WireWicket / Field calculation 01
Raceway fill calculator
Check repeated THHN / THWN-2 conductors against an EMT, RMC, PVC Schedule 40, or PVC Schedule 80 trade size. The permitted fill changes with conductor count.
Calculation inputs
Enter a whole number from 1 to 1,000.
This calculator models repeated conductors of one selected size in one selected raceway.
Raceway result
- Total conductor area
- 0.0399 in²
- Allowable conductor area
- 0.2132 in²
- Calculated fill percentage
- 7.5%
3 × 0.0133 in² per conductor
40% of 0.5330 in² EMT area
Total conductor area ÷ selected raceway internal area × 100
NEC references
Chapter 9, Table 1 (permitted fill); Table 4 (EMT raceway area); Table 5 (THHN / THWN-2 conductor area); Article 358 (EMT).
Edition check required
Reference values use NFPA 70 (NEC) 2026. Verify the edition adopted by your jurisdiction and any local amendments. This reference tool does not replace project review or AHJ requirements.
View NFPA 70 (2026) in NFPA LiNK