How many wires fit in a conduit? Pick the conduit type and trade size for the full NEC fill chart. Internal areas come from NEC Chapter 9, Table 4, conductor areas from Table 5, and the fill percentages from Table 1 — 53% for one conductor, 31% for two, 40% for three or more.
A 1/2-inch EMT conduit holds 9 12 AWG THHN conductors or 12 14 AWG THHN conductors. A 3/4-inch EMT holds 16 12 AWG. A 1-inch EMT holds 26. Remember that a 12/2 cable pulled as loose conductors is three wires — hot, neutral, and ground — and all three count.
Open the conduit fill calculatorThin-wall steel tubing, the most common raceway in commercial interiors and exposed residential work. Joined with set-screw or compression couplings, …
9 × 12 AWG THHN in 1/2-inch · NEC Article 358
Rigid nonmetallic conduit, solvent-welded. The default for underground runs, wet locations, and corrosive environments. Schedule 80 has thicker walls …
8 × 12 AWG THHN in 1/2-inch · NEC Article 352
Heavy-wall threaded steel conduit — the thickest and strongest raceway in the NEC. Used for service masts, hazardous locations, and anywhere physical …
9 × 12 AWG THHN in 1/2-inch · NEC Article 344
Threaded steel conduit with a thinner wall than RMC, so it is lighter and has slightly more internal area. Permitted anywhere RMC is permitted.…
10 × 12 AWG THHN in 1/2-inch · NEC Article 342
| EMT size | 14 AWG | 12 AWG | 10 AWG | 8 AWG | 6 AWG | 4 AWG | 2 AWG | 1/0 AWG |
|---|---|---|---|---|---|---|---|---|
| 1/2" | 12 | 9 | 5 | 3 | 1 | 1 | 1 | — |
| 3/4" | 21 | 16 | 10 | 5 | 4 | 2 | 1 | 1 |
| 1" | 35 | 26 | 16 | 9 | 6 | 4 | 2 | 1 |
| 1-1/4" | 61 | 44 | 28 | 16 | 11 | 7 | 5 | 3 |
| 1-1/2" | 83 | 61 | 38 | 22 | 16 | 9 | 7 | 4 |
| 2" | 138 | 100 | 63 | 36 | 26 | 16 | 11 | 7 |
| 2-1/2" | 241 | 176 | 111 | 64 | 46 | 28 | 20 | 12 |
| 3" | 364 | 266 | 167 | 96 | 69 | 42 | 30 | 19 |
| 3-1/2" | 476 | 347 | 218 | 126 | 91 | 56 | 39 | 24 |
| 4" | 608 | 443 | 279 | 161 | 116 | 71 | 50 | 31 |
Maximum THHN/THWN-2 conductors, all the same size, at the NEC fill limits. For PVC, rigid metal, or IMC see the type pages above.
| Trade size | EMT (in²) | PVC Sch 40 (in²) | Rigid (RMC) (in²) | IMC (in²) |
|---|---|---|---|---|
| 1/2" | 0.122 | 0.114 | 0.125 | 0.137 |
| 3/4" | 0.213 | 0.203 | 0.220 | 0.235 |
| 1" | 0.346 | 0.333 | 0.355 | 0.384 |
| 1-1/4" | 0.598 | 0.581 | 0.610 | 0.659 |
| 1-1/2" | 0.814 | 0.794 | 0.829 | 0.890 |
| 2" | 1.342 | 1.316 | 1.363 | 1.452 |
| 2-1/2" | 2.343 | 1.878 | 1.946 | 2.054 |
| 3" | 3.538 | 2.907 | 3.000 | 3.169 |
| 3-1/2" | 4.618 | 3.895 | 4.004 | 4.234 |
| 4" | 5.901 | 5.022 | 5.153 | 5.452 |
IMC gives the most usable area at every trade size and PVC Schedule 40 the least, because PVC walls are thicker than steel walls of the same trade size. The differences are small but they change the answer at the margin.
A raceway can pass the fill calculation and still be wrong. Three further rules apply to almost every real pull: