How to Reduce STL File Size for 3D Printing


Reducing the size of an STL file for 3D printing is a useful step to make 3D printing easier and faster. Many people wonder how exactly to reduce the file size of an STL so I decided to write this article detailing how to do this.

To reduce the STL file size for 3D printing, you can use online resources like 3DLess or Aspose to do this by importing the STL file and compressing the file. You can also use software like Fusion 360, Blender and Meshmixer to reduce STL file sizes in a few steps. It does result in a lower quality file for 3D printing.

Keep on reading for more information about reducing STL file size for 3D printing.

How to Reduce STL File Size Online

There are many online resources that can help reduce the size of your STL file.

How to Reduce STL File Size with 3DLess

3DLess is a user-friendly website that allows you to reduce the size of your STL file using a few simple steps:

  1. Click on Choose File and select your file.
  2. Reduce the number of vertices in your model. You can see a preview of how your model will look when you scroll down on the website.
  3. Click on Save To File and your newly reduced STL file will be downloaded on your computer.

How to Reduce STL File Size for 3D Printing 3dless

How to Reduce STL File Size with Aspose

Aspose is another online resource that can reduce STL files, as well as offering a number of other online services.

Use the following steps to compress your file:

  1. Drag and drop or Upload your file in the white rectangle.
  2. Click on the Compress Now green bottom at the bottom of the page.
  3. Download the compressed file by pressing on the Download Now button, which appears after the file has been compressed.

How to Reduce STL File Size for 3D Printing - Aspose

Unlike 3DLess, on Aspose you can’t select the number of vertices you want your model to have after reduction, or any criteria for file size reduction. Instead, the website automatically chooses the reduction amount.

How to Reduce STL File Size in Fusion 360

There are 2 ways to reduce the size of an STL file – Reduce and Remesh – both of them using Mesh tools. Firstly, to open an STL file go to File > Open and click on Open From My Computer, then select your file. The steps to reduce the size of the file are as follows:

Reduce File Size with “Reduce”

  1. Go to the Mesh category, at the top of the workspace, and select Reduce. This has a fairly straightforward way of operating: it reduces the file size by diminishing the faces on the model.

How to Reduce STL File Size for 3D Printing - Fusion 360 Reduce

There are 3 types of reduction:

  • Tolerance: this type of reduction reduces the number of polygons by merging faces together. This will cause some deviation from the original 3D model, and the maximum amount of deviation permitted can be adjusted using the Tolerance slider.

How to Reduce STL File Size for 3D Printing - Fusion 360 Reduce Option 2

  • Proportion: this reduces the number of faces to a proportion of the original number. As with Tolerance, you can set this proportion using the slider.

The Proportion type also has 2 Remesh choices:

  • Adaptive
  • Uniform

Basically, adaptive remeshing means that the shape of the faces will adapt to the model more, meaning that they will preserve more detail, but they won’t be consistent throughout the model, while Uniform means that the faces remain consistent and have a similar size.

How to Reduce STL File Size for 3D Printing - Fusion 360 Reduce Option 1

  • Face Count: this type allows you to put a number of faces that you want your model to be reduced to. Again, there are the Adaptive and Uniform remesh types that you can choose from.

How to Reduce STL File Size for 3D Printing - Fusion 360 Reduce Option 3

  • Click OK to apply the changes to your model.
  • Go to File > Export and select the name and location of your reduced STL.

Reduce File Size with “Remesh”

This tool can also be used for reducing the STL file size. Once you click on it, a Remesh pop-up window will appear on the right side of the viewport, giving you a number of options.

How to Reduce STL File Size for 3D Printing - Fusion 360 Remesh

Firstly, there is the Type of Remesh – Adaptive or Uniform – which we discussed above.

Secondly, we have the Density. The lower this is, the lower the file size will be. 1 is the Density of the base model, so you will want to have values below 1 if you want your file to be smaller.

Next, Shape Preservation, which refers to the amount of the original model you want to preserve. You can alter this with the slider, so try different values and see which works for you.

Finally, you have three boxes you can tick:

  • Preserve Sharp Edges
  • Preserve Boundaries
  • Preview

Check the first two if you want your remeshed model to be as close to the original as possible, and check the Preview box to see the effect of your changes live on the model, before actually applying them. You can do some experimenting to see what works for your particular model and goal.

Don’t forget to click OK to apply the changes, and then go to File > Export and save your file in the preferred location.

How to Reduce STL File Size in Blender

Blender supports STL files, so to open your model, you have to go to File > Import > STL and select your file. Follow the steps below to reduce your fie size:

  • Go to Modifier Properties (the wrench icon on the right side of the viewport) and click on Add Modifier.

How to Reduce STL File Size for 3D Printing - Blender Add Modifier

  • Select Decimate. This is a modifier (or procedural operation) that reduces the geometry’s density, meaning it will reduce the number of polygons in the model.

How to Reduce STL File Size for 3D Printing - Blender Decimate

  • Reduce the Ratio. By default, the Ratio is set at 1, so you will have to go below 1 to diminish the number of faces.

How to Reduce STL File Size for 3D Printing - Blender before changing the ratio

Notice how fewer faces mean less detail on the model. Always try to find a value that allows for your model to be reduced without compromising too much on quality.

How to Reduce STL File Size for 3D Printing - Blender after changing the ratio

  • Go to File > Export > STL and choose a name and location for the file.

Here is a video that shows the process.

How to Reduce STL File Size in Meshmixer

Meshmixer also allows you to import, reduce and export STL files. Although slower than Blender, it does offer more options when it comes to simplifying 3D models.

Meshmixer operates similarly to Fusion 360 in terms of reduction options. To make an STL file smaller, follow these steps:

  • Press CTRL + A (Command+A for Mac) to select the entire model. A pop-up window will appear in the top-left corner of the viewport. Select on the first option, Edit.

How to Reduce STL File Size for 3D Printing - Meshmixer Edit

  • Click on Reduce. Once the command is computed, a new pop-up window will appear. Once you select the entire model, you can use the shortcut Shift+R to open the Reduce pop-up window.

How to Reduce STL File Size for 3D Printing - Meshmixer Reduce

Let’s go through the options you have for reducing the size of the model. The two main selections you can make here are the Reduce Target and Reduce Type.

The Reduce Target selection basically refers to the aim of your file reduction operation. There are 3 reduction choices you have:

  • Percentage: reduce the number of triangles to a specific percentage of the original count. You can adjust the fraction using the Percentage slider.
  • Triangle Budget: reduce the number of triangles to a specific count. You can adjust the count using the Tri Count slider.
  • Max Deviation: reduce the number of triangles as much as possible, without going over a Maximum Deviation which you can set using the slider. The “deviation” refers to the distance that the reduced surface deviates from the original surface.

How to Reduce STL File Size for 3D Printing - Meshmixer Reduce Window

The Reduce Type operation refers to the shape of the resulted triangles and has 2 options to choose from:

  • Uniform: this means that the resulted triangles will have equal sides as much as possible.
  • Shape Preserving: this option will aim to make the new shape as similar as possible with the original model, disregarding the shapes of the new triangles.

Lastly, there are two checkboxes at the bottom of the pop-up window: Preserve Boundaries and Preserve Group Boundaries. Checking these boxes usually means that your model’s borders will be as accurately preserved as possible, even without them checked Meshmixer attempts to preserve the borders.

  • Go to File > Export and choose the location and the format of the file.

What is the Average File Size of an STL File in 3D Printing

The average file size of an STL for 3D printing is 10-20MB. The 3D Benchy, which is the most common 3D printed object is around 11MB. For models with more detail such has miniatures, statues, busts, or figures, these can average at around 30-45MB. For very basic objects these are mostly under 1MB.

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