Conduit Fill Chart
How many THHN/THWN-2 conductors of one AWG size fit in one EMT trade size, at the NEC 40% fill limit that applies to 3 or more conductors -- the case nearly every real circuit falls into. For a mixed-gauge run, or exactly 1 or 2 conductors, use the conduit fill calculator instead.
| EMT trade size | 14 AWG | 12 AWG | 10 AWG | 8 AWG | 6 AWG | 4 AWG | 3 AWG | 2 AWG | 1 AWG | 1/0 AWG | 2/0 AWG | 3/0 AWG | 4/0 AWG |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2" | 12 | 9 | 5 | 3 | 2 | 1 | 1 | 1 | — | — | — | — | — |
| 3/4" | 21 | 16 | 10 | 5 | 4 | 2 | 2 | 1 | 1 | 1 | — | — | — |
| 1" | 35 | 25 | 16 | 9 | 6 | 4 | 3 | 2 | 2 | 1 | 1 | 1 | 1 |
| 1-1/4" | 61 | 44 | 28 | 16 | 11 | 7 | 6 | 5 | 3 | 3 | 2 | 2 | 1 |
| 1-1/2" | 83 | 61 | 38 | 22 | 16 | 9 | 8 | 7 | 5 | 4 | 3 | 3 | 2 |
| 2" | 138 | 100 | 63 | 36 | 26 | 16 | 13 | 11 | 8 | 7 | 6 | 5 | 4 |
| 2-1/2" | 241 | 176 | 111 | 64 | 46 | 28 | 24 | 20 | 15 | 12 | 10 | 8 | 7 |
| 3" | 364 | 266 | 167 | 96 | 69 | 42 | 36 | 30 | 22 | 19 | 15 | 13 | 10 |
| 3-1/2" | 476 | 347 | 218 | 126 | 91 | 56 | 47 | 39 | 29 | 24 | 20 | 17 | 14 |
| 4" | 608 | 443 | 279 | 161 | 116 | 71 | 60 | 50 | 37 | 31 | 26 | 22 | 18 |
Max conductors of that single gauge, all THHN/THWN-2, at 40% fill (3-or-more conductors). Dashes mean none fit at that combination. Source: NEC (NFPA 70) Chapter 9, Tables 1, 4 and 5, 2026 edition (current as of this page, published September 2025); these values are unchanged from the 2020 and 2023 editions.
Where this chart comes from, and where it can disagree with another real source
Every number above is 40% of the EMT's Table 4 internal area, divided by that gauge's Table 5 THHN/THWN-2 area, rounded down to a whole conductor. That's the general NEC Chapter 9 method, and it's the only method that works for a conduit with mixed gauges. NEC's Annex C, Table C1 separately pre-publishes its own maximum counts for single-gauge THHN/THWN-2 groups specifically, computed with slightly different intermediate rounding, and its number for a given combination can land one conductor higher than the arithmetic here. Neither number is wrong; they're two real, different NEC-sourced ways of answering the same question, and where a permit or inspection turns on the exact count, Annex C, Table C1 is the code-recognized reference for that specific gauge and conduit combination. See the FAQ above for a worked example (12 AWG in 1" EMT: 25 here, 26 in Annex C).
Not applied
Bends and offsets (a run with several 90° bends pulls harder than the fill percentage alone suggests, even at the same nominal fill), rigid/PVC/IMC internal areas (all different from EMT's), non-THHN insulation types, mixed-gauge runs (see the conduit fill calculator), and local amendments. Conduit fill itself is a mechanical limit on whether conductors can be pulled through without jamming or damaging insulation -- it is separate from ampacity derating for more than three current-carrying conductors (NEC 310.15(C)), which the wire gauge chart and wire size calculator address instead.
This chart is for general reference and planning only. It is not a substitute for a licensed electrician's judgment or for checking your actual, locally adopted electrical code, which can differ from the base NEC shown here and always governs. Real electrical work should be verified against that code and, in most places, requires a permit and a licensed electrician.
Frequently Asked Questions
Why does this chart use the 40% fill limit and not 53% or 31%?
NEC Chapter 9, Table 1 sets 53% for exactly 1 conductor, 31% for exactly 2, and 40% for 3 or more. Almost every real circuit has at least three conductors -- a hot, a neutral or return, and a ground -- so 40% is the number that applies to nearly every actual pull. If you're running exactly 1 or 2 conductors in a conduit by themselves, use the conduit fill calculator, which applies the correct percentage for your exact count.
This chart says 25 conductors of 12 AWG fit in 1" EMT, but I've seen a chart that says 26. Which is right?
Both are real numbers from real NEC sources, and they can genuinely differ by one conductor -- this isn't a typo on either side. This chart is calculated directly from NEC Chapter 9 Table 1 (fill %), Table 4 (EMT area) and Table 5 (THHN/THWN-2 conductor area): 1" EMT is 0.864 sq in, 40% of that is 0.3456 sq in, and 12 AWG THHN is 0.0133 sq in each, so 0.3456 / 0.0133 = 25.98, which rounds down to 25. NEC's own Annex C, Table C1 pre-publishes maximum conductor counts for single-gauge THHN/THWN-2 groups directly, computed with its own rounding, and its number for this exact combination is 26. Where the two disagree, Annex C is the code-recognized number for the specific single-gauge combinations it lists; the Chapter 9 arithmetic here is the general method -- it's also the only method that works for a mixed-gauge run, which Annex C doesn't cover -- and it never comes out more permissive than Annex C, only occasionally one conductor more conservative. If an inspection or a permit depends on the exact count, check Annex C, Table C1 directly for that specific gauge and conduit combination.
Does this apply to rigid conduit, IMC or PVC, not just EMT?
No -- the 53/31/40% fill percentages apply to any raceway type, but the internal area they're a percentage of is different for each: EMT, rigid metal conduit, IMC and PVC all have different wall thickness and therefore different internal area at the same trade size. This chart is EMT only, the most common type in residential and light commercial work. Rigid and PVC have slightly less internal area than EMT at most trade sizes, so they fit slightly fewer conductors.
Does insulation type other than THHN/THWN-2 change these numbers?
Yes. THHN/THWN-2 is the standard building wire for conduit runs and what this chart uses, but other insulation types (XHHW, USE-2, etc.) have different outer diameters and therefore different cross-sectional areas per NEC Chapter 9, Table 5. Swapping insulation type without rechecking fill is a real, common mistake.
Can I mix wire gauges and still use this chart?
Not directly -- this chart is for a conduit filled with conductors that are all the same gauge. A mixed-gauge run (larger hots with a smaller ground, for example) is common, and fill for that case is based on total area, not a single gauge's count. Use the conduit fill calculator for that, which adds up the real area of each gauge you enter.
These calculators use National Electrical Code tables and industry sizing charts and are for planning. They are not a substitute for a licensed electrician, an HVAC contractor's Manual J load calculation, or your local code, which governs. Electrical work can kill you and may require a permit; when in doubt, hire it out.