How to scale a 3D model and export it as STL
Scale a model by percent or to a target size in STL Viewer, convert inches to millimeters and save the result as a new binary STL for your slicer.
Scale & export resizes a model and saves it as a new binary STL that you can send to your slicer or share. Use it to print a model smaller or bigger, to fit a part to a size you measured, or to turn a model drawn in inches into millimeters. It is a Premium tool.
Scale and save a model
- Open the model and tap Scale & export in the tools.
- Choose how to scale:
- By percent: enter a scale such as 50 % or 150 %. All three sides change together.
- To a size: pick the Side (width, depth or height) and enter the size you want. The other sides follow in proportion, so the model never gets distorted.
- Check Units in the exported file. Most slicers expect millimeters.
- Read the Exported size to confirm the result.
- Tap Export STL, choose a folder and a file name, and save. Then tap Share if you want to send the file to another app.
Convert inches to millimeters
A model drawn in inches but saved as STL shows up about 25 times too small in most slicers, because STL has no unit. To fix it for good:
- In Model info, set the File units of the model to inches. The size now looks right.
- Open Scale & export, keep the scale at 100 % and set the units in the exported file to millimeters.
- Export. The new STL has the right size in any slicer.
Good to know
- The export always uses the full model, even when a very large mesh is shown as a simplified view.
- The original file is never changed. The export can't replace the model it is made from, so save it under a new name.
- The result is always binary STL, the most compact form of STL. Colors aren't kept, because STL stores none.
- If the app says the scale is out of range, the size you entered is too far from the current one. Enter a value closer to it.
Not sure of the target size? Measure the part that has to fit first, then scale the model to that size along the same side.
Premium
Scale & export is part of Premium, a one-time purchase or a yearly subscription that also unlocks Measure, Section and Compare and removes ads.
Read more about fixing STL files drawn in inches.
Learn more on the blog
- STL Inches to mm: Fix a Model That Prints Too Small or Too Big
- Scale STL to an Exact Size and Measure It (Worked Example)
Questions and answers
Does exporting change my original file?
No. The scaled model is saved as a new binary STL. The export can't overwrite the file it is made from.
Can I scale only one side?
No. When you scale to a size, you choose one side and the other two follow in proportion, so the model keeps its shape.
Can I export to OBJ or 3MF?
No. Scale & export always saves a binary STL, which every slicer can open.
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