NEC 2026
RMC Conduit Fill Chart
RMC (rigid metal conduit, NEC Article 344) is the heavy-wall threaded steel conduit. The tables show the most wires that fit in each trade size at the NEC 2026 fill limit.
Updated
For reference only. Always verify with the NEC edition adopted by your AHJ.
RMC fill: THHN / THWN-2
| Wire size | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" | 5" | 6" |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| #14 | 13 | 22 | 36 | 63 | 85 | 140 | 200 | 309 | 412 | 531 | 833 | 1202 |
| #12 | 9 | 16 | 26 | 46 | 62 | 102 | 146 | 225 | 301 | 387 | 608 | 877 |
| #10 | 6 | 10 | 17 | 29 | 39 | 64 | 92 | 142 | 189 | 244 | 383 | 552 |
| #8 | 3 | 6 | 9 | 16 | 22 | 37 | 53 | 82 | 109 | 140 | 221 | 318 |
| #6 | 1 | 4 | 7 | 12 | 16 | 27 | 38 | 59 | 79 | 101 | 159 | 230 |
| #4 | 1 | 2 | 4 | 7 | 10 | 16 | 23 | 36 | 48 | 62 | 98 | 141 |
| #3 | 1 | 1 | 3 | 6 | 8 | 14 | 20 | 31 | 41 | 53 | 83 | 120 |
| #2 | 1 | 1 | 3 | 5 | 7 | 11 | 17 | 26 | 34 | 44 | 70 | 100 |
| #1 | 1 | 1 | 1 | 4 | 5 | 8 | 12 | 19 | 25 | 33 | 51 | 74 |
| #1/0 | — | 1 | 1 | 3 | 4 | 7 | 10 | 16 | 21 | 27 | 43 | 63 |
| #2/0 | — | 1 | 1 | 2 | 3 | 6 | 8 | 13 | 18 | 23 | 36 | 52 |
| #3/0 | — | 1 | 1 | 1 | 3 | 5 | 7 | 11 | 15 | 19 | 30 | 43 |
| #4/0 | — | — | 1 | 1 | 1 | 4 | 6 | 9 | 12 | 16 | 25 | 36 |
| 250 kcmil | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 13 | 20 | 29 |
| 300 kcmil | — | — | 1 | 1 | 1 | 3 | 4 | 6 | 8 | 11 | 17 | 25 |
| 350 kcmil | — | — | — | 1 | 1 | 2 | 3 | 5 | 7 | 10 | 15 | 22 |
| 400 kcmil | — | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 8 | 13 | 20 |
| 500 kcmil | — | — | — | 1 | 1 | 1 | 2 | 4 | 5 | 7 | 11 | 16 |
— means a single conductor of that size does not fit.
RMC fill: XHHW-2
| Wire size | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" | 5" | 6" |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| #14 | 9 | 15 | 25 | 44 | 59 | 98 | 140 | 215 | 288 | 370 | 581 | 839 |
| #12 | 7 | 12 | 19 | 33 | 45 | 75 | 107 | 165 | 221 | 284 | 446 | 644 |
| #10 | 5 | 9 | 14 | 25 | 34 | 56 | 80 | 123 | 164 | 212 | 332 | 480 |
| #8 | 3 | 5 | 8 | 14 | 19 | 31 | 44 | 68 | 91 | 118 | 185 | 267 |
| #6 | 1 | 3 | 6 | 10 | 14 | 23 | 33 | 51 | 68 | 87 | 137 | 197 |
| #4 | 1 | 2 | 4 | 7 | 10 | 16 | 24 | 37 | 49 | 63 | 99 | 143 |
| #3 | 1 | 1 | 3 | 6 | 8 | 14 | 20 | 31 | 41 | 53 | 84 | 121 |
| #2 | 1 | 1 | 3 | 5 | 7 | 12 | 17 | 26 | 35 | 45 | 70 | 101 |
| #1 | 1 | 1 | 1 | 4 | 5 | 9 | 12 | 19 | 26 | 33 | 52 | 76 |
| #1/0 | — | 1 | 1 | 3 | 4 | 7 | 10 | 16 | 22 | 28 | 44 | 64 |
| #2/0 | — | 1 | 1 | 2 | 3 | 6 | 9 | 13 | 18 | 23 | 37 | 53 |
| #3/0 | — | 1 | 1 | 1 | 3 | 5 | 7 | 11 | 15 | 19 | 30 | 44 |
| #4/0 | — | — | 1 | 1 | 2 | 4 | 6 | 9 | 12 | 16 | 25 | 36 |
| 250 kcmil | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 13 | 20 | 30 |
| 300 kcmil | — | — | 1 | 1 | 1 | 3 | 4 | 6 | 9 | 11 | 18 | 25 |
| 350 kcmil | — | — | — | 1 | 1 | 2 | 3 | 6 | 7 | 10 | 15 | 22 |
| 400 kcmil | — | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 9 | 14 | 20 |
| 500 kcmil | — | — | — | 1 | 1 | 1 | 2 | 4 | 5 | 7 | 11 | 16 |
— means a single conductor of that size does not fit.
RMC fill: THW
| Wire size | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" | 5" | 6" |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| #14 | 9 | 15 | 25 | 44 | 59 | 98 | 140 | 215 | 288 | 370 | 581 | 839 |
| #12 | 7 | 12 | 19 | 33 | 45 | 75 | 107 | 165 | 221 | 284 | 446 | 644 |
| #10 | 5 | 9 | 14 | 25 | 34 | 56 | 80 | 123 | 164 | 212 | 332 | 480 |
| #8 | 3 | 5 | 8 | 14 | 19 | 31 | 44 | 68 | 91 | 118 | 185 | 267 |
| #6 | 1 | 3 | 5 | 8 | 11 | 18 | 27 | 41 | 55 | 71 | 111 | 160 |
| #4 | 1 | 1 | 3 | 6 | 8 | 14 | 20 | 31 | 41 | 53 | 83 | 120 |
| #3 | 1 | 1 | 3 | 5 | 7 | 12 | 17 | 26 | 35 | 45 | 71 | 103 |
| #2 | 1 | 1 | 2 | 4 | 6 | 10 | 14 | 22 | 30 | 38 | 60 | 87 |
| #1 | — | 1 | 1 | 3 | 4 | 7 | 10 | 15 | 21 | 27 | 42 | 61 |
| #1/0 | — | 1 | 1 | 2 | 3 | 6 | 8 | 13 | 18 | 23 | 36 | 52 |
| #2/0 | — | 1 | 1 | 1 | 3 | 5 | 7 | 11 | 15 | 19 | 31 | 44 |
| #3/0 | — | — | 1 | 1 | 2 | 4 | 6 | 9 | 13 | 16 | 26 | 37 |
| #4/0 | — | — | 1 | 1 | 1 | 3 | 5 | 8 | 10 | 14 | 21 | 31 |
| 250 kcmil | — | — | 1 | 1 | 1 | 3 | 4 | 6 | 8 | 11 | 17 | 25 |
| 300 kcmil | — | — | — | 1 | 1 | 2 | 3 | 5 | 7 | 9 | 15 | 22 |
| 350 kcmil | — | — | — | 1 | 1 | 1 | 3 | 5 | 6 | 8 | 13 | 19 |
| 400 kcmil | — | — | — | 1 | 1 | 1 | 3 | 4 | 6 | 7 | 12 | 17 |
| 500 kcmil | — | — | — | 1 | 1 | 1 | 1 | 3 | 5 | 6 | 10 | 14 |
— means a single conductor of that size does not fit.
Pick a trade size
RMC conduit fill questions
- How many #12 THHN wires fit in 1/2" RMC conduit?
- Up to 9 #12 THHN/THWN-2 conductors fit in 1/2" RMC under NEC 2026 Chapter 9 (40% fill for three or more wires).
- How many #12 THHN wires fit in 3/4" RMC conduit?
- Up to 16 #12 THHN/THWN-2 conductors fit in 3/4" RMC under NEC 2026 Chapter 9 (40% fill for three or more wires).
- How many #12 THHN wires fit in 1" RMC conduit?
- Up to 26 #12 THHN/THWN-2 conductors fit in 1" RMC under NEC 2026 Chapter 9 (40% fill for three or more wires).
- What is the fill limit for RMC?
- The same NEC 2026 Chapter 9 Table 1 limits apply to every raceway: 53% of the inside area for one wire, 31% for two and 40% for three or more. RMC only changes the inside area, from Table 4.
- Does a short RMC nipple get more fill?
- Yes. Chapter 9 Note 4 allows 60% fill for a nipple 24 inches or shorter between boxes or enclosures. The chart above uses the normal limits.
Other conduit types
You can read the NEC 2026 for free at NFPA free access. Need a different combination? Use the conduit fill calculator.