How do I find the length of an arc?

Shouldn’t it be listed in “what”.

type length

It has to be calculated. It’s not part of the NURBS definition.
Piotr is right, use the Length command.

Thanks. But it seems to me the length of a curve/line should be an ESSENTIAL bit of info that should be in the “What” results. How hard would it be to include the “Length” code as part of What?

The What command was never intended to provide information useful to a user. It was intended to provide NURBS specific information and it does that. It is the “raw” information that can be used to calculate more user friendly information like what the Length command does.

I’m not defending it, I’m trying to explain why it is what it is.

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I’m a “user” and I frequently use the What command to find out the degree of a curve, whether has uniform or non-uniform knots, the number of control points, etc. which can all be useful information for this “user”.

I have never expected the What command to provide the length of a curve. That is what the Length command does.

Check out Bubble from


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In my ignorance, I assumed “What” was similar to “List” in AutoCAD. I also was taught by certified Rhino instructor in Rhino class to use What for object information like Radius. So based on that, I expected it to provide length. My mistake. Still, seems pretty inefficient to have to use “length” to find the length of an arc, and “what” or some other command for the radius or other info.

You can even use List if you want as well! for geek level information.


That gives length AND radius. Generally the only info I need. Thanks.

As I recall the List command was added just for that reason.
Back in those days, many AutoCAD users were adding Rhino to their tool bag so the List command was added.
If memory serves, you can thank Mary F. for that one.

List, not What, appears to be command not intended to provide information for users.

What could give curve length, it seems to me, without creeping into too-much-info-to-be-useful terrritory. That seems to be reasonable basic info for a curve object.


So you pretty much agree but you didn’t create a YouTrack item to be added to the Arc of the Covenant warehouse of requests?

I’m so so glad you are there keeping track and making sure I do things when it’s convenient for you.


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