WireFillChart

WireFillChart is a free, browser-based NEC 2023 wire fill chart and conduit fill calculator for US electricians, inspectors, engineers and students. Pick a conduit type (EMT, IMC, RMC, PVC Schedule 40/80, FMC, LFNC, ENT), add THHN, THWN-2, RHH, RHW-2 or TW conductors, and read the live fill percentage, the NEC Chapter 9 Table 1 status (53/31/40% budgets) and a jamming-risk hint; on overfill it recommends the next trade size. The site also has fill charts, box fill, pull box, conduit bend offset, voltage drop and wire size calculators. No signup. Supported by advertising. Reference only: verify against the adopted code and your AHJ. Independent; not affiliated with NFPA.