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Convert STL to OBJ Online: Mesh to Mesh

Convert an STL triangle mesh to OBJ. The conversion does not recover a precise CAD solid or add reliable units.

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Capabilities and limits

  • Convert an STL triangle mesh to OBJ. The conversion does not recover a precise CAD solid or add reliable units.
  • Conversion preserves supported geometry rather than native parametric feature history; verify output units, completeness and geometry.
  • Files are uploaded for server processing; support depends on format, version and geometry.
  • Viewing and measuring do not require an account. Free conversion points are valid for 90 days. Sign in to convert, save files across devices or create share links.
On this page

Convert STL to OBJ when another mesh tool expects OBJ. Both files are triangles. This does not turn a mesh back into a STEP solid.

Treat the STL as a mesh

STL has no reliable unit declaration. CADProps measures STL coordinates as millimetres. Confirm a known dimension before converting if the scale matters.

Convert STL to OBJ

Choose OBJ and download the mesh. The triangles are copied into OBJ. Materials, textures and a CAD feature tree are not created.

Do not expect a solid

An open or inconsistent STL stays a mesh. Volume, if shown, is an approximation and only applies to a closed, consistent mesh. Use the original CAD or STEP file when you need an exact solid.

Input formats: STL

Points: viewing and measuring are free. A new account gets 3 free conversion points; free points are valid for 90 days. One point converts one file to every output format for 30 days, and a failed or incomplete conversion uses none. See pricing.

Open this tool

General steps for uploading, viewing, sectioning, measuring, converting and exporting are explained once in How it works. This page covers what is specific to this file type.

Real CADProps screenshots

The screenshots show the English interface. Captions and instructions describe the same operations.

Convert CAD files — box.stl
Convert CAD files — box.stl

Sample source and verification

Properties — stl-to-obj.zip · 10 × 20 × 30 mm · 6,000 mm³ · 2,200 mm²
Properties — stl-to-obj.zip · 10 × 20 × 30 mm · 6,000 mm³ · 2,200 mm²

When a result needs another check

Viewing can start without an account. Conversion, account storage and share creation require signing in. Temporary files expire after the displayed retention period. Read the privacy statement for server processing and deletion, and the accuracy notes before using numerical results. Do not assume that hiding a part, clipping it or exploding an assembly changes the exported source geometry.

When a result needs another check · Input formats

Continue with a related task

Original article: CADProps · https://www.cadprops.com/tools/stl-to-obj/

A reproducible example

Convert a generated closed STL box measuring 20 × 30 × 40 mm to OBJ. Confirm the bounding box and note that the 24,000 mm³ volume is approximate and depends on mesh closure.

Repository-generated samples are synthetic test models. Verify your own model's units and geometry before using results.

Supported formats
All formats and limits →

Questions about this task

Can I convert STL to OBJ online?

Yes. Upload an STL file, choose OBJ and download the mesh.

Will STL to OBJ create a STEP solid?

No. OBJ is still a triangle mesh. Converting the mesh does not reconstruct precise CAD curves or a solid model.

Does the OBJ file gain units?

No. Neither STL nor OBJ declares a reliable unit. CADProps assumes millimetres when it measures these meshes.

Do I need an account to convert files?

View and measure without an account. Register or sign in to convert, save files and create share links. Recipients can view shared models without an account.

Related reading

Checks that help with this file.

All guides →
Measurement

OBJ Mesh Units and Volume: Check Scale and a Closed Shell

OBJ does not declare reliable units. See how millimetres are assumed, when mesh volume is only an approximation, and why OBJ is not a CAD solid.

Read the guide →Troubleshooting

STL Volume Zero or Missing? Check the Mesh Is Closed

Diagnose STL files with zero, missing or unreliable volume by checking watertightness, inconsistent faces, units and export quality before calculating mass.

Read the guide →Measurement

Do STL Files Have Units? How to Fix mm vs Inch Scale

No. STL has no standard unit declaration, so 25 can mean 25 mm or 25 inches. Diagnose mm-versus-inch scale errors and verify dimensions before printing or manufacturing.

Read the guide →