Input Parameters
About This Calculator
- NEC Ch.9: ≤40% for 3+ wires
- ≤31% for 2 wires, ≤53% for 1 wire
- Based on EMT conduit areas
How this conduit fill calculator works
Fill percentage = total wire area / conduit area × 100. Wire areas from NEC Table 5 (THHN).
NEC limits: 53% for 1 wire, 31% for 2 wires, 40% for 3+ wires in the same conduit.
FAQ
Max conduit fill?
40% for 3+ wires per NEC Chapter 9.
How to calculate?
Wire area sum ÷ conduit area × 100%.
3/4" EMT capacity?
~4× #12 or 3× #10 THHN at 40% fill.