NEC 2026
FMC Conduit Fill Chart
FMC (flexible metal conduit, NEC Article 348) is the "Greenfield" flex used for short runs and connections to equipment. 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.
FMC 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" |
|---|---|---|---|---|---|---|---|---|---|---|
| #14 | 13 | 22 | 33 | 52 | 76 | 135 | 202 | 291 | 396 | 518 |
| #12 | 9 | 16 | 24 | 38 | 56 | 98 | 147 | 212 | 289 | 378 |
| #10 | 6 | 10 | 15 | 24 | 35 | 62 | 93 | 134 | 182 | 238 |
| #8 | 3 | 6 | 9 | 14 | 20 | 35 | 53 | 77 | 105 | 137 |
| #6 | 1 | 4 | 6 | 10 | 14 | 25 | 38 | 55 | 76 | 99 |
| #4 | 1 | 2 | 4 | 6 | 9 | 16 | 24 | 34 | 46 | 61 |
| #3 | 1 | 1 | 3 | 5 | 7 | 13 | 20 | 29 | 39 | 51 |
| #2 | 1 | 1 | 3 | 4 | 6 | 11 | 17 | 24 | 33 | 43 |
| #1 | 1 | 1 | 1 | 3 | 4 | 8 | 12 | 18 | 24 | 32 |
| #1/0 | — | 1 | 1 | 2 | 4 | 7 | 10 | 15 | 20 | 27 |
| #2/0 | — | 1 | 1 | 1 | 3 | 6 | 9 | 12 | 17 | 22 |
| #3/0 | — | 1 | 1 | 1 | 2 | 5 | 7 | 10 | 14 | 18 |
| #4/0 | — | — | 1 | 1 | 1 | 4 | 6 | 8 | 12 | 15 |
| 250 kcmil | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 9 | 12 |
| 300 kcmil | — | — | — | 1 | 1 | 3 | 4 | 6 | 8 | 11 |
| 350 kcmil | — | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 9 |
| 400 kcmil | — | — | — | 1 | 1 | 1 | 3 | 5 | 6 | 8 |
| 500 kcmil | — | — | — | — | 1 | 1 | 2 | 4 | 5 | 7 |
— means a single conductor of that size does not fit.
FMC 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" |
|---|---|---|---|---|---|---|---|---|---|---|
| #14 | 9 | 15 | 23 | 36 | 53 | 94 | 141 | 203 | 277 | 361 |
| #12 | 7 | 11 | 18 | 28 | 41 | 72 | 108 | 156 | 212 | 277 |
| #10 | 5 | 8 | 13 | 21 | 30 | 54 | 81 | 116 | 158 | 207 |
| #8 | 3 | 5 | 7 | 11 | 17 | 30 | 45 | 64 | 88 | 115 |
| #6 | 1 | 3 | 5 | 8 | 12 | 22 | 33 | 48 | 65 | 85 |
| #4 | 1 | 2 | 4 | 6 | 9 | 16 | 24 | 34 | 47 | 61 |
| #3 | 1 | 1 | 3 | 5 | 7 | 13 | 20 | 29 | 40 | 52 |
| #2 | 1 | 1 | 3 | 4 | 6 | 11 | 17 | 24 | 33 | 44 |
| #1 | 1 | 1 | 1 | 3 | 5 | 8 | 13 | 18 | 25 | 32 |
| #1/0 | — | 1 | 1 | 2 | 4 | 7 | 10 | 15 | 21 | 27 |
| #2/0 | — | 1 | 1 | 1 | 3 | 6 | 9 | 13 | 17 | 23 |
| #3/0 | — | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 14 | 19 |
| #4/0 | — | — | 1 | 1 | 1 | 4 | 6 | 9 | 12 | 15 |
| 250 kcmil | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 13 |
| 300 kcmil | — | — | — | 1 | 1 | 3 | 4 | 6 | 8 | 11 |
| 350 kcmil | — | — | — | 1 | 1 | 1 | 4 | 5 | 7 | 9 |
| 400 kcmil | — | — | — | 1 | 1 | 1 | 3 | 5 | 6 | 8 |
| 500 kcmil | — | — | — | — | 1 | 1 | 3 | 4 | 5 | 7 |
— means a single conductor of that size does not fit.
FMC fill: THW
| Wire size | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" |
|---|---|---|---|---|---|---|---|---|---|---|
| #14 | 9 | 15 | 23 | 36 | 53 | 94 | 141 | 203 | 277 | 361 |
| #12 | 7 | 11 | 18 | 28 | 41 | 72 | 108 | 156 | 212 | 277 |
| #10 | 5 | 8 | 13 | 21 | 30 | 54 | 81 | 116 | 158 | 207 |
| #8 | 3 | 5 | 7 | 11 | 17 | 30 | 45 | 64 | 88 | 115 |
| #6 | 1 | 3 | 4 | 7 | 10 | 18 | 27 | 39 | 53 | 69 |
| #4 | 1 | 1 | 3 | 5 | 7 | 13 | 20 | 29 | 39 | 51 |
| #3 | 1 | 1 | 3 | 4 | 6 | 11 | 17 | 25 | 34 | 44 |
| #2 | 1 | 1 | 1 | 4 | 5 | 10 | 14 | 21 | 29 | 37 |
| #1 | — | 1 | 1 | 2 | 4 | 7 | 10 | 15 | 20 | 26 |
| #1/0 | — | 1 | 1 | 1 | 3 | 6 | 9 | 12 | 17 | 22 |
| #2/0 | — | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 14 | 19 |
| #3/0 | — | — | 1 | 1 | 1 | 4 | 6 | 9 | 12 | 16 |
| #4/0 | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 13 |
| 250 kcmil | — | — | — | 1 | 1 | 3 | 4 | 6 | 8 | 11 |
| 300 kcmil | — | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 9 |
| 350 kcmil | — | — | — | 1 | 1 | 1 | 3 | 4 | 6 | 8 |
| 400 kcmil | — | — | — | 1 | 1 | 1 | 3 | 4 | 6 | 7 |
| 500 kcmil | — | — | — | — | 1 | 1 | 1 | 3 | 5 | 6 |
— means a single conductor of that size does not fit.
3/8" FMC is left out. NEC 348.20(A) restricts where it can be used and Table 348.22 sets its fill, rather than the Chapter 9 percentages.
Pick a trade size
FMC conduit fill questions
- How many #12 THHN wires fit in 1/2" FMC conduit?
- Up to 9 #12 THHN/THWN-2 conductors fit in 1/2" FMC under NEC 2026 Chapter 9 (40% fill for three or more wires).
- How many #12 THHN wires fit in 3/4" FMC conduit?
- Up to 16 #12 THHN/THWN-2 conductors fit in 3/4" FMC under NEC 2026 Chapter 9 (40% fill for three or more wires).
- How many #12 THHN wires fit in 1" FMC conduit?
- Up to 24 #12 THHN/THWN-2 conductors fit in 1" FMC under NEC 2026 Chapter 9 (40% fill for three or more wires).
- What is the fill limit for FMC?
- 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. FMC only changes the inside area, from Table 4.
- Does a short FMC 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.