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Convert STL to OBJ

Convert STL to OBJ in seconds. Free, no signup, no watermark, no file-size limit. Your file is processed in your browser and never uploaded.

At a glance

Source
STL
Target
OBJ
Where it runs
Your browser
Cost
Free, unlimited
Account
Not needed
STL

Converter

STL to OBJ

On device

Drop one or more stl mesh files.

or select stl mesh

Your file never leaves this browser

    The details

    What happens when you convert between 3D formats

    The mesh format for 3D printing. A list of triangles and nothing else. The mesh is read, and its geometry, materials and animation are written out in the target format, converting units along the way. The result is a a text-based 3d mesh format that has been around since the 1990s and refuses to die, produced entirely inside your browser.

    What survives

    • The geometry, though often at a lower polygon count
    • Materials and textures where the target format supports them
    • The animation, where the target format supports it

    What changes

    • The polygon count, because many formats cannot hold a high-density mesh
    • The material model, which differs between formats

    Where it goes wrong

    • Unit conversion is the classic trap — a model that was in centimetres can arrive in metres
    • Materials written by a modern renderer may fall back to a plain colour in an older format

    Why anyone would do this

    The model has to live in a different tool, and the tool does not read the format you have.

    About the format

    The mesh format for 3D printing.

    Either an ASCII list of facets or a binary array of triangle records with normals and vertex coordinates.

    Where it is good
    • Almost every 3D printer and slicer reads it
    • Very simple, so there is nothing to get wrong
    • Fast to load into a slicer
    Where it falls short
    • No colour, no texture, no material information
    • No units — the file is just numbers and you have to know the scale
    • Enormous for a curved object because a curve is thousands of triangles
    You will find it on
    3D printers, slicers, CAD packages, maker spaces

    The thing people miss

    STL has no units at all, which is why the same file can print 10 mm tall in one slicer and 10 cm tall in another.

    About the target

    A text-based 3D mesh format that has been around since the 1990s and refuses to die.

    A plain text file listing vertices, texture coordinates, normals and the faces that join them, plus material references.

    • Readable — you can open it in a text editor and understand it
    • Holds texture coordinates and material references
    • Accepted by almost every mesh tool

    Real jobs

    What people are actually doing with STL

    Sending a model to a 3D printing service

    A quick shape for a workshop

    Checking a 3D model before ordering a print

    Specification

    The details, in one table

    Source formatSTL — STL mesh
    Target formatOBJ — Wavefront mesh
    Typical source size1–100 MB
    RunsIn your browser
    Account neededNo
    WatermarkNone
    File extension.stl → .obj

    How to

    STL to OBJ, step by step

    1. 01

      Add your stl mesh

      Drag the file onto the drop zone, or tap to browse. Only one file is needed.

    2. 02

      Choose the OBJ settings

      Set the OBJ-specific options — everything happens locally, so the speed is your device, not a queue.

    3. 03

      Download the result

      The finished OBJ downloads to your device. Nothing is uploaded and nothing is retained.

    Also available

    STL converts into

    GLBglTF binary

    Questions

    STL conversion questions

    What actually happens to my STL file when I convert it to OBJ?

    The mesh is read, and its geometry, materials and animation are written out in the target format, converting units along the way. So the STL file is unpacked, the content is laid out, and the result is written out as OBJ. The geometry, though often at a lower polygon count survives unchanged.

    Will converting STL to OBJ reduce the quality?

    For this particular conversion, not in the way you would expect. The geometry, though often at a lower polygon count — the STL content is not re-encoded in a lossy way. The only thing that changes is the format it is stored in.

    Is my STL file uploaded to a server?

    No. This STL to OBJ conversion runs as JavaScript inside your browser tab. The file is read from your device and the result is written back to your device, so there is no upload step, no file-size limit and no copy of your STL file on any server.

    Do I need an account or will there be a watermark?

    Neither. There is no sign-up step, no email capture and no watermark on the output. The only limits are the ones your own device imposes.

    What is the most common mistake people make when converting STL to OBJ?

    Unit conversion is the classic trap — a model that was in centimetres can arrive in metres

    Why would somebody convert STL to OBJ at all?

    The model has to live in a different tool, and the tool does not read the format you have. In short: sending a model to a 3d printing service

    Something most people do not know about STL?

    STL has no units at all, which is why the same file can print 10 mm tall in one slicer and 10 cm tall in another.