Electrical Planning
Conduit Fill Calculator
Check NEC 2026 conduit fill with mixed wire sizes, brand OD seed data, custom cable diameter, and Cat6 planning rows.
NEC 2026mixed wireSouthwireBeldenCat6RomexExcelchart
NEC 2026 / Generic NEC chart
Rows
40% fill chart
Maximum same-size cable counts by conduit size.
| Cable | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" |
|---|---|---|---|---|---|---|---|---|
| 14 AWG THHN | 12 | 21 | 35 | 61 | 83 | 138 | 197 | 304 |
| 12 AWG THHN | 9 | 16 | 25 | 44 | 61 | 100 | 143 | 222 |
| 10 AWG THHN | 5 | 10 | 16 | 28 | 38 | 63 | 90 | 140 |
| 8 AWG THHN | 3 | 5 | 9 | 16 | 22 | 36 | 52 | 80 |
| 6 AWG THHN | 2 | 4 | 6 | 11 | 16 | 26 | 37 | 58 |
| 4 AWG THHN | 1 | 2 | 4 | 7 | 9 | 16 | 23 | 35 |
| 2 AWG THHN | 1 | 1 | 2 | 5 | 7 | 11 | 16 | 25 |
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