Free Estimating Tool
Conduit Fill Calculator
Calculate minimum conduit trade sizes instantly based on NEC Chapter 9 Tables 4 & 5. Designed for THHN/THWN-2 standard conductors.
Calculator Inputs
4 Wires
1102030
Note: Include equipment grounding conductors in your total wire count per NEC fill rules.
Real-Time Results
Recommended Conduit Size
Calculation ReadyBased on your inputs, here is the minimum required trade size.
2" EMT
Total Conductor Area:1.0716 sq in
Actual Fill Percentage:31.9%
NEC Allowed Fill (4 Wires):40% max
Disclaimer: Sizing is based on standard NEC Chapter 9 Tables. Actual internal dimensions may vary slightly by manufacturer. Always verify local code amendments and exact conduit specs prior to installation.
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Frequently Asked Questions
What is the maximum allowable conduit fill?
According to NEC Chapter 9, Table 1, the allowable fill is 53% for 1 conductor, 31% for 2 conductors, and 40% for over 2 conductors.
Do equipment grounding conductors count toward conduit fill?
Yes, all conductors including equipment grounding conductors, bare or insulated, must be counted when calculating conduit fill according to the NEC.