Conduit Fill Chart
See how many wires of one size fit each trade size of EMT, PVC, IMC or rigid conduit, and pick the exact wire and conduit for the answer.
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Wire diameter is the larger of the Southwire datasheet figure and the standard published dimension for the insulation, so for THHN/THWN-2 and XHHW-2 (stranded and solid) a count never exceeds what the standard dimensions give; conduit inside diameters are from Wheatland and CANTEX data. Limits: NEC Chapter 9 Table 1 (53 %, 31 %, 40 %) and the same-size rounding of Note 7. No code table is copied. In about one cell in seven the count is lower than a code-book table (never higher). Runs in your browser. Verify with your local code and a licensed electrician before you install.
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How to use the Conduit Fill Chart
- Choose the “Conduit type”: EMT, IMC, rigid (RMC), PVC Schedule 40 or PVC Schedule 80. PVC walls are thicker, so the same trade size holds fewer wires.
- Choose the “Wire insulation”: THHN/THWN-2 for most building wire, XHHW-2 for thicker insulation.
- Choose the “Wire size”, from 14 AWG to 1000 kcmil. Every conductor counted in the conduit is this one size.
- Choose the “Conduit trade size”, for example 3/4 in, to read the exact count for that pair.
- Read “Most conductors that fit”, then “Fill with that many” and “Fill allowed”. The steps show the wire area, the conduit area and the division.
- Open the advanced setting for a nipple of 24 in or less between enclosures; the limit becomes 60 %.
- Scroll to the chart under the result. It lists the count for every wire size (rows) and every trade size (columns) for the conduit type and insulation you chose.
- For wires of mixed sizes, such as three 12 AWG hots and one 10 AWG ground, use the conduit fill calculator, which adds the areas.
The example buttons load 12 AWG THHN in EMT and PVC, 10 AWG in PVC 80, 4/0 in rigid and 6 AWG XHHW-2 in IMC. “Copy result”, “Copy link” and “Print / save as PDF” keep the chart for the job.
Conduit fill chart for EMT
How many THHN/THWN-2 conductors of one size fit in EMT, at the 40 % limit:
| Wire | 1/2 in | 3/4 in | 1 in | 1-1/4 in | 1-1/2 in | 2 in | 2-1/2 in | 3 in | 4 in |
|---|---|---|---|---|---|---|---|---|---|
| 14 AWG | 12 | 21 | 34 | 59 | 81 | 134 | 233 | 353 | 588 |
| 12 AWG | 9 | 15 | 25 | 43 | 59 | 98 | 171 | 258 | 431 |
| 10 AWG | 5 | 10 | 16 | 28 | 38 | 62 | 109 | 165 | 276 |
| 8 AWG | 3 | 5 | 9 | 16 | 22 | 36 | 63 | 95 | 159 |
| 6 AWG | 1 | 4 | 7 | 12 | 16 | 26 | 46 | 69 | 116 |
| 4 AWG | 1 | 2 | 4 | 7 | 10 | 16 | 28 | 43 | 71 |
| 3 AWG | 1 | 1 | 3 | 6 | 8 | 13 | 24 | 36 | 60 |
| 2 AWG | 1 | 1 | 3 | 5 | 7 | 11 | 20 | 30 | 51 |
| 1 AWG | 1 | 1 | 1 | 4 | 5 | 8 | 15 | 22 | 37 |
| 1/0 AWG | 0 | 1 | 1 | 3 | 4 | 7 | 12 | 19 | 32 |
| 2/0 AWG | 0 | 1 | 1 | 2 | 3 | 6 | 10 | 16 | 26 |
| 3/0 AWG | 0 | 1 | 1 | 1 | 3 | 5 | 8 | 13 | 22 |
| 4/0 AWG | 0 | 0 | 1 | 1 | 1 | 4 | 7 | 11 | 18 |
Conduit fill chart for PVC Schedule 40
PVC Schedule 40 has thicker walls than EMT, so the inside area is smaller at every trade size and the counts are lower:
| Wire | 1/2 in | 3/4 in | 1 in | 1-1/4 in | 1-1/2 in | 2 in | 2-1/2 in | 3 in | 4 in |
|---|---|---|---|---|---|---|---|---|---|
| 14 AWG | 11 | 20 | 33 | 57 | 79 | 131 | 186 | 289 | 499 |
| 12 AWG | 8 | 14 | 24 | 42 | 58 | 96 | 137 | 212 | 366 |
| 10 AWG | 5 | 9 | 15 | 27 | 37 | 61 | 87 | 135 | 234 |
| 8 AWG | 3 | 5 | 9 | 15 | 21 | 35 | 50 | 78 | 135 |
| 6 AWG | 1 | 4 | 6 | 11 | 15 | 26 | 37 | 57 | 99 |
| 4 AWG | 1 | 1 | 4 | 7 | 9 | 16 | 22 | 35 | 60 |
| 3 AWG | 1 | 1 | 3 | 6 | 8 | 13 | 19 | 29 | 51 |
| 2 AWG | 1 | 1 | 3 | 5 | 7 | 11 | 16 | 25 | 43 |
| 1 AWG | 0 | 1 | 1 | 3 | 5 | 8 | 12 | 18 | 32 |
| 1/0 AWG | 0 | 1 | 1 | 3 | 4 | 7 | 10 | 15 | 27 |
| 2/0 AWG | 0 | 1 | 1 | 2 | 3 | 6 | 8 | 13 | 22 |
| 3/0 AWG | 0 | 0 | 1 | 1 | 3 | 5 | 7 | 11 | 18 |
| 4/0 AWG | 0 | 0 | 1 | 1 | 1 | 4 | 5 | 9 | 15 |
How is the conduit fill chart calculated?
Each count is the number of wires whose areas add up to no more than the allowed share of the conduit’s inside area. The wire area is π/4 × d², the conduit area is π/4 × ID². For 12 AWG THHN in 3/4 in EMT: the wire’s outside diameter is 0.132 in (area 0.01368 in²), the conduit’s inside diameter is 0.824 in (area 0.5333 in²), 40 % of that is 0.2133 in², and 0.2133 ÷ 0.01368 = 15.6, so 15 wires.
The limits come from NEC Chapter 9, Table 1: 53 % for one conductor, 31 % for two and 40 % for more than two, 60 % in a nipple of 24 in or less. Table 1 Note 7 allows a count with a decimal of 0.8 or more to be rounded up when all conductors are the same size; the chart uses that rule, so 8.88 wires of 12 AWG in 1/2 in EMT shows as 9.
Why does PVC hold fewer wires than EMT?
Inside diameter is what counts. 3/4 in EMT is 0.824 in inside, while 3/4 in PVC Schedule 40 is about 0.802 in and Schedule 80 about 0.720 in. For 12 AWG THHN in 3/4 in that gives 15 in EMT, 14 in PVC 40 and 12 in PVC 80.
Worked examples
| Input | Result |
|---|---|
| 12 AWG THHN/THWN-2 (stranded), 3/4 in EMT | 15 conductors fit (38.5 % fill) |
| 10 AWG THHN/THWN-2 (stranded), 1/2 in EMT | 5 conductors fit (35.2 % fill) |
| 6 AWG THHN/THWN-2 (stranded), 1 in PVC Schedule 40 | 6 conductors fit (36.8 % fill) |
| 4/0 AWG XHHW-2 (stranded), 3 in Rigid (RMC) | 9 conductors fit (38.4 % fill) |
| 12 AWG THHN/THWN-2 (stranded), 1/2 in EMT, nipple | 13 conductors fit (58.5 % fill) |
Calculated by the tool above; open it with the same values to see each step.
Questions, briefly answered
How many wires fit in 1/2 inch EMT?
Nine 12 AWG THHN wires, twelve 14 AWG or five 10 AWG, all at the 40 % limit. Count the ground wire as one of them.
How many 12 gauge wires fit in 3/4 inch conduit?
Fifteen 12 AWG THHN in EMT, 14 in PVC Schedule 40 and 12 in PVC Schedule 80. Rigid gives 16 and IMC 17 because their inside diameters are larger.
What percent fill is allowed in conduit?
53 % for one conductor, 31 % for two and 40 % for three or more (NEC Chapter 9, Table 1). A nipple of 24 in or less between enclosures may be filled to 60 %.
Do ground wires count toward conduit fill?
Yes. Equipment grounding and bonding conductors are counted like any other conductor (Chapter 9, Table 1, Note 3), bare or insulated, using their actual diameter. This chart covers THHN/THWN-2 and XHHW-2 only; for a bare ground wire add its area in the conduit fill calculator.
Why does my printed conduit fill table show a different number?
This chart takes each wire’s diameter as the larger of the Southwire datasheet figure and the standard published dimension for that insulation (THHN/THWN-2 and XHHW-2), then divides the conduit’s allowed area by it. A printed table uses the standard area with the code’s own conduit areas. Compared cell by cell, this chart shows the same count in most cells and fewer wires, never more, in about one cell in seven: 179 of 1,155 THHN cells and 161 of 1,210 XHHW-2 cells checked. In 19 and 15 of those cells the gap is 5 % or more of the count, the largest being 14 AWG in a 6 in conduit; the small wires in large conduit are where it shows. The number your inspector uses is the one in the code edition adopted where you work. RHW-2/USE-2 and bare copper are not in this chart because no verified standard dimension was available for every size; use the conduit fill calculator for them (it uses maker figures there).
Can I use this chart for different wire sizes in one conduit?
No, the chart is for one size at a time. For mixed sizes add the areas with the conduit fill calculator, or find the smallest conduit for a set of wires.
What is more than three current-carrying conductors?
Once more than three conductors in a conduit carry current, the ampacity of each is reduced by the factors of NEC 310.15(C)(1). The chart tells you only how many fit, not how many may carry load.