how do you convert a square to a circle

I am trying to find out what a square turns into a circle. I work in a tubemill factory and I am trying to determine say a 1.5 inch round tube and once it is squeezed into square what size it will be. Is there a formula for this. For the 1.5 square the round tube is 1.9 but I want to know what formula. is used thanks

I am trying to find out what a square turns into a circle. I work in a tubemill factory and I am trying to determine say a 1.5 inch round tube and once it is squeezed into square what size it will be. Is there a formula for this. For the 1.5 square the round tube is 1.9 but I want to know what formula. is used thanks

I suppose when squeezing your tube into square the circumference of the initial circle is equal to the perimeter of the square. The formula for the circumference is pi*d, where d is the diameter and pi = 3.14159. The perimeter of a square is 4 times is side.

So pi*d = 4*a, thus d = 4*a/pi = a * 4/3.14159 = a * 1.2732

Checking for a = 1.5, d = 1.5 * 1.2732 = 1.91. So your figures comply to the formula. :)

Again, here it is: d = a * 1.2732. Or a = d * 0.785