Conduit Fill
Add up cable cross-sectional areas and compare them with the conduit inner area. You set the fill limit — 40% is only a starting number. The result shows fill percent, both areas, and whether you are over the limit you typed. It is not an NEC compliance check and not electrical advice.
Frequently asked questions
How is fill percent calculated?
Each cable area is π(d/2)² using the outside diameter. Fill percent is the sum of those areas divided by the conduit inner area, times 100. Every diameter must use the same unit. Counts are whole numbers of identical cables.
Is this an NEC compliance check?
No. This is not an NEC compliance check and not electrical advice. It only compares your cable area with the conduit area and the limit you typed. It does not apply chapter 9 tables, jam ratios or installation rules.
Why does the limit start at 40%?
40 is a blank starting number so the field is not empty. Change it to whatever you want to compare against. Crossing that number is only your comparison — the tool does not decide that a fill is acceptable or unacceptable under any code.