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Convert Your 3D Mesh/Model STL Files to OBJ

Convert your STL to OBJ file that can then be edited in most popular 3D modeling applications, such as Blender. Our tool works with all STL files, including the lesser-known formats that support individual face colors within the model. Our conversion tool can also batch convert multiple STL files; up to 25 files at a time can be converted.

To convert your STL to OBJ, click the Upload button above and select the STL file to convert. When selected, the file will be converted to an OBJ file, ready for download shortly afterwards. For more information about the STL to OBJ conversion process, including what 3D file features are supported, please see the conversion information section below for more information.

How to Convert your STL to OBJ Online?

Here are two simple steps to convert your STL to OBJ.

Upload a STL

Click the "Upload a STL File" button and select a STL to upload. The maximum file size is 100MB.

Download your OBJ

Click the download link once completed to receive your OBJ file.

Frequently Asked Questions

How can I convert my STL file to OBJ?

First click the "Upload..." button, select your STL file to upload. Select any configuration options. When the STL to OBJ conversion has completed, you can download your OBJ file straight away.

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

We aim to process all STL to OBJ conversions as quickly as possible, this usually takes around 5 seconds but can be more for larger more complex files so please be patient.

How accurate is the STL to OBJ conversion?

We aim to create the most accurate conversions with our tools. Our tools are under constant development with new features and improvements being added every week.

Is it safe to convert my STL to OBJ on ImageToStl.com?

Yes, of course! We do not store the STL file you submit to us. The resulting OBJ file, once created is deleted 15 minutes after upload and the download link will expire after this time.

Can I convert STL to OBJ on Windows, Linux, Android, iOS or Mac OS?

Yes! Our STL to OBJ tool will run on any system with a modern web browser. No specialist software is needed to run any of our conversion tools.

What if I am using an Ad Blocker, will that affect things?

Yes. Although you can use an Ad Blocker, if you like our STL conversion tool please consider white-listing our site. When an Ad Blocker is enabled there are some conversion limits on some of our tools and processing/conversion times will be longer.

What STL formats can I convert from?

You can convert from both text and binary STL files. If your STL file contains color information we will bring this over.

Will the OBJ file retain the textures from my STL file?

Yes! If your STL file contains textured geometry, the texture image files along with the texture coordinates (UV data) will be exported with the final OBJ file.

I have several STL files; can I batch convert my STL to OBJ?

Yes! Our STL tool supports full batch conversions. You can upload up to 25 and STL files at a time. Our tool will convert them all as quickly as possible. Once completed, you can either download the OBJ files individually or download them all in a single ZIP file.

Comparing STL and OBJ Features

 

STL Features

  • Mesh Geometry (Vertices and Faces)
  • Vertex Normals
  • Face Normals
  • Vertex Colors
  • Face Materials (Excluding textures)
  • Textures
  • Point Cloud
  • Multiple Objects Per File
  • Object Transforms (Translation, Rotation, and Scale)
  • Bones/Joints
  • Animations
  • Suitable for 3D Printing

OBJ Features

  • Mesh Geometry (Vertices and Faces)
  • Vertex Normals
  • Face Normals
  • Vertex Colors
  • Face Materials (Excluding textures)
  • Textures
  • Point Cloud
  • Multiple Objects Per File
  • Object Transforms (Translation, Rotation, and Scale)
  • Bones/Joints
  • Animations
  • Suitable for 3D Printing

File Format Information for STL to OBJ

ExtensionSTL
Full NameStandard Triangle Language
Type3D Model
Mime Typeapplication/vnd.ms-pki.stl
FormatText & Binary
ToolsSTL Converters, 3D Model Voxelizer, Create STL Animation, Compress STL, Text to STL, STL Viewer
Open WithBlender, Daz Studio, MeshLab, CAD Assistant

Description

The STL file format has its roots in the 1980's and is the native file format for 3D Systems stereolithography CAD software. The format defines a triangulated mesh with vertices and faces and is a popular format for sharing 3D printable model files.

There were several formats that attempted to extend the STL format, namely SolidView and VisCAM, whose formats included limited 15-bit color information for each mesh face, which is often ignored by most modern 3D software. The STL format can be either text or binary; our tools will support both formats.

STL Notes

Standard STL files do not contain material or color information, so this cannot be imported. There are, however, two formats (VisCAM and SolidView) that attempt to add color information to the STL file format. If our tool detects this additional color information, it will attempt to import this information.

Supported Features

  • Mesh geometry
  • Face colors via the VisCAM and SolidView formats
  • Binary and text versions are supported

Description

The OBJ file format, originally created by Wavefront Technologies and later adopted by many other 3D software vendors, is a simple text-based file format for describing 3D models/geometry. This data can include vertices, faces, normals, texture coordinates, and references to external texture files.

As the format is text-based, it is relatively straightforward to parse in 3D modeling applications. A downside of the text-based format is that the files can be rather large compared to similar binary formats such as STL and compressed files such as 3MF.

OBJ Notes

Our tool will save any material and texture files separately; these additional files will be included with your final OBJ file at the time of download.

Supported Features

  • Mesh geometry
  • Materials (Via an MTL file)
  • Textures (PNG, JPG, TGA formats)

A Comparison of STL and OBJ File Formats

Here we will compare the OBJ and STL file formats, look at the differences between the two formats, and highlight the reasons for choosing either format for a particular task. Before we begin, if you are not familiar with 3D modeling and the terminology behind it, we thoroughly recommend this great article that explains 3D modeling concepts and the terminology that goes with it.

Structure

Both OBJ and STL files can contain a 3D object represented by a series of triangles; however, how they go about storing this data is very different. Firstly, the OBJ format stores geometry as a collection of vertices and faces, with the vertices being drawn from a common pool, meaning a 3D object can use the same vertex on several faces without needing to define it multiple times. An STL file does not do this; in the STL format, each face has its own set of 3 vertices that cannot be re-used by other faces.

OBJ files support per-vertex normals; again, these are taken from a single common list that can be shared amongst several faces within the 3D object. STL files, however, do not support vertex normals but do support face normals. OBJ files can contain multiple 3D objects within the same file; the STL format, however, is a simple list of triangles with no ability to separate out individual 3D objects within a scene.

Supported Material

OBJ files have a lot of support for different object materials, including color and texture surfaces. STL files, however, do not officially support any material or texture capability. There are two applications, VisCAM and SolidView, that have their own implementation of limited 16-bit color support for individual faces within an STL 3D object. These capabilities are however not generally supported by other applications, so STL should be considered to be a plain geometry format with no support for materials of any kind.

A 3D wireframe model of a soldier

A 3D wireframe model of a soldier

The soldier model saved as an STL file

The soldier model was saved as an STL file with no materials or textures

The soldier model saved as an OBJ file with textures

The soldier model was saved as an OBJ file with textures

Editing

Both OBJ and STL files can be opened and edited in most popular 3D editing applications; just beware that, with the limitations of the STL format, if you open an STL 3D model and subsequently apply materials or textures to it, you will lose these if you then save it back to the STL format. Saving to the OBJ format will retain any textures and materials used by your 3D model, though be aware that with the OBJ format, materials are saved to a separate MTL (material) file and textures will be saved as separate image files (usually PNG or JPG).

File Size

With STL files, there are both binary and plain-text versions, with the text version being significantly larger, so we will discount this format as most STL files are binary anyway, and if not, you can use our STL compressor to convert your STL text-based file to an STL binary file. When comparing the STL binary format to the OBJ format (a text-based format), using a file that contains only mesh geometry with no textures or materials, the OBJ file usually comes out on top as offering the smallest file size of the two formats.

This may seem odd, as one would expect a binary format to be more efficient; however, the larger size of STL binary files compared to the text-based OBJ format is largely due to the duplicated vertex data, as this cannot be shared amongst the faces within the STL format.

Summary

Based on the smaller file sizes and the additional support for materials, textures, and more, we would say the OBJ format is the better format of the two for storing your 3D models. If you intend to 3D print your model, then the STL format would be the format to use, as this has widespread support amongst 3D printing slicer software. We go into more detail about converting from an OBJ to STL for 3D printing below.

How does it work?

Converting from the STL file format to OBJ can be a complex process, and any tool used for this conversion process needs to be able to handle a variety of data conversion tasks as well as identify any defects within the 3D model and fix them. Here we will explain the conversion process used by our tool to accurately convert your STL file to a valid OBJ 3D model. Let's start with the conversion process, which involves the following steps:

Step 1: Read the Source STL File

In its simplest form, an STL file can be either a plain text or binary file containing 3D data such as vertices, faces, normals, and more. When combined, these make up the 3D model you see on your screen.

For more information regarding the STL file format, please see this great article that goes into a lot of detail explaining the STL format.

Step 2: Process File Data

With the STL file data read, our tool generates an internal representation of the full 3D model and will attempt to fix any geometry issues encountered. Along with repairing any issues with the 3D model, the tool will remove any duplicated vertices and prepare the model for exporting to the OBJ format.

Step 3: Saving to the OBJ Format

The OBJ format has been around for many years and has become a standard format for 3D modeling. Most 3D modeling software can open OBJ files, which means our tool now needs to take the in-memory 3D model we created in step 2 and convert it to the OBJ format, ensuring it can be opened in all 3D modeling software with no compatibility issues.

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