STEP to USDZ converter
Drop your .step / .stp file — we convert it to .usdz right in your browser. Files never leave your computer.
Why convert STEP to USDZ?
USDZ is the only format that lets a webpage drop a 3D model straight into AR on an iPhone — no app install, no account. Safari intercepts the <a rel='ar' href='...usdz'> link and launches Quick Look full-screen. If a CAD part needs to end up floating on someone's desk through an iPhone camera, STEP → USDZ is the path.
Who runs this conversion
Marketing / e-commerce teams putting "View in AR" on product pages, furniture and appliance retailers adding room-scale previews, and design reviewers who want to see a physical-scale model in their own space before tooling.
Things that commonly go wrong
- USDZ assumes real-world metres. A STEP in millimetres will land correctly, but check scale — AR will happily plant a pen the size of a couch otherwise.
- Default grey PBR only. Apple's AR renderer makes the lack of textures more obvious than on web GLB — downstream texturing in Reality Composer helps.
- Keep USDZ small. iOS drops quality on mobile previews above ~25 MB. Decimate tessellation before exporting for mobile AR.
Technical note for this tool
Tessellates STEP via OCCT, builds a USD scene tree, and packs it zip-aligned into a valid .usdz per Apple's spec. Writes geometry only — PBR materials stay neutral.
STEP vs USDZ— what's the difference?
ISO 10303 boundary-representation CAD format — the industry standard for exchanging precise, parametric solid models between engineering tools.
- Exact curved surfaces (NURBS / B-rep) — no tessellation loss
- Assembly hierarchy, part names and metadata preserved
- Supported by every major MCAD tool (SolidWorks, Inventor, Fusion, Creo, NX…)
- Open, vendor-neutral ISO standard
- Not directly consumable by 3D printers or game engines
- Files are larger and slower to open than mesh formats
- Requires a CAD kernel to read — no native browser support
Apple's AR-native package format — a zipped USD scene that iOS Safari renders directly via AR Quick Look without any app install.
- Native iOS AR Quick Look (tap → floating 3D in your room)
- PBR materials + animations preserved
- Single self-contained file, easy to email or link
- Android / desktop need a separate path (typically GLB)
- Tooling outside Apple's ecosystem is still catching up
Deeper context on the formats
STEP — where it came from
Standardised as ISO 10303 in 1994 to replace the aging IGES format. Application Protocols AP203 (configuration-controlled design), AP214 (automotive), and AP242 (modern merge of both) define what data travels with the geometry — AP242 is the current default for new exports and is what most fabs expect in 2026.
- Assemblies exported with external references break when the .step file is moved without its companion files — always export as a single-file package (AP242 XML or monolithic .step).
- Kernel-to-kernel round-trips (e.g., Inventor → STEP → Fusion → STEP) can introduce tiny sliver faces and edge-tolerance drift; keep the original parametric file as the source of truth.
- PMI (product manufacturing information — GD&T, annotations) only rides along in AP242 — older AP203 exports strip it silently.
Real-world use: Mechanical suppliers quote from STEP, contract manufacturers program CNC toolpaths from STEP, and electronics vendors publish component 3D models as STEP on Digi-Key and Mouser. Any time a mechanical engineer hands off a design to a machine shop or an injection-mold vendor, it ships as STEP.
USDZ — where it came from
Announced at WWDC 2018 as Apple's bet on mainstream AR. USDZ is a zipped Pixar USD (Universal Scene Description) scene, chosen because USD already powered Pixar's film pipeline and could describe both simple product models and full film sets. The Quick Look integration means any <a rel="ar"> link on an iPhone spawns a full-screen AR view.
- iOS Quick Look will refuse to display USDZ files that exceed ~250 MB on older devices — keep textures under 2K unless you have a reason.
- Material translation from GLB → USDZ is lossy in both directions; subtle differences (clearcoat, transmission) round-trip badly.
- Desktop Safari can preview USDZ but the AR placement only works on actual iOS hardware — test on an iPhone, not the simulator.
Real-world use: Apple Store product pages, furniture retailers (Wayfair, IKEA iOS path), sneaker AR try-on, museum-exhibit companion apps, and any shop that wants "View in your space" on iPhone.
How to convert STEP to USDZ
- 1Drop a .step or .stp file. The CAD kernel runs in WebAssembly locally — nothing uploaded.
- 2Preview the tessellated model in 3D. Check the Scene Tree to confirm the hierarchy is right.
- 3Click Download .USDZ. Share the file via AirDrop, iMessage, or link — tapping on iPhone launches AR Quick Look.
FAQ
What is USDZ good for?
USDZ is Apple's native AR format. Drop the file in iCloud / Dropbox / any web link, and tapping it on an iPhone launches AR Quick Look — your model floats in the room with no app install required. Great for product previews, retail, and client presentations.
Does it work on Android?
No — USDZ is iOS-specific. For Android, convert STEP to GLB instead (we have a landing for that too) and use Scene Viewer.
How do I trigger AR Quick Look from a website?
Host the .usdz file and link it with an anchor: `<a rel="ar" href="model.usdz"><img src="preview.jpg"></a>`. Safari on iOS intercepts the click and launches AR. The main 3D viewer here does exactly this — load a STEP, export USDZ on an iPhone, and it launches AR automatically.
Is my CAD uploaded anywhere?
No. STEP is parsed by occt-import-js in your browser; USDZ is generated locally by Three.js' USDZExporter.
How big will the USDZ be?
Typically 1–5× the source STEP depending on tessellation density. USDZ compresses the zipped USD payload efficiently.