Need help scaling by length - Rhino 5

Hey all!

I need to create standardized sizes of closed ellipses. It’s for bracelet sizing but it’s good to know how to do this either way.

I have standard length sizes I need, and I need to scale the same ellipse up proportionally to different total lengths (circumference). Is there an obvious command I am just not aware of or is this a legit question?

Again, I need to scale closed and/or open curves to a specific length/circumference.

Thanks in advance! lol

I’m not aware of a way to do that using the native tools in V5.

Potentially a Grasshopper tool could be written in the Beta Grasshopper plug-in, but that isn’t something I can do.

Hello- see how this works - (719 Bytes)

To use the Python script use RunPythonScript, or a macro:

_-RunPythonScript "Full path to py file inside double-quotes"


1 Like

While calculating the circumference of an elllipse is not a simple task, if you scale it maintaining the ratio of the major and minor axes then the circumference scales proportionately to the length.

Thus you can scale3d your ellipse by desired circumference / current circuference.


You are a life saver. This worked perfectly! Thank you so much!