Size and units Video walkthrough 1:23
Fix STL units in CADFormats
Follow the video to assign inches, convert to millimetres, and export the sample model as a unit-aware 3MF in CADFormats.
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The walkthrough uses supplied examples. You can follow along before choosing your own file.
This video tutorial shows where to assign and convert units in the CADFormats Size and units workspace. Follow along with the supplied one-unit model, then export a 3MF that records the intended unit.
An STL stores coordinates without a unit label. If the same part opens at a different size in another application, establish what those coordinates were intended to mean before resizing the geometry. You need a known dimension or the export unit from the source application; the file alone cannot recover it.
Open and check the model
Open Size and units in the Workbench. Choose your STL, or use the supplied unitless example from Examples to follow the video. Check the dimensions in Model details.
The video uses a one-unit example. Treating that width as one inch means a physical width of 25.4 mm. This is a demonstration, not a recommendation to assume every STL is in inches.
Assign the intended unit
Choose Interpret coordinates as a unit, then select the unit that the existing coordinates represent. In the video, that is inches. Preview the assignment, then apply it only if it matches what you know about the source part.
Assigning a unit gives the existing numbers a meaning. It does not rescale those coordinates.
Convert to the output unit
Choose Convert units, keep physical size and select millimetres. Preview the result and check the dimensions. Converting inches to millimetres changes the coordinate numbers while keeping the same physical size.
The preview can be discarded. Apply it when the dimensions and interpretation are correct. If the part itself needs to become larger or smaller, follow the resizing walkthrough instead.
Verify and export
Select 3MF, then Verify and export. Download the checked result. This exporter records millimetres in the 3MF file, so the intended unit accompanies the model.
If you choose STL, it will still have no unit label. Use the intended unit when importing it into your next application, and check a known dimension there. Keep the original source file so you can revisit the interpretation.