Measuring arches and radiuses	When measuring arches, three precise measurements must be made. (A)The length of the total arch being inserted, (B)the height of the arch, and (C)the width of the arch. With these measurements, we can calculate the radiuses we need.
HOME	Where an arch is being placed in different corners of an opening, simply measure the length, height and width of the arch as described above. Remember, if you are finishing the arch with sheetrock to subtract that figure from both sides of the arch.
	If your opening is a true arch, then (B) the height, will be half of the (A) length measurement. In this case we are measuring the entire opening as the arch will stretch from one side of the opening to the other.
	In some cases the opening will be larger and the arch more shallow. The measurements are the same, but the total length will be more than half the height measurement. If you need a division, or the arch to form a divider from one room to the next, a measurement X will be needed.