NEC Conduit Fill Chart
Everything conduit fill runs on, in one place: the fill percentages of Chapter 9 Table 1, a computed chart of maximum THHN/THWN-2 conductors in EMT, the raceway internal areas of Table 4 for seven raceway types, and the conductor areas of Table 5.
Need a sized answer, not a lookup? Open the free Conduit Fill Calculator. It reads this same dataset and shows every step.
| Conductors in the raceway | Maximum fill |
|---|---|
| One conductor | 53% |
| Two conductors | 31% |
| Three or more conductors | 40% |
| Nipple, 24 in or shorter, any count | 60% |
Fill limits per NEC Ch. 9 Table 1. Nipples not exceeding 24 inches may be filled to 60% · Ch. 9 Note 4.
| Conductor | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" |
|---|---|---|---|---|---|---|---|---|---|---|
| 14 AWG | 12 | 22 | 35 | 61 | 84 | 138 | 200 | 200 | 200 | 200 |
| 12 AWG | 9 | 16 | 26 | 45 | 61 | 101 | 176 | 200 | 200 | 200 |
| 10 AWG | 5 | 10 | 16 | 28 | 38 | 63 | 111 | 167 | 200 | 200 |
| 8 AWG | 3 | 6 | 9 | 16 | 22 | 36 | 64 | 96 | 126 | 161 |
| 6 AWG | 2 | 4 | 7 | 12 | 16 | 26 | 46 | 69 | 91 | 116 |
| 4 AWG | 1 | 2 | 4 | 7 | 10 | 16 | 28 | 43 | 56 | 71 |
| 3 AWG | 1 | 1 | 3 | 6 | 8 | 13 | 24 | 36 | 47 | 60 |
| 2 AWG | 1 | 1 | 3 | 5 | 7 | 11 | 20 | 30 | 40 | 51 |
| 1 AWG | 1 | 1 | 1 | 4 | 5 | 8 | 15 | 22 | 29 | 37 |
| 1/0 AWG | 1 | 1 | 1 | 3 | 4 | 7 | 12 | 19 | 25 | 32 |
| 2/0 AWG | – | 1 | 1 | 2 | 3 | 6 | 10 | 16 | 20 | 26 |
| 3/0 AWG | – | 1 | 1 | 1 | 3 | 5 | 8 | 13 | 17 | 22 |
| 4/0 AWG | – | 1 | 1 | 1 | 2 | 4 | 7 | 11 | 14 | 18 |
| 250 kcmil | – | – | 1 | 1 | 1 | 3 | 6 | 9 | 11 | 15 |
| 300 kcmil | – | – | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 13 |
| 350 kcmil | – | – | 1 | 1 | 1 | 2 | 4 | 6 | 9 | 11 |
| 400 kcmil | – | – | – | 1 | 1 | 1 | 4 | 6 | 8 | 10 |
| 500 kcmil | – | – | – | 1 | 1 | 1 | 3 | 5 | 6 | 8 |
| 600 kcmil | – | – | – | 1 | 1 | 1 | 2 | 4 | 5 | 7 |
| 700 kcmil | – | – | – | 1 | 1 | 1 | 2 | 3 | 4 | 6 |
| 750 kcmil | – | – | – | – | 1 | 1 | 1 | 3 | 4 | 5 |
| 1000 kcmil | – | – | – | – | 1 | 1 | 1 | 2 | 3 | 4 |
Counts computed from the EMT areas of Ch. 9 Table 4 and the conductor areas of Ch. 9 Table 5, with the fill limits of Ch. 9 Table 1 and the rounding allowance of Ch. 9 Note 7, exactly as the JobVolt conduit fill calculator checks a run. For mixed conductor sizes or types, fill must be computed by area, not read from this chart.
| Trade size | EMT | ENT | FMC | IMC | RMC (rigid) | PVC Sch 40 | PVC Sch 80 |
|---|---|---|---|---|---|---|---|
| 1/2" | 0.304 | 0.285 | 0.317 | 0.342 | 0.314 | 0.285 | 0.217 |
| 3/4" | 0.533 | 0.508 | 0.533 | 0.586 | 0.549 | 0.508 | 0.409 |
| 1" | 0.864 | 0.832 | 0.817 | 0.959 | 0.887 | 0.832 | 0.688 |
| 1-1/4" | 1.496 | 1.453 | 1.277 | 1.647 | 1.526 | 1.453 | 1.237 |
| 1-1/2" | 2.036 | 1.986 | 1.858 | 2.225 | 2.071 | 1.986 | 1.711 |
| 2" | 3.356 | 3.291 | 3.269 | 3.630 | 3.408 | 3.291 | 2.874 |
| 2-1/2" | 5.858 | – | 4.909 | 5.135 | 4.866 | 4.695 | 4.119 |
| 3" | 8.846 | – | 7.069 | 7.922 | 7.499 | 7.268 | 6.442 |
| 3-1/2" | 11.545 | – | 9.621 | 10.584 | 10.010 | 9.737 | 8.688 |
| 4" | 14.753 | – | 12.566 | 13.631 | 12.882 | 12.554 | 11.258 |
| 5" | – | – | – | – | 20.212 | 19.761 | 17.855 |
| 6" | – | – | – | – | 29.158 | 28.567 | 25.598 |
Total internal areas per NEC Ch. 9 Table 4. Multiply by the Table 1 percentage that matches your conductor count to get the allowable fill area. A dash means the raceway is not made in that trade size.
| Conductor | THHN / THWN-2 | XHHW-2 / XHH | THW / THHW / THW-2 | TW |
|---|---|---|---|---|
| 14 AWG | 0.0097 | 0.0139 | 0.0139 | 0.0139 |
| 12 AWG | 0.0133 | 0.0181 | 0.0181 | 0.0181 |
| 10 AWG | 0.0211 | 0.0243 | 0.0243 | 0.0243 |
| 8 AWG | 0.0366 | 0.0437 | 0.0437 | 0.0437 |
| 6 AWG | 0.0507 | 0.0590 | 0.0726 | 0.0726 |
| 4 AWG | 0.0824 | 0.0814 | 0.0973 | 0.0973 |
| 3 AWG | 0.0973 | 0.0962 | 0.1134 | 0.1134 |
| 2 AWG | 0.1158 | 0.1146 | 0.1333 | 0.1333 |
| 1 AWG | 0.1562 | 0.1534 | 0.1901 | 0.1901 |
| 1/0 AWG | 0.1855 | 0.1825 | 0.2223 | – |
| 2/0 AWG | 0.2223 | 0.2190 | 0.2624 | – |
| 3/0 AWG | 0.2679 | 0.2642 | 0.3117 | – |
| 4/0 AWG | 0.3237 | 0.3197 | 0.3718 | – |
| 250 kcmil | 0.3970 | 0.3904 | 0.4596 | – |
| 300 kcmil | 0.4608 | 0.4536 | 0.5281 | – |
| 350 kcmil | 0.5242 | 0.5166 | 0.5958 | – |
| 400 kcmil | 0.5863 | 0.5782 | 0.6619 | – |
| 500 kcmil | 0.7073 | 0.6984 | 0.7901 | – |
| 600 kcmil | 0.8676 | 0.8709 | 0.9729 | – |
| 700 kcmil | 0.9887 | 0.9923 | 1.1010 | – |
| 750 kcmil | 1.0496 | 1.0532 | 1.1652 | – |
| 1000 kcmil | 1.3478 | 1.3519 | 1.4784 | – |
Approximate areas of insulated conductors per NEC Ch. 9 Table 5. Sum the areas of every conductor in the raceway and compare against the allowable fill area from Tables 1 and 4.
How conduit fill works
Fill is an area problem. Each insulated conductor occupies the area listed in Chapter 9 Table 5. The raceway offers the internal area listed in Chapter 9 Table 4. Table 1 says how much of that area you may use: 53% for one conductor, 31% for two, 40% for three or more, and 60% for a nipple 24 inches or shorter. If the summed conductor area fits inside the allowed area, the run complies.
Reading the EMT chart
The chart answers the everyday question directly: how many conductors of one size fit in a given EMT trade size. It applies the Note 7 allowance, which lets the count round up when the division lands at 0.8 or higher past the whole number. The moment you mix sizes or insulation types in one raceway, the chart no longer applies and the calculation goes back to areas. The free conduit fill calculator handles mixed pulls, all seven raceway types and nipples, and shows the areas it used.
Two traps worth knowing
First, three conductors around a bend can wedge when the conduit inner diameter divided by the conductor diameter lands near 3.0. The calculator flags that jam-ratio window. Second, PVC Schedule 80 has a thicker wall than Schedule 40, so the same trade size holds noticeably less. Check the Table 4 columns above before assuming a size that worked in EMT will work in Schedule 80.
This table lives in the app, offline.
JobVolt opens the right NEC table from any result with your row highlighted, works with no signal, and turns calculations into inspector-ready PDF submittals on your letterhead.
