Conduit Fill Calculator
Check conduit fill against NEC limits. Choose your conduit type and trade size, add conductors, and WireCoder computes the actual fill percentage and flags over-fill instantly.
How it works
Fill is the total conductor area (NEC Chapter 9, Table 5) divided by the conduit interior area (Table 4). The NEC allowable fill is 53% for one conductor, 31% for two, and 40% for three or more (Table 1).
Frequently asked questions
What is the maximum conduit fill?
Per NEC Chapter 9, Table 1: 53% for 1 conductor, 31% for 2, and 40% for 3 or more conductors.
Which conduit types are supported?
EMT, RMC, IMC, PVC Schedule 40, and PVC Schedule 80, trade sizes 1/2" through 4".