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Conduit Fill Calculator

NEC Chapter 9 · Table 1 & Table 4

When to use: Required any time you install conductors in conduit. NEC Chapter 9, Table 1 limits fill to 53% for 1 conductor, 31% for 2, and 40% for 3 or more. Overfilling damages insulation during pulling and causes heat buildup. Use this calculator during conduit system design to verify compliance and select the correct conduit size before installation.

Conduit

Type

Trade Size (in)

Internal area: 0.864 in²

Conductors

Type

Gauge

Qty

✓ PASS — Within Limit

4.6%

Fill (40% max for 3 conductors)

0%40% limit100%

Summary

Conduit Type & SizeEMT 1"

Total Conductors3

Total Wire Area0.0399 in²

Conduit Internal Area0.864 in²

Available Area (at limit)0.3456 in²

Remaining Capacity0.3057 in²

NEC Fill Limits (Table 1)

1 conductor53%

2 conductors31%

3+ conductors40%