How long is a 40 inch umbrella?

[Bunyip]

OK, stop laughing and listen a second.

My 34 inch umbrella is 23 inches long when closed. That means it easily fits into my luggage. I'd like to know how long the shaft of a 40 inch umbrella is because I'd like to know if that too would fit my luggage.

And if you know where I can find a 40 inch white umbrella with removable backing (to turn it into a shoot-through) please let me know.

[I @ M]

Most of the "40 inch" type measurements are done like televisions and monitors, ie. the diagonal measurement but that really doesn't help cos some umbrellas have 2 or 3 stage collapsible "handles" .

Pythagoras is your friend if you know a few basic measurements from the gear on offer. :D