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STEP vs STL
STEP exchanges product geometry and related data between CAD systems. STL represents a surface as a triangular mesh. They serve different tasks: design-data exchange and preparing geometry for 3D printing.
Which format should you choose?
Consider STEP for exchanging geometry between CAD tools. Use STL when delivering a triangular mesh to a slicer or 3D printer, and verify units, dimensions, mesh closure, and normals.
Good fit for STEP
Cross-CAD 3D exchange
- Sending solid parts and assemblies to a partner using another CAD system
Good fit for STL
3D printing
- Passing a printable surface model from CAD to a slicer
Basic information
| Field | STEP | STL |
|---|---|---|
| Extension | .step, .stp | .stl |
| MIME type | model/step | model/stl |
| Common uses | Cross-CAD 3D exchange | 3D printing |
| How to open | Open in a STEP-capable CAD viewer and inspect units, solids, surfaces, assemblies, and attributes. | Open in a 3D viewer or slicer and verify dimensions and mesh integrity. |
| Export or convert | After importing into native CAD, verify holes, surfaces, assembly structure, and units; feature history may not survive. | When converting from OBJ or FBX, verify retained detail, units, scale, and triangle orientation. |
Choose by use case
Sending solid parts and assemblies to a partner using another CAD system
Cross-CAD 3D exchange
STEPPassing a printable surface model from CAD to a slicer
3D printing
STLKey point 1
STEP is intended for product-data exchange and can carry CAD geometry and related information.
More on the differencesKey point 2
STL approximates surfaces with triangles and is widely used to pass models to 3D-printing workflows.
More on the differencesMore on the differences
Exporting STEP to STL tessellates curved surfaces. Check mesh resolution and dimensions, and use another format or accompanying data if material, color, or design history matters.
- STL generally does not preserve full product-editing history or rich material and color information.
- A mesh that looks correct may still have holes, incorrect normals, or unit-scale problems that affect printing.
Frequently asked questions
Should I send STEP or STL to a 3D printer?
Follow the service's requirements. STL is commonly accepted for a mesh, while STEP may be accepted by workflows that convert CAD geometry themselves.