I was trying to locate via google a formula on how to find the cut length of a piece of angle has to be before it is rolled. I have a rolled piece of sheet metal on the inside of the angle and the length difference is around 2". I am guessing that there is a neutral line somewhere on the angle, I just want to make sure that it is calling out the correct length.

SWX sheet metal does a great job of calculating flat patterns IF you give it accurate information to work with. Material thickness is the worst offender as many folks make the mistake of using published values for material thickness instead of verified measured thickness. If the inside bend radius is more than 2.5 times the material thickness then you could use a k-factor of .5 and get a pretty darn accurate flat pattern. If the IBR is less than that then you will need to get some better information on the parameters affecting the operation. If the part is truly rolled then its IBR is most likely many times the material thickness.