Conduit Fill Calculator
Calculate conduit fill percentage and verify NEC compliance for electrical installations. Determine how many wires can safely fit in a conduit.
Calculate Conduit Fill
Fill Calculation Results
Conduit Area
0.533 in²
3/4" EMT
Total Wire Area
0.0399 in²
3 × 12 AWG THHN
Fill Percentage
7.5%
Max allowed: 40% (3+ wires)
✓ NEC Compliant - This configuration meets code requirements
Maximum wires of this size that fit: 16
NEC Conduit Fill Requirements
1 Wire
53% maximum fill
2 Wires
31% maximum fill
3+ Wires
40% maximum fill
What is Conduit Fill?
Conduit fill refers to the percentage of a conduit's internal area occupied by electrical wires. The National Electrical Code (NEC) limits conduit fill to prevent overheating and allow for easy wire pulling during installation. Proper conduit sizing ensures safe and code-compliant electrical installations.
Why Fill Limits Matter
- • Prevents wire overheating
- • Allows easier wire pulling
- • Reduces insulation damage risk
- • Ensures NEC code compliance
- • Extends wire lifespan