Understanding Field Math
Field math covers the everyday geometry calculations behind conduit and box work: finding area, finding volume, and checking how full a space is relative to its total capacity.
Conduit area
A conduit's cross-sectional area comes from its internal diameter, using the standard circle area formula. This is the starting point for any fill calculation.
Box volume
A box's volume comes from multiplying its length, width, and depth. Like conduit area, this is a starting measurement rather than a finished compliance check.
Fill percentage
Fill percentage compares an occupied area to a total area. These calculators report the raw percentage from the numbers you provide — they don't apply code-based fill limits, conductor area tables, or box-fill allowances. For code compliance, consult the applicable electrical code directly.