Import *.STL files at their true scale size in BLENDER

Blender imports STL files at a 0.001 scale because the STL file format does not specify units. This means that the size of an object in an STL file is arbitrary, and it is up to the software that is importing the file to determine the scale. Blender, by default, imports STL files as if they are in meters, which means that a 1 unit cube in an STL file will be imported into Blender as a 1 meter cube. To import an STL file at a different scale, you can use the "Scale" option in the import dialog.
Here are the steps on how to import STL scales into Blender:
Open Blender.
Go to File - Import - STL.
In the Import STL dialog, select the STL file that you want to import.
In the Scale section, enter the scale factor that you want to use. For example, to import the STL file at a scale of 1 millimeter, enter 0.001.
Click Import.
The STL file will be imported into Blender at the specified scale.
Here are some additional things to keep in mind when importing STL files into Blender:
The units that you use in Blender will affect the scale of the imported STL file. If you have set the units in Blender to millimeters, then the imported STL file will be scaled by a factor of 1000.
If you are importing an STL file for 3D printing, you will need to make sure that the scale is correct. Most 3D printers use millimeters, so you will need to scale the STL file by a factor of 1000 if you have set the units in Blender to meters.
You can also use the "Transform" tool in Blender to scale the imported STL file after it has been imported.
3D model used for the case study available at:
www.artec3d.com/3d-models/cop...

[@simo92apple]

Thank you!

[@3DComparison]

Thank you very much for your comment! Glad you find the video useful!

[@JHinterl]

🥰thank you very much, that's exactly what I just haven't understood so far, why it's always scaled incorrectly in Blender.

[@3DComparison]

Glad it helped!

[@3DComparison]

Did you ever wondered why objects are not imported at scale? Let me know in the comment section!

[@maartenvd84]

Thanks 🙏

[@3DComparison]

You’re welcome 😊

[@raywong171]

Thanks! Very helpful. But what if we were just given an stl file and didn’t have the original measurements to work with? Is there a way that we can ensure it was imported in the right dimensions? Or check it in some other app or program? Still very new to 3d modelling so sorry if it’s a stupid question m. Thanks

[@3DComparison]

Hello! That is a very good question! STL files do not store units of measurement, so the dimensions of the file will be in whatever units you choose when you import it into a 3D software. Usually CAD software such as CATIA/SolidWorks/Fusion 360 will import by default using the mm units (if these haven't been changed). As presented within the video Blender will import them as meters since this is the default measuring unit set. The vast majority of 3D scanning solutions will also make use of mm as the default measurement unit so it's a good practice to start with mm and afterwards measure and analyze. Other software such as photogrammetry will generate the 3D models at a generic value, and afterwards with the software the user needs to calibrate the 3D mesh to bring it to their truescale before having the STL file exported. Thanks for the comment, if you have any other questions feel free to add a comment and I will gladly reply.

[@raywong171]

@@3DComparison thanks for the reply! That's great info again

[@rj_enoz]

Thank for the tutorial~
I got a Question,
If u export do u have to change it back for 3D printing it???

[@3DComparison]

That's a great question! I will create a video tomorrow regarding this!

[@bialaSto]

​@@3DComparisonHave you made a video about the question?

[@d_wib3810]

My import window doesn't show option for scale, it reads Clamp. How can I have the scale window at import? Thanks!!!

[@3DComparison]

Hello, I am curios what version of Blender are you using. I have the scale option available both in 3.6.4 as well as in Blender 4.0.2. Keep in mind that there are two STL import options. One is simple stl (.stl) and one is stl (.stl - experimental). For both version I have the import windows by default. I would suggest that you do a fresh install of the latest 4.0.2 version!

[@d_wib3810]

@@3DComparison Hello, I downloaded it on monday for the first time. I just realized I was importing an OBJ file not STL. So maybe that makes a difference?

[@3DComparison]

Yes, that would be the difference.

[@d_wib3810]

Thank you!@@3DComparison