The arch calculator calculates the distance between the focus points (F) and the arch's center (C). This distance is calculated based on the arch's height and width. Using the diagram below as a reference, the arch's height is represented as distance (H). The arch's width is represented as distance (K). Distance (E) is equal to distance (D). Points represented as (F), represent the foci of the arch.
This calculator will not allow the height (H) to be greater than 1/2half the arch's width (K). However, the height (H) can be equal to 1/2 of the width (K). The result is a perfect circle with a radius of (H) and a diameter of (K).
For details on how to use these calculations to create the shape of the arch and built it, refer to the How to Build an Archway section.