Use the dimensioned example first
Open the STEP to STL tool and load its original 10 × 20 × 30 mm box. In millimetres, the reported size is 10 × 20 × 30 and the exported box contains 12 triangles. This is a deliberately simple fixture, not a customer model or a benchmark for complex CAD.
Export the same example in metres: the size becomes 0.01 × 0.02 × 0.03. The physical object is unchanged. If coordinates exported in millimetres are interpreted as metres, the object becomes 1,000 times too large.
Keep the unit decision with the file
STL does not provide a dependable standard unit declaration. A recipient needs to know what one coordinate unit means. In the STL Viewer, choosing a unit changes the measurement report; it does not rewrite the source file.
Record the source revision, chosen export unit and one known measurement together. A screenshot can help show the intended orientation, but it cannot replace the numeric dimension.
Choose detail using curves and the final use
Start with Standard. Inspect curved edges and the intended silhouette; use Fine when Standard visibly approximates a curve too coarsely. More triangles can increase processing and file size without improving a flat face.
The box is useful for scale, not for comparing curved-surface quality: its planar faces can remain 12 triangles at different settings. A denser export cannot restore a missing hole, an obsolete design or detail absent from the STEP source.
Know where the local converter stops
The Labs route accepts supported, self-contained STEP/STP files up to 5 MiB and tessellates geometry locally. It writes an STL mesh, not editable CAD features. Assemblies are flattened; original part naming, materials and the construction history are not retained.
Keep the native CAD and STEP source. A completed conversion is not a wall-thickness, watertightness or printability certificate. For manufacturing, inspect the result in the appropriate engineering or slicing application.
Make the next handoff explicit
For CGI, geometry is only one input. Send the current product revision, finish references and intended camera or deliverable alongside it. If you need OBJ instead, choose that route deliberately; this tool’s OBJ output is geometry-only and does not generate UVs or materials.