Converting OBJ to STL Files for 3D Printing: A Step‑by‑Step Guide

An STL is an ASCII format file that originated with 3D Systems' development of 3D printers. It was used as a means of communicating the printing requirements to the machines they were developing. STL files use the same basic methodology for communication of 3D objects that OBJ uses – but at a lower level of detail. It contains no color or texture information and has a slightly more clunky file structure. Mesh information for the triangles to construct the 3D representation contains 3-point (x-y-z) information for each vector. Plus the “normal” information, defining which face of the resulting triangle is outward facing. Non-standard binary formats of STL have been developed. This adds methods of encompassing color data into the file – but these are not commonly used.

Why Convert OBJ Files to STL Files?

Converting OBJ files to STL files is only necessary for home machines and the freeware slicer sector of the market. Most high-end printers can accept OBJ format files. But this is unusual in hobbyist and lower-cost machines, which are only set up to use the STL format.

How Long Does it Take to Convert an OBJ file to STL?

The time to convert an OBJ file and STL depends on the complexity of the file. Generally, it will only take a few seconds to complete a conversion. For most files, the setup of directories and uploading the files into software such as Spin 3D takes longer than the actual conversion. 

Which File Types can be Converted to STL?

A definitive list of 3D object file types that can be converted to STL format for 3D printing is quite extensive. The explosion of 3D rendering, gaming, character creation, product design, and product realization tools has been accelerating for two decades, and the list of file types that are open to conversion is many pages deep. If the file type is not supported by a certain converter, look for an update or another tool. STL is an old, simple, and tested format that is universal to 3D printing. Most file types contain much more information than STL, so this type of “downgrade” conversion is not challenging.

What are the Differences Between OBJ and STL formats?