Bend calculator: Just punch in your measurement and it will give you the multiplier where you need to bend. Its good for offsets, 3 point saddles and stub bends.
Rolling offset: This page is used to calculate rolling offsets. You need to find the height of the offset(Y) and then the distance of how far it is rolling(X). After (Z) is calculated take the (Z) calculation and go to the bend multipliers page. Plug in the (Z) calculated number into one of the bend multipliers spots(10, 22, 30, 45, 60 degrees).