Rhino 3dm file version converter

This utility makes use of Rhino3dm.NET, which is licensed under the MIT license. Therefore no Rhino installation is required and 3dm files from Rhino 2-8 are supported.


Rh3dmConverter.zip (7.5 MB)



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One Warning - From my testing.

Do not attempt to convert files “in place”.
Meaning this converter will not overwrite the original file after conversion.
You have to use another directory or another file name.
In fact, if you attempt to convert a file “in place”, you will delete the old file.

will fix.


Nice job, works perfectly so far. Thank you.

popping in to say this works wonderfully, saved me from keep having to chase down folks to ask them to send me a different file version

A must -have software, thanks for sharing , Andrea

You’re a genius, thank you!

How safe is it to use this software?

Perfectly safe.
Save as - and use a different filename.
Your original file remains untouched, and you get a new file.
Doesn’t get any safer.


this converter would be super useful for me. Unfortunately when I hit the browse button to find a file to convert I receive the following error message:


any ideas?

Many thanks,


Download Rhino3dmIO.dll and place it in the same folder as the executable. @john11

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Wonderful, thanks Farouk!

Glad I could help.

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Does this work on Mac?

hi i accidentaly overwrite the file in same place and the files deleted itself and not even in the recycle is there a way i can recover the files

Hi Patrick,
Look for a .bak or .3dmbak file in your directory, with the same filename.
Simply replace the 3dmbak extension with .3dm and you should have your previous version back.

Otherwise, look to your backup, or to your email, if the file went through your email system.
Sending files to yourself is a quick way to provide a failsafe redundancy.

Thanks @gankeyu. This utility is very helpful because of the dialog.

There is a second utility available on Food4Rhino called Convert3DM.
It has been update for Rhino 8, and runs on Windows or Mac.

However, Convert3DM is only for those that are comfortable using Windows and Mac terminal.

If you are not then @gankeyu utility available above is best for you.

Mary Ann Fugier


Saved my bacon. trialled Rhino 8 and built a model in there and it expired. couldn’t open in 6. then I found this. thank you!

Worked perfectly. Thank you very much!