LOCAL FILE WORKBENCH

Convert STEP or STP to STL

Tessellate STEP or STP CAD geometry into a binary STL locally, with explicit units and controlled mesh quality.

STEP to STL Converter OnlineIDLE

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Supported input and output

Self-contained STEP / STP B-rep input; binary STL output in millimetre coordinates. Supported solid bodies, shells and nested assembly placements.

Choose the tessellation for your next use

Curved CAD faces become flat triangles. Draft, Balanced and Fine use linear deflection settings of 0.5, 0.1 and 0.02 mm respectively, together with angular limits. A smaller tolerance can preserve more surface detail at a higher triangle count. These settings control tessellation; they are not a guarantee of printer accuracy.

How to use this tool

Choose your STEP or STP file and review the tessellated preview.
Choose a quality preset; apply changes and check the resulting triangle count.
Convert to STL and download. Import the STL as millimetres in your next application.

Limitations to check

STEP describes CAD surfaces; STL is a triangle approximation. This conversion loses CAD topology, names, colors and design metadata.
Declared STEP units are read and OCCT normalizes placements and geometry to mm. STL does not encode units: select millimetres when importing the output.
All imported parts/shells are combined without boolean union or repair. External references, mixed/missing units and unsupported constructs are rejected.
Fine quality costs more time and memory. Output stays subject to the same triangle limit, and float32 collapse or incomplete face tessellation stops export.

File and processing limits

STEP/STP up to 10 MiB, 100,000 entities and 10,000 source faces.
Up to 500,000 vertices, 250,000 triangles and 128 mesh parts/shells; binary STL output up to 64 MiB.
45 seconds per job. CAD WebAssembly memory is capped at 256 MiB; JavaScript and rendering use additional memory.

Processing happens in this browser; your file and filename are not uploaded. Cancel, reset or replace the file to stop its worker. Downloads are generated locally.

Questions about this workflow

Does STP need a separate converter?

No. STEP and STP filename extensions use this same workbench. A supported file must include its length units; the exported coordinates are normalized to millimetres.

Will the STL retain editable CAD features?

No. STL contains triangles, not analytic surfaces, CAD topology or a feature history. Keep the original STEP file if you need further CAD editing.

CAD import uses OCCT / occt-import-js. Open-source notices and library source.