Conduit Fill Chart
How many wires fit in a conduit? Pick your conduit type for the full chart, or start with the quick tables below. Every number is worked out from NEC 2026 Chapter 9.
Updated
For reference only. Always verify with the NEC edition adopted by your AHJ.
Pick your conduit
Most #12 THHN wires, by conduit
The maximum number of #12 THHN/THWN-2 conductors at the 40% fill limit. A blank cell means that conduit has no such trade size in Table 4.
| Trade size | EMT | PVC Schedule 40 | PVC Schedule 80 | RMC | FMC |
|---|---|---|---|---|---|
| 1/2" | 9 | 8 | 6 | 9 | 9 |
| 3/4" | 16 | 15 | 12 | 16 | 16 |
| 1" | 26 | 25 | 20 | 26 | 24 |
| 1-1/4" | 45 | 43 | 37 | 46 | 38 |
| 1-1/2" | 61 | 59 | 51 | 62 | 56 |
| 2" | 101 | 99 | 86 | 102 | 98 |
| 2-1/2" | 176 | 141 | 124 | 146 | 147 |
| 3" | 266 | 218 | 193 | 225 | 212 |
| 3-1/2" | 347 | 293 | 261 | 301 | 289 |
| 4" | 443 | 377 | 338 | 387 | 378 |
| 5" | 608 | 594 | 537 | 608 | |
| 6" | 877 | 859 | 770 | 877 |
— means a single conductor of that size does not fit.
Most #10 THHN wires, by conduit
| Trade size | EMT | PVC Schedule 40 | PVC Schedule 80 | RMC | FMC |
|---|---|---|---|---|---|
| 1/2" | 5 | 5 | 4 | 6 | 6 |
| 3/4" | 10 | 9 | 7 | 10 | 10 |
| 1" | 16 | 15 | 13 | 17 | 15 |
| 1-1/4" | 28 | 27 | 23 | 29 | 24 |
| 1-1/2" | 38 | 37 | 32 | 39 | 35 |
| 2" | 63 | 62 | 54 | 64 | 62 |
| 2-1/2" | 111 | 89 | 78 | 92 | 93 |
| 3" | 167 | 137 | 122 | 142 | 134 |
| 3-1/2" | 219 | 184 | 164 | 189 | 182 |
| 4" | 279 | 238 | 213 | 244 | 238 |
| 5" | 383 | 374 | 338 | 383 | |
| 6" | 552 | 541 | 485 | 552 |
— means a single conductor of that size does not fit.
How the chart is worked out
Each count is the most conductors of one type and size that Chapter 9 allows in that conduit: 53% of the area for one wire, 31% for two, and 40% for three or more, with the Note 7 rounding where it applies. Wire areas come from Table 5 and conduit areas from Table 4. For a mix of wire sizes, use the conduit fill calculator.
Conduit fill questions
- How full can a conduit be under the NEC?
- Chapter 9, Table 1 sets the limit by wire count: 53% of the conduit area for one conductor, 31% for two, and 40% for three or more.
- Does a short nipple get a higher limit?
- Yes. Chapter 9, Note 4 allows 60% fill for a conduit or tubing nipple 24 inches or shorter. Tick the nipple box above to use it.
- What is the Note 7 rounding rule?
- When you work out the maximum number of conductors that fit and the decimal is 0.8 or higher, Chapter 9 Note 7 lets you round that number up to the next whole conductor. For example, 15.85 allowed wires becomes 16. It only applies when every conductor has the same insulation and size. The calculator applies it to three or more conductors.
- Which wire area does the calculator use?
- Chapter 9, Table 5 gives the area of each insulated conductor by type and size. THHN, THWN and THWN-2 share one set of values, as do XHHW and XHHW-2.
- Why does 3/8 flex conduit show an error?
- Table 4 lists 3/8 FMC, but NEC 348.20(A) only permits it for limited uses, and its fill is set by Table 348.22 rather than the Table 1 percentages. The calculator does not compute it. Check those sections for your installation.
- Can I rely on this for an inspection?
- It is a quick reference. Local amendments and the NEC edition your AHJ has adopted decide what passes, so confirm with them.
You can read the NEC 2026 for free at NFPA free access. Need a different combination? Use the conduit fill calculator.