Is this STL to STEP converter free, and is my file uploaded?
It is free, and the conversion happens in your browser. Your file stays on your computer and is not uploaded.
STL to STEP
STL → STEP: bring scan/print meshes into CAD workflows.
Workspace
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About This Tool
STL to STEP converter: turn an STL mesh into a STEP file you can open in CAD software. Flat areas become clean flat faces, curved areas stay as small flat pieces, and a mesh with no holes opens as a solid. The conversion runs in your browser and your file is not uploaded.
About Configuration Options
General Settings
| Option | What it does | Default / range |
|---|---|---|
Up axis | Determines the 'up' axis of the exported model. Different 3D software uses different conventions. Selecting the wrong system may cause the model to lie on its side.
| Z-up |
Rotation X | Rotate the model around the X axis (degrees). Useful for correcting axis misalignment or print orientation. | 0°-180° – 180° |
Rotation Y | Rotate the model around the Y axis (degrees). Useful for correcting axis misalignment or print orientation. | 0°-180° – 180° |
Rotation Z | Rotate the model around the Z axis (degrees). Useful for correcting axis misalignment or print orientation. | 0°-180° – 180° |
Rotation Application | Choose how rotation is written to the exported model. Baking into vertices rewrites all vertex coordinates so every export format (including geometry-only formats such as STL and STEP) applies it consistently; root node transform keeps the original vertex coordinates, which is friendlier to animated or skinned models, but formats that ignore node transforms (such as STEP) won't apply the rotation.
| Root node transform |
STEP Output Settings
| Option | What it does | Default / range |
|---|---|---|
Precision | Tessellation tolerance when converting BREP surfaces to mesh. Lower values keep finer surface detail (larger files); higher values produce a coarser mesh. Range 0.0001-0.1. | 0.0010.0001 – 0.1 · step 0.0001 |
What you get from STL to STEP
Convert STL to STEP right in your browser; the file stays on your device. You get a STEP file that CAD programs can open: flat areas become clean flat faces, while curved areas stay as many small flat pieces. Smooth curves are not rebuilt, and there is no feature history or dimensions to edit.
| Item | Details |
|---|---|
| Input → output | STL (binary or ASCII) → STEP (.step, the same format as STP) |
| What STL stores | Only tiny triangles, with no units |
| What the STEP contains | Faces and edges CAD can select; a solid body if the mesh has no holes, surfaces if it does |
| Curved areas | Still made of small flat pieces |
| Units | Millimetres |
| Privacy and price | Converted in your browser, not uploaded; free, no sign-up |
- Mesh
- A shape made only of small triangles, like an STL file.
- Facet
- One small flat piece of a mesh.
- Solid
- A closed body CAD can cut, extrude and measure volume on.
- Surface model
- Faces without a closed volume; what you get when the mesh has holes.
- Watertight
- A mesh with no holes or gaps, needed for a solid.
- STEP / STP
- Two extensions for the same CAD exchange format.
How to get the most out of it
Good uses
- Bringing a downloaded or 3D-printed part into CAD to design a bracket, case or adapter that fits it.
- Sending a model to a supplier or machine shop that only accepts STEP files.
- Using a scanned object as a solid reference for fit checks.
Before you convert
- STL has no units and the STEP is saved in millimetres, so a model made in inches will open 25.4 times too small.
- Repair holes in the mesh first if you need a solid body.
- Curved models produce STEP files much larger than the STL.
- Very large scans with millions of triangles may be more than your browser can handle; simplify the mesh first if the conversion fails.
After converting: what to do in CAD
Common programs such as SolidWorks, Fusion 360, FreeCAD or Onshape can import the file.
- Import the STEP as a part or body.
- Check the size and scale by 25.4 if the model was made in inches.
- Check it came in as a solid; if it shows as surfaces, repair the STL and convert again.
- Sketch on the flat faces, cut, extrude or combine it with other parts, or use it as a reference. For a 2D drawing, create the views in your CAD program.
What it's not for
How it works, simply: the converter tidies up the mesh, merges triangles that lie on the same flat surface and joins all faces into one STEP file.
- If you have the original CAD file, export STEP from it directly. Going from STL to STEP cannot bring back smooth curves.
- For real curved surfaces or an editable design from a scan, use reverse-engineering software such as Geomagic Design X or SolidWorks ScanTo3D.
- If you only want to 3D print or view the model, keep it as STL or 3MF.
Frequently Asked Questions
View all FAQsCan I convert STL to STEP online without installing anything?
Yes. Open this page, choose your STL file and download the STEP file. There is nothing to install and no account needed.
Will it open as a solid in SolidWorks, Fusion 360 or FreeCAD?
Yes, as long as the STL has no holes. A mesh with holes opens as surfaces instead, so repair it first if you need a solid.
What does the precision setting do?
It decides how many decimal places are kept for each point. The default suits most models; a rougher setting makes the file slightly smaller without changing the shape you see.
My part opens at the wrong size in CAD. Why?
STL files have no units, and the STEP is saved in millimetres. If your model was made in inches it will look 25.4 times too small; scale it up by 25.4 in your CAD program.
Why is the STEP file bigger than the STL?
Each triangle of the mesh becomes its own face in the STEP file, and STEP is stored as text, so the result is usually several times larger. Reduce the mesh in your modeling app first if size matters.
Format Information
Input format
- Extension:
- stl
- Full Name:
- Stereolithography
- Type:
- 3D Mesh
- Format:
- STL (Binary / ASCII)
- Tools:
- Cura、PrusaSlicer、Chitubox、Simplify3D
- Open With:
- Slicer Software、MeshLab、Windows 3D Viewer、STL Viewer Online
- Description:
- STL is the de facto standard mesh format in 3D printing, storing only triangular surface data since 1987, without color, texture, or material. Almost all slicers (Cura, PrusaSlicer, Bambu Studio, ChiTuBox) and printers directly support STL, ensuring its enduring popularity. Two classic pitfalls: STL lacks unit definitions, making millimeters and inches indistinguishable on disk; always verify scale in your slicer. It also has ASCII (readable but 4-6x larger) and binary (compact, default) encodings. For multi-color printing, materials, or parameters, switch to 3MF, which carries richer print information while maintaining slicer compatibility.
Notes:
- Does not support colors, textures or materials
- No unit definition; verify scale in your slicer
- ASCII format is 4-6× larger than binary
Supported Features:
- Triangle mesh only, simple and universally compatible
- Binary and ASCII encoding options
- Directly importable into Cura, PrusaSlicer, Chitubox, etc.
Output format
- Full Name:
- STEP (Standard for the Exchange of Product Model Data)
- Type:
- CAD Model
- Format:
- STEP
- Tools:
- SolidWorks、Fusion 360、FreeCAD
- Open With:
- 3D Model Viewer、STEP Viewer
- Description:
- STEP (ISO 10303) is an international standard for CAD data exchange, preserving precise geometry with NURBS and solid modeling. Widely used in mechanical design and manufacturing, it retains parametric features and assembly structures, unlike mesh formats (STL/OBJ), enabling lossless transfer between CAD software. STEP suits engineering precision, not real-time rendering. Browsers and game engines require conversion to mesh. Recommended workflow: design in CAD, export STEP for archiving, then convert to STL/GLB for preview or printing. .stp and .step are identical variants, and compressed STEP (.stpz, .stepz, .zstep) is also supported.
Notes:
- CAD software required for editing parametric features
- Not suitable for real-time or web rendering
Supported Features:
- ISO-standard CAD exchange format
- Precise parametric surface modeling
- Widely supported by CAD/CAM/CAE software
- Suitable for engineering and manufacturing