A (simple?) maths question

[PiKe]

I'm trying to work out whether an object will fit up a staircase with a 90 degree corner in it.

What would the minimum width of a staircase have to be in order to manoeuvre a 24 inch square object around a right angled corner? The solution is probably very simple but I can't figure it out.

 

[PiKe]

Very small... 2ft is tiny!

But in order to rotate the object? Is it just half again?

 

[PiKe]

I am of course being thick whilst at the same time overthinking the question. Obviously the answer is 24 inches because there's no real requirement to rotate the item on the corner if it's square! Doh!