How many 12 gauge wires fit in 1/2 inch EMT?

Nine 12 AWG THHN in 1/2 in EMT and 16 in 3/4 in, from IRC Table E3904.6(1). In 1/2 in PVC Schedule 40 it is 8, and in Schedule 80 it is 6.

How many 10 gauge wires fit in 3/4 inch conduit?

Ten 10 AWG THHN in 3/4 in EMT, 9 in PVC Schedule 40 and 7 in PVC Schedule 80.

Do I need to work out the fill percentage?

Not for wires all of one type and size: Tables E3904.6 give the count directly. The percentage rule behind them, and the conductor areas for mixed fills, are in the NEC, which the residential code does not reprint.

Is THHN the same as THWN for conduit fill?

Yes in these tables: IRC Tables E3904.6 give THHN, THWN and THWN-2 one shared row, so the counts are the same.

Where is the conduit fill table in the NEC?

Annex C of the NEC. The residential code reprints it for dwellings as Tables E3904.6(1) through (10), one per raceway type.

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Conduit Fill Chart

IRC Tables E3904.6(1) to (10), the residential reprint of NEC Annex C

NEC Annex C's conduit fill tables are reprinted in the residential code as Tables E3904.6(1) to (10), one per raceway. The charts below are the three raceways most houses use, EMT and PVC Schedule 40 and 80, for THHN. The lookup covers all ten raceways and three wire types, and finds the smallest conduit for the number of wires you are pulling.

Find the conduit

Raceway

Wire type

Wire size

Wires to pull

no.

All conductors the same type and size, as the tables assume.

Specification summary

Generated from on . Reopen that address to reproduce these figures exactly.

Entered

Result

Worked example

Four 12 AWG THHN in EMT.

Table E3904.6(1), EMT. 12 AWG THHN: 9 in 1/2 in, 16 in 3/4 in.
Smallest. 1/2 in EMT holds four with room to spare.

The same four wires in PVC Schedule 80 also fit 1/2 in, which holds 6; ten would not.

The formula

A table lookup, not arithmetic:

smallest trade size = first column of the raceway's table whose count is at least the number of wires

raceway: each of the ten types has its own table, because wall thickness changes the bore
count: the most conductors of one type and size the table allows

The percentage fill rule the counts come from is in the NEC, which the residential code does not reprint; the counts are what it prints.

Where the numbers come from

IRC 2021 Tables E3904.6(1) to (10), read from the Utah Residential Code through UpCodes and confirmed identical in Virginia's adoption. They are the residential code's reprint of NEC Annex C for the THHN, XHHW and THW groups carried here.

Five cells in the flexible and IMC tables do not fit their neighbors; the conduit fill calculator lists them.

EMT

IRC Table E3904.6(1), Electrical Metallic Tubing: maximum THHN, THWN, THWN-2 conductors
Wire	1/2	3/4	1	1 1/4	1 1/2	2
14 AWG	12	22	35	61	84	138
12 AWG	9	16	26	45	61	101
10 AWG	5	10	16	28	38	63
8 AWG	3	6	9	16	22	36
6 AWG	2	4	7	12	16	26
4 AWG	1	2	4	7	10	16
3 AWG	1	1	3	6	8	13
2 AWG	1	1	3	5	7	11
1 AWG	1	1	1	4	5	8
1/0 AWG	1	1	1	3	4	7
2/0 AWG	0	1	1	2	3	6
3/0 AWG	0	1	1	1	3	5
4/0 AWG	0	1	1	1	2	4

PVC Schedule 40

IRC Table E3904.6(10), Rigid PVC Conduit Schedule 40: maximum THHN, THWN, THWN-2 conductors
Wire	1/2	3/4	1	1 1/4	1 1/2	2
14 AWG	11	21	34	60	82	135
12 AWG	8	15	25	43	59	99
10 AWG	5	9	15	27	37	62
8 AWG	3	5	9	16	21	36
6 AWG	1	4	6	11	15	26
4 AWG	1	2	4	7	9	16
3 AWG	1	1	3	6	8	13
2 AWG	1	1	3	5	7	11
1 AWG	1	1	1	3	5	8
1/0 AWG	1	1	1	3	4	7
2/0 AWG	0	1	1	2	3	6
3/0 AWG	0	1	1	1	3	5
4/0 AWG	0	1	1	1	2	4

PVC Schedule 80

IRC Table E3904.6(9), Rigid PVC Conduit Schedule 80: maximum THHN, THWN, THWN-2 conductors
Wire	1/2	3/4	1	1 1/4	1 1/2	2
14 AWG	9	17	28	51	70	118
12 AWG	6	12	20	37	51	86
10 AWG	4	7	13	23	32	54
8 AWG	2	4	7	13	18	31
6 AWG	1	3	5	9	13	22
4 AWG	1	1	3	6	8	14
3 AWG	1	1	3	5	7	12
2 AWG	1	1	2	4	6	10
1 AWG	0	1	1	3	4	7
1/0 AWG	0	1	1	2	3	6
2/0 AWG	0	1	1	1	3	5
3/0 AWG	0	1	1	1	2	4
4/0 AWG	0	0	1	1	1	3

Schedule 80 has the same outside diameter as Schedule 40 and a thicker wall, so the same trade size holds less:

Conductors in 1/2 in trade size, from the three tables above
Wire	EMT	PVC 40	PVC 80
12 AWG THHN	9	8	6
10 AWG THHN	5	5	4
6 AWG THHN	2	1	1

Nine 12 AWG THHN fit 1/2 in EMT and six fit 1/2 in PVC Schedule 80, a third fewer. Where the run changes from EMT to Schedule 80 PVC, size the conduit for the Schedule 80 section.

Frequently asked questions

How many 12 gauge wires fit in 1/2 inch EMT?: Nine 12 AWG THHN in 1/2 in EMT and 16 in 3/4 in, from IRC Table E3904.6(1). In 1/2 in PVC Schedule 40 it is 8, and in Schedule 80 it is 6.
How many 10 gauge wires fit in 3/4 inch conduit?: Ten 10 AWG THHN in 3/4 in EMT, 9 in PVC Schedule 40 and 7 in PVC Schedule 80.
Do I need to work out the fill percentage?: Not for wires all of one type and size: Tables E3904.6 give the count directly. The percentage rule behind them, and the conductor areas for mixed fills, are in the NEC, which the residential code does not reprint.
Is THHN the same as THWN for conduit fill?: Yes in these tables: IRC Tables E3904.6 give THHN, THWN and THWN-2 one shared row, so the counts are the same.
Where is the conduit fill table in the NEC?: Annex C of the NEC. The residential code reprints it for dwellings as Tables E3904.6(1) through (10), one per raceway type.

Check these numbers yourself

Utah Residential Code 2021, Chapter 39 Power and Lighting DistributionIRC 2021 as adopted in Utah, read through UpCodes. Tables E3904.6(1) to (10). Read 2026-09-13; Virginia's adoption prints all ten identically.

How every figure here is verified: Sources & Method. Who builds this: Lucas Pradella, and the method is on About. Found something wrong? Tell us and it gets fixed or removed.

Figures on this page last checked against the source documents on 2026-09-30. Codes are amended locally; confirm against the edition your jurisdiction enforces.

Related calculators

Dwelling tables from the residential code. Mixed conductor sizes, compact conductors and cable in raceway follow the NEC's conductor area tables.