Conduit fill and size checker
After you pick wire for an inlet or battery run, find the smallest conduit it fits. List every conductor, including the equipment grounding conductor and any neutral, because all of them count toward fill.
Basis
2023 NEC Chapter 9. Table 1 limits fill to 53% for one conductor, 31% for two and 40% for more than two. Conduit internal areas are from Table 4 (EMT Article 358, rigid RMC Article 344, PVC Schedule 40 Article 352, flexible metal FMC Article 348). Conductor areas are from Table 5 for THHN/THWN/THWN-2 and XHHW; other insulation types have different areas and are not offered. Table 4 areas are for conduit only; other raceways (PVC Schedule 80, LFNC, ENT) differ. Conduit nipples of 24 in or less may use 60% fill (Chapter 9 Note 4); this tool does not apply that. Results use the stricter normal limit.