Free Online OBJ to STL Converter

Best for: quick, no-install conversion

1. Upload your .obj file or drag-and-drop it onto the canvas.
2. Preview the 3D mesh in the viewport to verify geometry.
3. Click Convert to STL - processing runs on our secure servers.
4. Download the STL instantly. Your uploaded file is auto-deleted.

Best for: editing or repairing the model first

1. Open Blender and use File → Import → Wavefront (.obj).
2. Optionally edit, decimate, or repair non-manifold geometry.
3. Select the object and File → Export → STL (.stl).

Best for: print-ready models, if your slicer accepts OBJ

1. Most modern slicers (Cura, PrusaSlicer, Bambu Studio) import OBJ directly.
2. File → Import → OBJ, then File → Export → Export STL.
3. If your slicer struggles with the OBJ, use this page to convert first.

STL is much larger than the OBJ

Expected. OBJ shares vertices across faces efficiently; binary STL stores every triangle's three vertices independently (12 floats per triangle vs. ~3-4 shared in OBJ). The resulting STL is typically 2-3× larger. The geometry is identical, only the encoding differs.

Slicer reports non-manifold or holes

The source OBJ mesh had open edges or duplicate faces. Run a mesh repair in Blender (Mesh → Cleanup) or Meshmixer, then re-export STL.

Model prints at wrong scale

OBJ has no unit metadata. Open the STL in your slicer and set the correct scale manually (e.g., if the OBJ was modeled in meters and your slicer expects mm, scale by ×1000).

Textures or colors are missing

By design - STL cannot store color or material. The geometry is preserved correctly. If you need color, use 3MF instead, or keep the original OBJ with its MTL and textures.

How do I convert an OBJ file to STL?

Upload your .obj file using the tool above, preview it in the 3D viewport, then click Convert to STL. The file is processed on our secure servers and the STL is ready for download instantly.

What is the difference between OBJ and STL?

OBJ (Wavefront Object), introduced in the 1990s, is a text-based format that stores mesh geometry, per-vertex normals, material references (MTL), and texture coordinates. STL, created in 1987 for stereolithography, stores only triangle geometry - no color, material, texture, or units. OBJ files are typically 30-50% smaller than equivalent binary STL files because OBJ shares vertices across faces while STL duplicates all three vertices per triangle. OBJ is widely used in CAD, 3D scanning, and animation; STL is the universal format for 3D printing slicers.

Can a slicer import OBJ directly?

Many modern slicers can. PrusaSlicer, Bambu Studio, and Cura all support importing OBJ files directly via File → Import. However, some older or specialized slicers only accept STL. If your slicer rejects the OBJ, use this tool to convert it first.

How do I convert OBJ to STL in Blender?

Open Blender → File → Import → Wavefront (.obj) to load your file. Select the object, then File → Export → STL (.stl). Blender reads OBJ natively and exports clean binary STL. Optionally decimate or repair the mesh first for better printability.

Will textures and colors be preserved?

No. STL stores only surface geometry (triangles) - no color, material, or texture data. The tool parses OBJ materials and textures correctly but only the mesh shape is written to STL. If you need color, keep the original OBJ or convert to 3MF instead.

What is an OBJ file?

OBJ is a geometry definition format developed by Wavefront Technologies. It stores 3D mesh data - vertices, faces, normals, and texture coordinates - in a human-readable text format. Material definitions live in a companion .mtl file, and textures are separate image files (PNG, JPG). OBJ is supported by virtually every 3D application including Blender, Maya, 3ds Max, MeshLab, and CAD software.

Is the OBJ to STL converter free?

Yes. The tool is free to use with an instant 3D preview and no watermarks. Upload your OBJ file, preview it, and convert to STL in seconds.

Are my files safe when uploading?

Yes. Your file is transmitted over SSL and processed on our secure servers. After conversion, the uploaded file is automatically deleted - we do not store your 3D models permanently.

How long does it take to convert OBJ to STL?

Conversion typically completes in a few seconds after uploading. The preview renders instantly in your browser, and server-side processing handles the conversion quickly. Larger models with millions of triangles may take slightly longer.

Does the tool support OBJ files with MTL materials?

Yes. The converter correctly parses OBJ geometry. Materials and textures defined in the companion MTL file are recognized for rendering in the preview, but only the mesh geometry is exported to STL since STL cannot store material data. If your OBJ references a .mtl file, make sure both files are available when uploading.

What is the maximum file size?

Up to 50MB per file. Conversion runs in your browser, so processing speed depends on your device's CPU and available memory.

Which format is better for 3D printing: OBJ or STL?

STL is the better choice for 3D printing because every slicer reads it natively. OBJ offers richer data (colors, materials, normals) that 3D printers cannot use. If your model exists as OBJ, convert it to STL before slicing - or check whether your slicer accepts OBJ directly.

Is the converted STL manifold and print-ready?

The mesh geometry is preserved from your OBJ. If the source model is manifold (watertight), the STL is print-ready. OBJ meshes from CAD or scanning are sometimes non-manifold, so verify watertightness or run a mesh repair before printing.

What devices and browsers are supported?

Any modern browser (Chrome, Firefox, Safari, Edge) with WebGL support, on any operating system - Windows, Mac, Linux, iOS, or Android. No software installation or plugins required.