Calculate conduit fill percentage for EMT, PVC, RMC, and IMC. Supports THHN, THWN, and XHHW wire types with instant NEC compliance check.
Based on NEC Chapter 9 Tables 1, 4, and 5
This calculator provides estimates for reference purposes only. Results must be verified by a licensed electrician or electrical engineer before any installation.
NEC Reference: NEC Chapter 9 Tables 1, 4, and 5
Click a preset to auto-fill, or configure manually below
The NEC limits conduit fill to prevent overheating and allow proper heat dissipation. Fill percentage = total conductor area ÷ conduit internal area.
| Conductors | Max Fill |
|---|---|
| 1 conductor | 53% |
| 2 conductors | 31% |
| 3+ conductors | 40% |
3/4" EMT = 0.533 in² × 40% = 0.213 in² available. Each #12 THHN = 0.0133 in². Result: 16 wires max.
Aim for 35% fill for easier pulls
Required for most commercial installs
360° max between pull points
⚠️ IMPORTANT LEGAL DISCLAIMER
For Reference Only: This calculator is provided for educational and informational purposes only. It is not intended to be a substitute for professional engineering design, advice, or certification.
Code Compliance: Calculations are based on the 2023 National Electrical Code (NEC®). However, local codes, amendments, and Authority Having Jurisdiction (AHJ) requirements vary by location and may supersede standard NEC requirements.
No Liability: SparkShift and its affiliates assume no liability for errors, omissions, or the use/misuse of this tool. Users are solely responsible for verifying all results against applicable codes and standards before installation. Always consult a licensed electrician or engineer.