Construction & DIY
Conduit Fill Calculator
Calculate the allowable wire fill for electrical conduits according to NEC standards. Mix and match wire sizes to see if they safely fit.
Conduit & Wire Setup
NEC Chapter 9 Rules
Allowable Fill Limits:
- 1 Wire: Max 53% Fill
- 2 Wires: Max 31% Fill
- 3+ Wires: Max 40% Fill
Jamming Warning: When pulling 3 conductors or cables into a raceway, if the ratio of the raceway inside diameter to the conductor outside diameter is between 2.8 and 3.2, jamming can occur. Always leave breathing room for heat dissipation.
Wire Insulation
THHN / THWN-2 Data Used
Fill Results
Conduit Fill Percentage
0.00%
Awaiting Data
Total Wires Count
0
Applicable NEC Fill Limit
0%
Total Wire Area
0.000 sq in
Conduit Total Area (100%)
0.000 sq in
Cross-Sectional Area Usage
Max Limit
Enter wires to see visual fill