Conduit Fill Chart (EMT)
Quick answer: how many conductors fit
Most questions about this chart are a count, not a percentage. These rows use the 40% allowance that applies to three or more conductors, so they answer the common case directly. The full matrix is below.
| Raceway | THHN/THWN-2 conductor | Maximum conductors (40%) |
|---|---|---|
| 1/2 in EMT | 12 AWG | 9 |
| 3/4 in EMT | 12 AWG | 16 |
| 3/4 in EMT | 10 AWG | 10 |
| 1 in EMT | 8 AWG | 9 |
| 1-1/4 in EMT | 6 AWG | 12 |
Maximum conductors per EMT trade size
Each cell is the largest number of conductors that still fits within the allowance for that count (53% for one, 31% for two, 40% for three or more), computed from the conduit internal area and the conductor area. Find the column for your conductor size, then read down to the smallest trade size with a count at least as large as the number you are installing.
| EMT trade size | 14 | 12 | 10 | 8 | 6 | 4 | 2 | 1/0 | 2/0 | 4/0 | 250 | 500 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2 in | 12 | 9 | 5 | 3 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
| 3/4 in | 22 | 16 | 10 | 6 | 4 | 2 | 1 | 1 | 1 | 0 | 0 | 0 |
| 1 in | 35 | 26 | 16 | 9 | 7 | 4 | 3 | 1 | 1 | 1 | 1 | 0 |
| 1-1/4 in | 61 | 45 | 28 | 16 | 12 | 7 | 5 | 3 | 2 | 1 | 1 | 1 |
| 1-1/2 in | 84 | 61 | 38 | 22 | 16 | 10 | 7 | 4 | 3 | 1 | 1 | 1 |
| 2 in | 138 | 101 | 63 | 36 | 26 | 16 | 11 | 7 | 6 | 4 | 3 | 1 |
| 2-1/2 in | 241 | 176 | 111 | 64 | 46 | 28 | 20 | 12 | 10 | 7 | 6 | 3 |
| 3 in | 364 | 266 | 167 | 96 | 69 | 43 | 30 | 19 | 16 | 11 | 9 | 5 |
| 3-1/2 in | 476 | 347 | 219 | 126 | 91 | 56 | 40 | 25 | 20 | 14 | 11 | 6 |
| 4 in | 608 | 443 | 279 | 161 | 116 | 71 | 51 | 32 | 26 | 18 | 15 | 8 |
Column headings are conductor sizes — AWG up to 4/0, kcmil at 250 and above. Conductor areas: NEC Chapter 9, Table 5 (THHN/THWN-2). Conduit internal areas: NEC Chapter 9, Table 4. Fill limits: NEC Chapter 9, Table 1.
The three fill allowances
Chapter 9, Table 1 sets the allowance by conductor count. The same raceway holds far less when a second conductor goes in, because two conductors jam against each other and heat has less room to escape.
| Conductors in the raceway | Maximum fill | Clause |
|---|---|---|
| One conductor | 53 % | NEC Chapter 9, Table 1 |
| Two conductors | 31 % | NEC Chapter 9, Table 1 |
| Three or more conductors | 40 % | NEC Chapter 9, Table 1 |
The full explanation, including why a single conductor is allowed 53%, is in the conduit fill percentage guide.
Worked example
Six 10 AWG THHN conductors in 1-1/4 in EMT — the same chain the calculator runs, with the clause behind each step.
| Step | Value | Clause |
|---|---|---|
| Conduit internal area | 1.496 sq in | NEC Chapter 9, Table 4 |
| Conductor area (each) | 0.0211 sq in | NEC Chapter 9, Table 5 (THHN/THWN-2) |
| Fill limit | 40 % | NEC Chapter 9, Table 1 |
| Total conductor area | 0.0211 x 6 = 0.1266 sq in | — |
| Actual fill percentage | Total conductor area / conduit area x 100 = 8.5 % | — |
| Maximum identical conductors | 28 | NEC Chapter 9, Table 1 and Note 7 |
The example stays within the 40% limit at 8.5% fill, and the same raceway would take up to 28 conductors of that size. Run your own numbers in the conduit fill calculator.
How to use the chart
- Count every conductor, including the ground. The equipment grounding conductor takes up space and counts toward fill, even though it is not a current-carrying conductor.
- Match the insulation. The areas here are THHN/THWN-2. A different insulation changes the outside area and can change the count by a conductor or two.
- Fill is not ampacity. A raceway filled to 40% is a space check. Once more than three current-carrying conductors share it, the ampacity calculator applies the adjustment factor as a separate step.
- Different raceway, different column. The quick reference prints the same counts for EMT, PVC schedule 40, rigid metal and IMC side by side.
- Conductor size and count are independent checks. Pick the smallest wire size the load needs first, then check it fits.
Frequently asked
- How many 12 AWG THHN conductors fit in 1/2 in EMT?
- 9 conductors at the 40% allowance that applies to three or more conductors. The count includes any equipment grounding conductor installed in the same raceway, because it takes up space.
- What is the 40% conduit fill rule?
- It is one of three fill allowances in Chapter 9, Table 1: up to 53% of the raceway internal area for a single conductor, 31% for two conductors, and 40% for three or more. The percentage is set by the conductor count, not by the conductor size.
- Does this chart apply to PVC, rigid metal or IMC?
- No. Every number here is computed for electrical metallic tubing (EMT). Other raceway types have their own internal areas, so choose the type in the conduit fill calculator instead of reusing the EMT column.
- Does the equipment grounding conductor count toward conduit fill?
- Yes. It occupies space in the raceway, so it belongs in the count when fill is checked. It does not count as a current-carrying conductor when the adjustment factor for conductors in a raceway is applied.
- Why is my count one off from a chart I found elsewhere?
- A one-conductor difference from Annex C is usually Chapter 9 Note 7: when identical conductors are calculated, a decimal fraction of 0.8 or larger rounds up. This chart applies that note. A remaining difference can still come from insulation type, because these cells are THHN/THWN-2 only, or from whether the equipment grounding conductor was included. These cells do not add a separate ground.
- What about a short raceway between two enclosures?
- A raceway 24 in or less between enclosures has a separate allowance in the same table and is not what this chart shows. Size those runs individually rather than reading a number off this page.
Cite this page
Use this reference in a report, article, course note or dataset. Calculated examples use this site's engine; reference data and explanatory text have separate sources and review status.
ElecCalcs. “Conduit Fill Chart (EMT).” Updated October 29, 2026. https://eleccalcs.com/conduit-fill-chart
Values reflect NEC 2023 and are pending review. Cite the edition you verified against.
Values are computed from NEC 2023 tables and are pending review. Verify before use. Educational information only — not professional engineering advice.