Key Takeaways:

STL to SLDPRT in SOLIDWORKS

An STL file is a mesh, while an SLDPRT file is a native SOLIDWORKS part. You can import an STL into SOLIDWORKS, but converting it into a clean, editable solid may require additional steps.

Method 1: Import STL as a Solid

Open SOLIDWORKS.
Go to File → Open.
Select your .STL file.
Click Options in the Open dialog.
Under Import as, select Solid Body.
Click OK → Open.
If the STL is suitable, SOLIDWORKS creates a solid body.
Go to File → Save As.
Select SOLIDWORKS Part (.SLDPRT).

Method 2: Import as Graphics Body

If the STL is too large or complex:

File → Open → STL → Options → Graphics Body

This is useful for viewing the model, but it isn’t a normal editable SOLIDWORKS solid.

For a Fully Editable Model

If you need to modify dimensions and features, simply converting STL → SLDPRT usually isn’t enough.

A better workflow is:

STL → Mesh → Reference Geometry → Rebuild Features → Native SOLIDWORKS Part

You may need to use tools such as ScanTo3D or reverse-engineering techniques to recreate sketches, surfaces, and solid features.

Important Tip

If you only need to 3D print the model, keep it as STL.

If you need to edit dimensions, add holes, change features, or create engineering drawings, rebuild it as a native SLDPRT.

Key Takeaway:
STL → Import → Solid Body → Save As .SLDPRT
Complex STL → Reverse Engineering → Rebuild → Native .SLDPRT

STL to SLDPRT in SOLIDWORKS

An STL file is a mesh-based 3D file format commonly used for 3D printing, scanning, reverse engineering, and sharing 3D models. An SLDPRT file is SOLIDWORKS’ native part format.

SOLIDWORKS can import an STL file, but the result depends on the import settings and the quality of the STL mesh. A key point is that simply saving an STL as an SLDPRT does not automatically create a fully editable parametric SOLIDWORKS model.

There are several approaches depending on what you need.

ScanTo3D: Convert STL to Editable SOLIDWORKS Features (YouTube): Walkthrough on using built-in reverse engineering tools to extract planar/cylindrical surfaces from complex faceted mesh models.

Method 1: Import STL as a Solid

If the STL is relatively simple and has a suitable mesh, you can attempt to import it as a solid body.

Step 1: Open SOLIDWORKS

Launch SOLIDWORKS and select:

File → Open

Step 2: Select the STL File

Browse to your:

.STL

file.

In the file-type selection, choose:

STL (*.stl)

Step 3: Open the Import Options

Before opening the file, select Options.

SOLIDWORKS provides different import options for mesh files.

Depending on the version and available functionality, you may be able to import the STL as:

Graphics Body
Mesh Body
Solid Body
Surface Body

Step 4: Select Solid Body

If the STL geometry and mesh quality allow it, choose the appropriate Solid Body import option.

Click:

OK → Open

SOLIDWORKS will attempt to convert the STL mesh into a solid body.

Step 5: Save as SLDPRT

Once the model has been imported successfully, select:

File → Save As

Choose:

SOLIDWORKS Part (*.SLDPRT)

You now have an SLDPRT file containing the imported geometry.

Important

The resulting solid may still be difficult to edit parametrically because the original STL contains triangular mesh facets rather than native SOLIDWORKS features.

Method 2: Import as Graphics Body

For large or complex STL files, importing the model as a Graphics Body can be much faster.

Step 1: Open the STL

Go to:

File → Open

and select the STL file.

Step 2: Choose Graphics Body

In the STL import options, select:

Graphics Body

This allows SOLIDWORKS to display the mesh without attempting to convert every triangle into a conventional solid.

Step 3: Work With the Imported Mesh

The model can be viewed and used as a reference.

This approach is useful when you need to:

Inspect a scanned model
Compare geometry
Take measurements
Use the STL as a reference
Prepare a model for reverse engineering

Limitation

A graphics body is not equivalent to a normal SOLIDWORKS solid feature model.

You generally cannot edit it like a conventional part containing:

Extrude
Revolve
Fillet
Chamfer
Hole
Sketch

features.

Method 3: Import as a Mesh Body

Depending on your SOLIDWORKS version and available mesh functionality, you may also be able to import the STL as a Mesh Body.

This is useful when you want to retain the mesh structure while working with it inside SOLIDWORKS.

Mesh-based workflows can be useful for:

3D scanning
Reverse engineering
3D printing
Inspection
Reference geometry
Complex organic shapes

However, a mesh body is still fundamentally different from a conventional parametric SOLIDWORKS model.

For a Fully Editable Model

If your goal is to obtain a fully editable SLDPRT model, simply importing the STL is usually not enough.

An STL contains a triangular representation of the object’s surface. It generally does not contain the original design history, sketches, dimensions, constraints, or feature relationships.

A typical reverse-engineering workflow is:

STL → Mesh/Reference → Extract Geometry → Create Sketches → Build Features → Fully Parametric SLDPRT

Step 1: Import the STL

Bring the STL into SOLIDWORKS as an appropriate mesh or reference body.

Step 2: Inspect the Geometry

Check:

Overall dimensions
Mesh quality
Orientation
Missing surfaces
Holes
Irregular areas
Design features

Step 3: Create Reference Geometry

Use the imported model to establish:

Planes
Sections
Axes
Reference points

These references can help you reconstruct the original design.

Step 4: Create Sketches

Create sketches based on the STL geometry.

For example, you might reconstruct:

Circles
Rectangles
Profiles
Holes
Curves
Cross-sections

Step 5: Rebuild the Features

Use normal SOLIDWORKS features such as:

Extruded Boss/Base
Extruded Cut
Revolve
Sweep
Loft
Fillet
Chamfer
Hole Wizard

The goal is to replace the mesh representation with native CAD features.

Step 6: Add Dimensions and Constraints

Add appropriate:

Dimensions
Geometric relations
Design intent
Constraints

This makes the reconstructed model easier to modify.

Step 7: Save as SLDPRT

Finally, save the reconstructed part as:

.SLDPRT

You now have a much more editable SOLIDWORKS model.

Example

Suppose you have an STL of a mechanical bracket.

STL

The file contains thousands of triangular facets representing the bracket.

Simple Conversion

STL → Import → Solid/Mesh → Save as SLDPRT

This gives you an SLDPRT containing the imported geometry, but it may not behave like a model originally created in SOLIDWORKS.

Reverse Engineering

STL → Import → Reference → Sketch → Extrude → Cut → Fillet → Dimensions → SLDPRT

This produces a model with native SOLIDWORKS features that can be edited more easily.

STL vs SLDPRT

Feature	STL	SLDPRT
File type	Mesh	Native SOLIDWORKS part
Triangular facets	✅	Not normally the design representation
Parametric features	❌	✅
Sketch history	❌	✅
Dimensions/constraints	❌	✅
Feature tree	❌	✅
Easy modification	Limited	✅
3D printing	Excellent	Can be exported
Reverse engineering	Reference	Excellent after reconstruction

Which Method Should You Use?

Requirement	Recommended Method
Just view the STL	Graphics Body
Use STL as a reference	Graphics/Mesh Body
Need a basic solid	Import as Solid
Large/complex scan	Mesh Body
Need editable CAD features	Reverse Engineering ⭐
Need a fully parametric SLDPRT	Rebuild the model ⭐

Important Tips

1. Check STL Quality

A very dense STL may contain hundreds of thousands or millions of triangles. This can make conversion and editing slow.

2. Check Units

STL files don’t reliably carry the same unit information you may expect from native CAD files. Always verify the imported model’s dimensions.

For example, a model intended to be:

100 mm

should not accidentally appear as:

100 inches

or another incorrect size.

3. Repair the Mesh

If the STL contains:

Holes
Non-manifold edges
Gaps
Intersecting triangles

the conversion to a solid may fail or produce problematic geometry.

4. Don’t Expect the Original Feature Tree

An STL generally cannot recreate the original SOLIDWORKS design history automatically.

The original:

Sketch → Extrude → Fillet → Chamfer

feature structure is not stored in the STL.

Frequently Asked Questions (FAQs)

1. Can SOLIDWORKS convert STL to SLDPRT?

Yes. SOLIDWORKS can import STL data and the resulting model can be saved as an SLDPRT, depending on the import method and model complexity.

2. Is an imported STL fully editable?

Not necessarily. An imported STL is fundamentally mesh-based and does not contain the original parametric design history.

3. Can I convert STL directly into a feature-based model?

Not in the same way as opening an original native CAD file. For a truly editable model, you generally need to reconstruct the important geometry using SOLIDWORKS features.