Professional electrical conduit fill calculator for electricians and contractors. Calculate conduit fill percentage, verify NEC compliance, and determine maximum number of wires for EMT and RMC conduit types. Supports THHN wire from 14 AWG to 4/0 AWG. Ensure your electrical installations meet National Electrical Code standards for safe and compliant wiring.
Select your conduit type and size (EMT or RMC), choose your wire gauge (THHN conductor from 14 AWG to 4/0 AWG), enter the number of conductors, and click Calculate. The calculator instantly shows fill percentage, NEC compliance status, and whether your configuration meets code requirements for electrical installations.
Enter your conduit and conductor configuration, then click Calculate to see results.
Always follow NEC Chapter 9, Table 1 for conduit fill calculations. Maximum fill percentages vary based on number of conductors: 53% for one conductor, 31% for two conductors, and 40% for three or more conductors.
When installing more than three current-carrying conductors in a conduit, apply appropriate derating factors per NEC 310.15(C)(1). Consider ambient temperature and installation conditions.
EMT (Electrical Metallic Tubing) is lighter and easier to install. RMC (Rigid Metal Conduit) provides superior protection and is required for certain applications. Choose based on your installation requirements.
Never exceed maximum fill percentages. Overfilled conduits can cause wire damage, overheating, and code violations. Always verify calculations with current NEC standards and local codes.