EMT Conduit Fill Chart (THHN/THWN-2)
The most conductors of one size allowed in each EMT trade size, worked out from NEC Chapter 9 Tables 4 and 5 the same way Annex C Table C.1 is. Find your wire size on the left and read across.
| Wire size | 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 | 241 | 364 | 476 | 608 |
| 12 AWG | 9 | 16 | 26 | 45 | 61 | 101 | 176 | 266 | 347 | 443 |
| 10 AWG | 5 | 10 | 16 | 28 | 38 | 63 | 111 | 167 | 219 | 279 |
| 8 AWG | 3 | 6 | 9 | 16 | 22 | 36 | 64 | 96 | 126 | 161 |
| 6 AWG | 1 | 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 | 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 | 4 | 7 | 11 | 14 | 18 |
| 250 kcmil | — | — | 1 | 1 | 1 | 3 | 6 | 9 | 11 | 15 |
| 300 kcmil | — | — | — | 1 | 1 | 3 | 5 | 7 | 10 | 13 |
Rows are THHN/THWN-2 copper. A dash means even a single conductor of that size exceeds the 53% limit for that trade size. When a count works out to a fraction of 0.8 or more, it is rounded up (Chapter 9, Note 7).
EMT internal area and 40% fill
Chapter 9 Table 1 lets three or more conductors fill 40% of the conduit’s internal area. These are the areas the chart divides by.
| Trade size | Total area | 40% fill area |
|---|---|---|
| 1/2" | 0.304 in² | 0.122 in² |
| 3/4" | 0.533 in² | 0.213 in² |
| 1" | 0.864 in² | 0.346 in² |
| 1-1/4" | 1.496 in² | 0.598 in² |
| 1-1/2" | 2.036 in² | 0.814 in² |
| 2" | 3.356 in² | 1.342 in² |
| 2-1/2" | 5.858 in² | 2.343 in² |
| 3" | 8.846 in² | 3.538 in² |
| 3-1/2" | 11.545 in² | 4.618 in² |
| 4" | 14.753 in² | 5.901 in² |
How to read and use the chart
- The counts are for one wire size and one insulation type at a time. For a mix of sizes, add up each conductor’s area instead.
- One conductor may fill 53% of the conduit and two conductors 31%; three or more, 40%.
- Equipment grounding conductors count toward fill like any other conductor.
- Fill is only one limit: more than three current-carrying conductors in a raceway also reduce each one’s ampacity (Table 310.15(C)(1)).
For mixed wire sizes, use the conduit fill calculator.
In-depth guide: Conduit fill rules: how NEC Chapter 9 sizes a raceway
Worked example
Three 12 AWG THHN conductors (a 20 A circuit with its ground) in 1/2" EMT.
Each 12 AWG THHN is 0.0133 in², so three take 0.0399 in². The 40% area of 1/2" EMT is 0.122 in², so they fit with room to spare; the chart shows 9 is the limit.
Going to 3/4" EMT raises the limit to 16 conductors of 12 AWG, enough for several circuits — remember to derate ampacity once more than three are current-carrying.
Frequently asked questions
How many 12 AWG wires can go in 3/4" EMT?
Sixteen THHN/THWN-2 conductors, from NEC Chapter 9 and Annex C Table C.1. For 14 AWG it is 22, and for 10 AWG it is 10.
How many wires in 1/2" EMT?
Twelve 14 AWG, nine 12 AWG, five 10 AWG or three 8 AWG THHN conductors.
Does the ground wire count in conduit fill?
Yes. Equipment grounding conductors count toward fill like any other conductor, using their own area.
Why does the 3-or-more limit drop to 40%?
More conductors mean more heat and harder pulls. Chapter 9 Table 1 sets 53% for one conductor, 31% for two and 40% for three or more.
Sources
Sources, checks and limits for this calculator →
Related calculators
Embed this calculator
Free to use on your own website, blog, or training material — paste this code where you want the calculator to appear.