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How to reduce the file size of .STL


When 3D printing your object, your goal is to get the best result possible. If you are printing end parts or visible parts, you might need to get detailed objects, with the best quality and resolution possible. While during the development of these parts the choice of the technology and of the 3D printing material is important, everything actually starts with the quality of your file. But sometimes overly detailed 3D files can be too heavy to print!

Here we are going to give you some important advice and tell you why the size of your STL file matters. Discover how to reduce the size of your STL files, without sacrificing quality!

What is an STL file?​

If you want to use 3D printing to create your three-dimensional object, you will have to get a specific file. The STL file format is the most used file format in 3D printing, but there are plenty of other file formats you could use to 3D print using our online 3D printing service, such as the OBJ file format. This 3D format represents the raw surface of the model, with small triangles. The more triangles will be used, the most detailed and complex your structure will be, but also the heavier your file might be!

In order to create an STL or OBJ file, you will have to use 3D modeling software to start your project.

3D printing resolution: The bigger the 3D file, the better?

The size of your file is not the only factor when it comes to the 3D printing resolution of your object. For example, Selective Laser Sintering (SLS), SLA or Binder Jetting won’t have the same printing resolution. The 3D printing technology you will choose also has an impact on the overall quality of your print, but the size also matters. 

Same as for regular (2D) printing, the polygon count can be increased or reduced depending on the size of the object your printing. Exporting a 3D file with millions of polygons to print as a five-centimeter object is not worth it. Now if you plan to print an object as big as possible. It might be useful to increase the resolution of the file.

Why you should consider reducing the size of your STL file?

A large 3D file is not a problem, but it can be if you want to share or upload it. If you need to manufacture your part using an online 3D printing service, it is better to get a file easily uploadable. For example, on our 3D printing service, the files you’re using need to weigh less than the maximum of 50MB and every single 3D file shouldn’t exceed 1 million polygons. There is no real limitation in the system, but keep in mind that a big volume can slow all your actions down.

Moreover, when these files are that heavy, details on the objects are sometimes beyond what we can see, or what a 3D printer can actually print. The goal here is not to reduce the size of your part to get lower quality but to get a smaller file with the highest quality possible. With a big file, at best your object will be printed with no visible difference, at worse our system won’t be able to handle the huge file. So even if you’re making the most gorgeous 3D file and push the resolution to its maximum, it won’t necessarily bring you a lot. To keep it under control, at Sculpteo, we’ve established two strong rules and a set of good practices to follow:

  • The first rule is that your 3D file needs to be less than 50MB. 
  • The second rule is that your 3D file needs to contain less than 1 million polygons.

But first, why are these files so large? When exporting 3D models to STL files for additive manufacturing, it is expressed as a mesh, which is made of triangles. Bigger the triangles are, the less detailed the parts will be, but the smaller and the greater the number of triangles is, the smoother the curves of your object’s surface will be! To sum it up, the more triangles, the bigger the size of your file will be. You will have to find the right balance between a detailed 3D model and a non-pixelated object.  

In order to compress your STL file, you will have to find the correct setting in your 3D modeling software, to reduce the size without affecting the printability of your file.

How to reduce your STL file size?

In most 3D modeling software, you will find the option to reduce your file quite easily. In some cases, the program can ask you to set a maximum tolerance for your file: it is actually the maximum distance between the original shape and the STL mesh you need to export. The recommended tolerance is 0,01 millimeters. You can’t set a smaller tolerance, because 3D printers could perceive this level of details. But if you set a bigger one, the triangles might be visible!

Your software might not necessarily offer the possibility to reduce the size of your file. If you are in this case, what are your other options? If your software doesn’t have this particular tool, you can check the free versions of other software featuring this basic tool, such as Meshmixer!

Take care of your STL file before the 3D printing process: here are 3 steps for best STL file resolution, you will find our best advice to get the perfect part. You can also check our article to learn how to edit and repair your STL file with the best STL editors. 


Our online service is also offering great optimization tools to help you identify the weakness of your 3D model, or to optimize your object thanks to hollowing or thickening features for example. If you have any doubt or questions regarding your 3D model, don’t hesitate to contact our sales team.

Are your 3D files ready and reduced? You can now try to upload your file on our website to get your instant quote. You will receive your parts in a few days. 

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