STL Converter

3D files come in many formats and each tool prefers its own. Slicers want STL or 3MF, Blender and game engines like OBJ and GLB, and scanners often produce PLY. This converter reads STL (ASCII or binary), OBJ, GLB, GLTF with embedded data, 3MF and PLY meshes, and writes STL, OBJ, GLB or PLY. It runs in your browser, so your designs are never uploaded.

STL stores a plain triangle mesh with no color or units. It is the universal format for 3D printing. OBJ stores geometry and can reference materials; here only the geometry is used. GLB is the single-file version of glTF, built for the web, AR and games, and it can carry colors and textures. PLY is common in scanning. 3MF is a package that can hold several objects, colors and settings, and it is input only here: all objects are merged into one model and colors are dropped.

STL, OBJ and PLY files are written in millimeters. GLB files are written in meters, as the glTF standard requires. Use the "Units in the file" selector (mm, cm, m or inches) to tell the converter how to read your input; GLB and GLTF are assumed to be meters, everything else millimeters. glTF/GLB use Y as the up axis while STL and 3MF usually use Z, so when you convert between them the model is rotated to stand correctly in your slicer. This is on by default and can be switched off.

After converting, check the size shown beside the preview. If it is off by a factor of 10, 25.4 or 1000, the units are the cause.

Conversion keeps shape only. Colors, textures and animations are lost when writing STL, OBJ or PLY, and an OBJ's .mtl colors are ignored when reading. A GLTF that points to a separate .bin file is not supported, so export a .glb instead. A PLY point cloud without faces cannot be turned into a solid model. The converter does not repair meshes, so holes and non-manifold edges in the source stay in the output. Large files depend on your device's memory.