Try the STL ⇄ OBJ 3D Model Converter
Convert STL ⇄ OBJ and also PLY, OFF, 3MF, AMF and GLB in your browser. Batch convert several files and download a ZIP, fix inch/mm units.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
An OBJ model exported in inches converts to STL with a 25.4 scale factor applied, producing a millimetre-scale STL ready to load directly into a slicer.Open the STL ⇄ OBJ 3D Model Converter
Illustration. Open the tool for the real thing.
What is the STL ⇄ OBJ 3D Model Converter?
STL and OBJ are both triangle-mesh formats, but a lot of CAD, slicer, game and 3D-editing software only accepts one of them. This tool does a real conversion: it parses the triangle and vertex data from your file and rebuilds it in the target format — binary or ASCII STL, OBJ, binary or ASCII PLY, 3MF, AMF, OFF or GLB. Drop in several files at once and you get a list of results with one-click downloads and a ZIP of everything.
Unit and axis options solve the problems that usually follow a conversion: choose the source units (or let the file's own unit be used) and the output units to convert inches to millimetres in the same step, rotate Y-up game assets to Z-up for printing, apply an extra scale factor, and move the part to the print bed. A 3D preview with volume, size and a watertight check lets you verify the result before it reaches your slicer.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
STL (binary/ASCII), OBJ, PLY, 3MF, AMF, OFF and GLB from any supported input.
Convert many files at once and download them together.
Inch/mm/cm/m conversion, Y-up → Z-up and extra scale in the same step.
3D preview with size, volume and watertight status.
AZRS tools are free to open and use.
It opens in your browser, so there is nothing to download.
Used for
Pick one to see how it fits.
Makers whose slicer only accepts STL
Convert an OBJ export from a 3D design tool into STL in one step.
Try it freeAnyone importing a printed model into a 3D editor
Convert STL to OBJ for tools that expect OBJ's vertex/face format.
Try it freePeople fixing a model exported in the wrong units
Apply a real scale factor during conversion instead of rescaling manually in a separate program.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This 3d tool | Desktop software | |
|---|---|---|
| Install | Nothing to install | Usually an app or program to install |
| Account | No signup | Depends on the product |
| Cost | Free to use | Free or paid, depends on the product |
| Where it runs | In your browser tab | On your computer |
Questions people ask
Can I convert many files at once?
Yes — drop several files; each is converted and you can download them individually or as a ZIP.
Does it keep colours and textures?
No — only the mesh geometry is converted; STL cannot store colours and OBJ materials are not carried over.
Can it convert CAD STEP files?
Use the STEP to STL converter; STL to STEP is available too.
Does this actually convert the file, or just rename it?
It genuinely parses the real triangle/vertex data and rebuilds the file in the target format — STL and OBJ store geometry differently, so a rename alone would not work.
Can I convert OBJ to STL and back without losing precision?
Coordinates are carried through as full floating-point values, so there's no meaningful precision loss from the format conversion itself.
More free tools
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Try the STL ⇄ OBJ 3D Model Converter now
Convert STL, OBJ, PLY, 3MF, AMF, GLB — batch, with unit fix. Free to use.
Try it free