and, in recent versions, animation.
Do I need Pixar's own software to use USD files?
No. Pixar's usdview and command-line tools are the reference implementation, but USD support is built into Blender, Autodesk Maya, and NVIDIA Omniverse, among others, so opening or editing a USD file doesn't require Pixar's tools specifically.