Conversion

You may arrive here with a file that opens in one app and refuses to open in the next one. Or you found a nice model online, but it’s in a format you don’t know. Or, you’re working with someone and they say stuff like “I’ll need an STL, buddy”, or maybe they say “you have to do a FBX with all materials inside”. It’s a jungle, honestly. But we will do our best to have you covered. And if we don’t, reach out!

At Convert3D we sit in the middle: upload the file you have, choose the format the next tool (or person!) wants, and check what came out.

Convert one file

1. Open convert3d.org/convert.
2. Drop the file on the upload area, or choose it from your computer.
3. Choose the format you need.
4. Download the converted file.

Convert3D reads the source format from the filename extension. If it does not recognize the file, check that first. Renaming model.fbx to model.obj does not make it an OBJ file. Annoying, but true.

If you close the page before downloading, run the conversion again. The web app is built around the current conversion result, not a file manager of old conversions.

Check the preview before trusting the file

The preview is your first answer. If Convert3D understood the source file, the preview should show the model you expected.

This is where you check if everything is alright:

• Yes, the model loads.
• Yes, the model is facing the right way.
• Important parts are not missing.
• Materials or textures are there and they look great.
• The model has the right size.

If the preview is already wrong, downloading another final format usually will not fix it. But give it a shot, just to be sure. Try again with the missing sidecar files (in a zip, or just drag everything in), check the source in the app that made the model, or pick a target format that fits the data better.

Pick the format the next app wants

This is where a lot of failed conversions start. The source file may be fine. The target format may simply be the wrong one.

When in doubt, try glb first. It is a good intermediate format for many tasks, and one of the most modern and compatible ones. The industry folks really likes it so it’s making its way into more and more apps as we speak.

If the target software will not open it

This is one of the most common problems: Convert3D creates a file, but the next app refuses to open it.

Check the boring things first:

• Did you choose the exact format the target app asks for?
• Does the target app support that format version?
• Did the source model already look right in the preview?
• Are you sending a mesh to a tool that expects CAD solids?
• Are you sending a 2D drawing where the app expects a 3D model?

If the target app gives you a vague error, convert to glb and inspect the model first. If the GLB looks right, the issue is probably the target format or the target app. If the GLB looks wrong, go back to the source file.

STL is not a CAD solid

STL is a mesh format. It is made of triangles.

That matters if you are trying to turn a messy STL into a clean CAD file. Converting stl to stp or another CAD format may help a tool import the file, but it will not recreate the original editable solid model. The original CAD surfaces are already gone.

If CAD solids matter, start from step, stp, sldprt, sldasm, or another CAD source format when you can. If all you have is STL, inspect the result carefully in the target CAD app.

Bring the files that belong together

Some formats travel as a small pile of files.

obj is the usual offender. The .obj file may contain the geometry, while the .mtl file describes the materials and separate image files hold the textures. Upload only the OBJ and you may get the shape, but not the surface. It is like moving house and leaving the furniture behind.

gltf can also point to external .bin files and textures. Some CAD and scene formats reference linked assets too.

If textures disappear after conversion, look for missing files before trying a different output format.

Batch similar files

Batch conversion works best when the files want the same treatment.

Ten obj files to glb is a good batch. A folder of CAD parts to stl is fine too. A mixed folder where some files need glb, others need dwg, and half the textures are missing is not a batch. That is a small cleanup project.

Use batch conversion after you have tested one file and know the settings are right.

Be careful with DWG and DXF

DWG and DXF are awkward because they can contain 2D drawings, 3D models, or both. The extension alone does not tell you enough.

When DWG or DXF is the output format, Convert3D can write:

• 3D / Mesh for a 3D object.
• 2D / Multiview drawing for front, top, and right-side drawing views.

If you expected a 3D object and got a flat drawing, check the output mode. If you expected a drawing and got a mesh, choose 2D / Multiview drawing.

See DWG and DXF for the longer checklist.

If textures are missing

Start with the boring causes. They are usually the right ones.

• The source format may not store textures.
• The target format may not support the same material features.
• The source file may reference texture files that were not uploaded.
• An .obj file may be missing its .mtl file.

For web display, try glb. It keeps the model, materials, and textures together in one file.

If conversion fails

Usually it is one of these:

• The source format is not supported.
• The target format is not supported for that source.
• The file extension is wrong.
• The source file is damaged.
• Sidecar files are missing.
• The source uses features the target format cannot represent.

Open the source file in the app that created it. If it does not open there, Convert3D probably cannot read it either.

See Troubleshooting for fixes.