Tools · 3D Converter

Convert STL to OBJ online

Some programs and pipelines take OBJ but not STL. The converter reads the STL triangles, can turn them from millimetres Z-up into metres Y-up or keep the numbers as they are, and writes an OBJ with normals plus a small MTL file with one neutral material.

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Drop a file to see it here.

Convert to

FBX is not offered as output: browsers cannot write clean FBX files. Every Grab3D library model comes with a ready FBX download. Browse models

3D printing preset: millimetres, Z-up, origin at the bottom center

STL stores geometry only. All visible parts are merged into one binary STL.

Up axis Unit

Origin Recompute normals (smooth, sharp edges above 30°) Simplify materials (base color and color texture only) Bake colors and textures into vertex colors

Read the source as

Up axis of the source Unit of the source

Auto uses the file information: STL is millimetres Z-up, 3MF uses the unit stored in the file with Z-up, FBX uses its unit scale, everything else metres Y-up.

How it works

Drop one or more .stl files. Binary and ASCII both work.
Choose the output: metres and Y-up suit Blender and game engines, millimetres and Z-up keep the coordinates of the STL unchanged.
Convert, download the ZIP and unpack the .obj and .mtl into the same folder.

What is kept and what to watch

STL has no UVs, colours or textures, so none can appear in the OBJ. You get geometry, normals and one grey material.
Every triangle is written with its own corners, as in the STL. Merging duplicate vertices is a job for a 3D program.
Recompute normals smooths the faceted look of scans and organic shapes, sharp edges above 30 degrees stay sharp.

Other conversions

Frequently asked questions

Will the OBJ have textures or colours?

No. STL only stores triangles, so there is nothing to carry over. Paint or texture the model in a 3D program after the conversion.

Which unit should I pick?

It depends on where the OBJ goes. Blender and most engines work in metres. For CAD tools or another print workflow, choose millimetres so the numbers stay the same as in the STL.

Why is there an MTL file in the ZIP?

OBJ references its materials in a separate file. The MTL holds one neutral material, so importers that expect it find it and do not report a missing file.