Convert OBJ to STL

Drop in a .obj and get a binary STL back, ready for PrusaSlicer, Cura or Bambu Studio. Parsed and written on your own machine.

OBJ → STL

Drop a OBJ file

or click to choose one. Your file never leaves your browser.

Runs locally · nothing uploadedOBJ

Runs entirely in your browser. Your file is never uploaded, and there is no sign-up.

What changes, and what does not

Geometry passes through unchanged. What goes away is everything OBJ carried that STL has no way to represent: UV coordinates, material references, and the separation between named objects and groups. STL is one bag of triangles by design, so a multi-object OBJ arrives as a single merged shape.

That is not a loss for printing. A slicer only ever reads the triangles. It is a loss if you were hoping to keep textures, in which case keep the OBJ or export 3MF instead.

The .mtl question

An OBJ usually sits next to a .mtl file describing its materials, which in turn points at texture images. None of that reaches an STL, so you do not need the sidecar files here. Converting the .obj alone produces exactly the same result.

Before you print

Check the mesh, not just the conversion. OBJ files from photogrammetry and AI generators frequently contain holes, self-intersections, or non-manifold edges that render fine and slice badly. Every major slicer has a repair pass, and it is worth running:

PrusaSlicer: right-click the object, then Fix by Netfabb.
Cura: Extensions, Mesh Tools, Fix simple holes.
Bambu Studio: right-click, Fix model.

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Frequently asked

Why convert OBJ to STL at all?

Slicers want STL. OBJ is a modelling and interchange format that carries UVs and material references, none of which a 3D printer uses. Converting drops what the printer ignores and leaves the triangles it needs.

Do I need the .mtl file?

No. STL has no concept of materials or colour, so the .mtl is irrelevant to the output. You can convert the .obj on its own and lose nothing that would have survived the format anyway.

Is the result printable as-is?

It will open in a slicer, which is not the same as being printable. This converts the mesh faithfully rather than repairing it, so run the repair pass in PrusaSlicer, Cura or Bambu Studio if the model came from a scan or an AI generator.

Is anything uploaded?

No. The OBJ is parsed and the STL written in your browser, using your own machine. Nothing is transmitted and there is no sign-up.

What about scale?

Both formats are unitless, so the numbers pass through unchanged. Slicers generally read them as millimetres. If the model lands a thousand times too big or too small, that is the mismatch, and scaling in the slicer fixes it.