Free Online OBJ to STL Converter

Use our fast and 100% free OBJ to STL file converter to convert your OBJ 3D model file to the STL (Standard Triangle Language) format suitable for editing in 3D modeling applications or for 3D printing. Our tool supports batch conversion of your OBJ files, with up to 20 files at a time being processed.

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Select File(s)

Or drag and drop your files here to upload.
A maximum of 20 files can be uploaded at once.

Please note: Your OBJ file, once uploaded to our server, will be deleted 15 minutes after upload, so please download your converted OBJ file before this time.

Our tool will process all 3D geometry contained within your OBJ file, including vertices, faces, and normals. As the STL file format does not support materials and textures, if your OBJ file contains references to external texture files, these will be ignored. As OBJ files are text-based and the STL file format is binary, the resulting STL file will be much smaller, making it faster to store and process the STL file.

How to Convert your OBJ to STL Online?

Here are two simple steps to convert your OBJ to STL using our fast and free OBJ converter tool.

Upload your OBJ file

Click the "Upload a OBJ File" button, then select a OBJ to upload. The maximum file size is 100MB.

Download your STL

Click the download link to receive your STL file.

Frequently Asked Questions

How can I convert my OBJ file to STL?

First, click the "Upload..." button and select your OBJ file to upload. Your OBJ file will be uploaded to our servers. When the OBJ to STL conversion has completed, you can download your STL file right away.

How long does it take to convert my OBJ to STL?

We aim to process all OBJ to STL conversions as quickly as possible; this usually takes around 5 seconds; however, this can be longer for certain files, so please be patient.

How accurate is the OBJ to STL conversion?

We aim to provide the best conversion experience. Our tools are under constant review and development, with new features being added every week.

Comparing OBJ and STL Files

The OBJ and STL file formats are both capable of representing a 3D model, but their capabilities and suitability for specific tasks vary. Here we take a closer look at both formats, see what the fundamental differences are, and try to determine which is better suited to a particular task.

Features

In terms of features, the OBJ file format is capable of storing materials, i.e., surface rendering properties, in a separate MTL (short for material) file. This MTL file can also contain references to external texture files when dealing with textured surfaces. External texture files will tend to be either PNG or JPG files; however, there may be other formats used, such as TGA. STL files, on the other hand, have no support for object materials or textures, making the OBJ format the clear winner here if you need to store materials or textures with your 3D model.

The OBJ format also stores its geometry differently from the STL format. Whereas the STL format is a simple list of triangles, the OBJ format makes use of indexed lists of vertices, normals, and texture coordinates, which helps in the reuse of data and reduces the file size compared to the same model in the STL format.

A gingerbread 3D model with no materials stored in the STL format

A fully textured OBJ gingerbread house file

The OBJ formatted gingerbread house normal map

Uses

Due to their ability to contain materials and textures, OBJ files are generally used for storing models where colors and textures are present and for transferring 3D objects between applications. STL files can also be used as a medium for the exchange of simple 3D mesh data if that is all that is needed to be transferred. STL files really come into their own when it comes to 3D printing. Many 3D printing slicer software support the STL format, making it the better format for storing 3D objects you intend to send to a 3D printer.

Summary

Both OBJ and STL formats are popular and have been around for a long time, meaning they both command support amongst 3D modeling applications. Choosing between them depends on the task at hand. If you are intending to 3D print your model, then STL is the most suitable format; for anything else, the OBJ format is likely the best choice.

File format information for OBJ and STL

Extension	OBJ
Full Name	Wavefront
Type	3D Model
Mime Type	text/plain
Format	Text
Opens With	MeshLab, CAD Assistant, DAZ Studio

The OBJ file format is a 3D graphics file format used to define complex 3D models, including geometry, materials, and textures. OBJ files are text files, making them human-readable and easy to modify by hand. The downside to this ease of readability is that the files can become rather large when dealing with large or complex 3D models.

As mentioned, the OBJ format stores not only 3D model geometry but also materials and textures. These materials are usually defined in a separate file with the MTL file extension and specify geometry rendering details such as diffuse and specular color, transparency, and much more.

The OBJ material file can also reference external texture files. These are usually JPEG or PNG files; however, these can be older formats, such as TGA. Where materials are used, the OBJ file will also contain material names preceding the geometry faces they should be applied to. If textures are referenced, the geometry will also contain texture coordinates (UV) for each vertex.

OBJ Converter Capabilities

When converting 3D model or mesh files using our OBJ converter, we will attempt to convert color materials into a suitable format for use in the converted file.

Extension	STL
Full Name	Standard Triangle Language
Type	3D Model
Mime Type	application/vnd.ms-pki.stl
Format	Text
Opens With	Blender, MeshLab, CAD Assistant, DAZ Studio

The STL, or Standard Triangle Language, file format has been around since the '80s and is supported by most modern 3D modeling applications. In particular, the STL format has become something of a standard format within the area of 3D printing, despite the rise of more modern formats such as 3MF.

STL files come in two flavors: binary or text format. The text format is human-readable, making it easy to perform manual edits, but can lead to very large file sizes. As you can imagine, the binary format is much more compact and represents the majority of the STL files you are likely to encounter.

The format itself is very simple; the 3D model is represented by a sequential list of triangles, with each triangle defined with 3 points consisting of their X, Y, and Z positions, along with an additional vector that contains the face normal (the direction the face is pointing). There is an additional attribute block for each triangle; however, this is largely unused and thus unsupported.

STL Converter Capabilities

When converting your OBJ to STL, our tool will attempt to accurately convert any color or material information.

Information for converting from OBJ to STL

Your OBJ file will be converted to a STL file using our unified 3D model and mesh conversion tool. Our OBJ 3D tool performs accurate conversions of 3D elements such as vertices, faces, normals, and relevant material information. As both OBJ and STL support color material information, our tool will also attempt to convert the color information.