Conduit FillCalculator
Estimate raceway fill for common THHN/THWN-2 conductor groupings before you finalize conduit size and layout.
Estimate conduit fill for common THHN/THWN-2 conductor groupings using standard single-conductor areas and the familiar NEC Chapter 9 fill limits: 53% for one conductor, 31% for two, and 40% for three or more. Verify compact-stranded cable dimensions, cable assemblies, nipples, and any manufacturer-specific data before issuing final drawings or installing material.
Conduit Inputs
common THHN/THWN-2 conductors in a selected raceway
Phase / hot conductors
Identical insulated conductors in the same raceway
Neutral conductors
Identical insulated conductors in the same raceway
Equipment grounding conductors
Identical insulated conductors in the same raceway
Fill Summary
Area-based raceway check
EMT 1" is at 123.2% of the allowable fill area for 5 conductors.
Conductor breakdown
Raceway sizes
- This tool assumes individual THHN/THWN-2 insulated conductors, not multiconductor cable, MC cable, or manufacturer-specific compact cable dimensions.
- Raceway fill is only one check. Final design still needs ampacity, temperature correction, bundling, termination, and pulling-tension review.
- Very short nipples and special conditions can use different NEC rules. Treat this as a planning and coordination tool, not automatic approval.
AC Voltage Drop Calculator
Check how your final conductor and route choice affects AC feeder and branch-circuit drop.
DC Voltage Drop Calculator
Use the DC workflow for battery, controls, telecom, and solar homerun checks.
Wire Size Calculator
Move from raceway planning to actual conductor sizing with voltage-drop targets.
Wire Tables
Compare common AWG and kcmil conductor sizes before you lock the conduit layout.
NEC Standards
Review code context for ampacity, raceway fill, and installation assumptions.