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STEP to STL converter

Drop your .step / .stp file — we convert it to .stl right in your browser. Files never leave your computer.

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Drop your STEP file here
Accepts .step / .stp · converts to .stl

STEP vs STL— what's the difference?

STEP.step / .stp

ISO 10303 boundary-representation CAD format — the industry standard for exchanging precise, parametric solid models between engineering tools.

Strengths
  • 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
Limitations
  • 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
Typical use: Engineering CAD exchange, mechanical design, supplier handoff
STL.stl

Triangle-mesh format that every 3D printer slicer understands. Geometry only — no units, colours, or assemblies.

Strengths
  • Universal 3D printing format — Cura, PrusaSlicer, Bambu Studio all speak STL
  • Tiny, simple, extremely fast to load
  • Great for meshing workflows, simulation pre-processors, quick previews
Limitations
  • Triangulated approximation — curved surfaces lose precision
  • No colour, material, or assembly data
  • One shell per file by convention (multi-body gets flattened)
Typical use: 3D printing, rapid prototyping, mesh-based workflows

How to convert STEP to STL

  1. 1
    Drag a .step or .stp file onto the drop zone (or click to browse). Everything runs locally — your CAD never leaves the machine.
  2. 2
    Inspect the model in the live 3D preview. Orbit, zoom and check the triangle count to confirm the conversion looks right.
  3. 3
    Click Download .STL to save a binary STL. Open it straight in your slicer and print.

FAQ

Is my STEP file uploaded to a server?

No. Conversion happens entirely in your browser using WebAssembly (occt-import-js) and Three.js exporters. Nothing is sent to our servers and nothing is stored.

Does STL lose precision compared to STEP?

Yes — this is fundamental to the formats, not to our converter. STEP stores exact B-rep curves; STL stores triangles. For 3D printing the triangulation is fine. For re-import into CAD, keep the original STEP.

Is the STL output binary or ASCII?

Binary STL — roughly 5× smaller than ASCII and faster to load in slicers. Every mainstream slicer reads binary STL natively.

What's the maximum file size?

There is no hard limit we impose — the ceiling is your browser's memory. In practice STEP files up to a few hundred MB work on a desktop; very large assemblies may need a machine with 8 GB+ RAM.

Why do assemblies come out as a single STL?

STL has no concept of assemblies or parts — it is just a bag of triangles. All bodies are flattened into one mesh on export. If you need per-part files, split the assembly in your CAD tool first.

Can I convert STL back to STEP here?

No — and nobody else can either, honestly. Going from mesh to B-rep is reverse-engineering, not conversion; you would need a tool like Fusion 360's Mesh → BRep or Ansys SpaceClaim, and the result is rarely as clean as the original.

Related converters

STL → OBJSTEP → GLBSTEP → OBJOBJ → STL