Does the STL file store millimeters as its unit?

No. STL has no unit metadata. This tool normalizes STEP coordinates to millimeters, so downstream software should interpret the output values as millimeters.

Does STL preserve editable STEP data?

No. STL contains tessellated triangles and does not preserve assemblies, parametric features, modeling history, materials, tolerances, or analytic surfaces.

Why can a valid STEP file still fail?

Conversion cost depends on model complexity and generated triangles. The tool stops at its file, face, triangle, or time limits instead of risking an unresponsive browser.

STEP to STL Converter - Convert STEP and STP Online

Convert a STEP or STP CAD file into one binary STL mesh locally in your browser. Source units are normalized to millimeters; STL does not retain CAD semantics or unit metadata.

Drag and drop a STEP or STP file here

Accepts one .step or .stp file

Maximum file size: 20.00 MiB. Conversion starts only when you select Convert.

Browser-local CAD conversion

Your file is read and converted in a dedicated browser worker. BaseToolbox does not upload or store it, and the CAD engine loads only when conversion starts.

Browser safety limits

Each job stops after 30 seconds, or if tessellation produces more than 100,000 triangles. Complex assemblies may reach a limit even when the file is under 20 MiB.

STL is a triangle mesh, not editable CAD

The output flattens supported bodies into one mesh. It does not preserve assembly hierarchy, part names, parametric features, modeling history, materials, tolerances, or analytic surfaces. Keep the original STEP file.

Convert STEP and STP files to STL locally

This converter reads CAD geometry in a dedicated browser worker, normalizes the declared model units to millimeters, tessellates supported bodies, and writes one binary STL without uploading the source model.

How STEP to STL conversion works

Choose one STEP or STP file up to 20 MiB. The file stays in your browser.
The local CAD engine reads the declared units, converts geometry to millimeters, and tessellates supported bodies into triangles.
Download one binary STL mesh and configure downstream software to interpret its coordinate values as millimeters.

What is lost when STEP becomes STL

STL stores triangle geometry rather than the original CAD model. Assemblies, separate part identity, editable features, modeling history, materials, tolerances, and analytic surfaces are not preserved.

Related 3D tools

Open the STL Viewer Open the general 3D Model Converter

STEP to STL FAQ

Does the STL file store millimeters as its unit?: No. STL has no unit metadata. This tool normalizes STEP coordinates to millimeters, so downstream software should interpret the output values as millimeters.
Does STL preserve editable STEP data?: No. STL contains tessellated triangles and does not preserve assemblies, parametric features, modeling history, materials, tolerances, or analytic surfaces.
Is my STEP file uploaded?: No. The file is read and converted in a dedicated browser worker. BaseToolbox does not upload or store the model.
Why can a valid STEP file still fail?: Conversion cost depends on model complexity and generated triangles. The tool stops at its file, face, triangle, or time limits instead of risking an unresponsive browser.