How many 12 AWG wires fit in a 3/4 inch conduit?

Sixteen 12 AWG THHN in 3/4 inch EMT, and fifteen in 3/4 inch PVC Schedule 40, when every conductor is the same size. Count the ground as one of them.

Does the ground wire count toward conduit fill?

Yes. Grounding and bonding conductors count for fill, using their actual dimensions. They do not count for ampacity derating, which is a different question with a different answer.

What if my wires are different sizes?

Then this chart does not apply. Add up each conductor's actual area and compare it with the raceway's limit; the round-up does not apply either. The conduit fill calculator does it for you.

Is 40% the limit for everything?

No. One conductor may fill 53%, two may fill 31%, and three or more 40%. The two-conductor case is the strictest and surprises people.

🧮 Conduit Fill Chart (NEC)

Canadian answer (CEC Table 8)

Last updated: September 16, 2026

The short answer

The two most-asked cases first: nine 12 AWG THHN fit a 1/2 inch EMT, and sixteen fit a 3/4 inch. The full chart is below, for EMT and for PVC Schedule 40, every wire size from 14 AWG to 500 kcmil.

EMT

Wire size (THHN/THWN-2)	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	2	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	1	3	4	7	12	19	25	32
2/0 AWG	0	1	1	2	3	6	10	16	20	26
3/0 AWG	0	1	1	1	3	5	8	13	17	22
4/0 AWG	0	1	1	1	2	4	7	11	14	18
250 kcmil	0	0	1	1	1	3	6	9	11	15
300 kcmil	0	0	1	1	1	3	5	7	10	13
350 kcmil	0	0	1	1	1	2	4	6	9	11
400 kcmil	0	0	0	1	1	1	4	6	8	10
500 kcmil	0	0	0	1	1	1	3	5	6	8

PVC Schedule 40

Wire size (THHN/THWN-2)	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
14 AWG	11	21	34	60	82	135	193	299	401	517
12 AWG	8	15	25	43	59	99	141	218	293	377
10 AWG	5	9	15	27	37	62	89	137	184	238
8 AWG	3	5	9	16	21	36	51	79	106	137
6 AWG	1	4	6	11	15	26	37	57	77	99
4 AWG	1	2	4	7	9	16	22	35	47	61
3 AWG	1	1	3	6	8	13	19	30	40	51
2 AWG	1	1	3	5	7	11	16	25	33	43
1 AWG	1	1	1	3	5	8	12	18	25	32
1/0 AWG	1	1	1	3	4	7	10	15	21	27
2/0 AWG	0	1	1	2	3	6	8	13	17	22
3/0 AWG	0	1	1	1	3	5	7	11	14	18
4/0 AWG	0	1	1	1	2	4	6	9	12	15
250 kcmil	0	0	1	1	1	3	4	7	10	12
300 kcmil	0	0	1	1	1	3	4	6	8	11
350 kcmil	0	0	1	1	1	2	3	5	7	9
400 kcmil	0	0	0	1	1	1	3	5	6	8
500 kcmil	0	0	0	1	1	1	2	4	5	7

Each count is the conduit's internal area times the fill limit the code sets for that number of conductors — 53% for one, 31% for two, 40% for three or more — divided by the conductor's own area from NEC Chapter 9 Table 5. Chapter 9 Note 7 then rounds the result up when the leftover reaches 0.8 of a conductor. Every cell here reproduces the published Annex C table, all 360 of them, and the verification suite fails if one drifts. How we verify.

Same size only

This chart is for conductors that are all the same size. That is what Annex C covers, and it is the one case the round-up applies to. Mix sizes in the same raceway and you add up actual areas instead — the calculator does that. Conduit Fill calculator

Three things that change the count

These are the ordinary solid and concentric-stranded numbers. Compact-stranded conductors are slimmer and have their own higher table, so treating them as the same wire understates what fits.

Count the equipment grounding conductor. It takes up room like any other conductor even though it carries no current, and its actual dimensions are used.

A nipple — a length of 24 inches or less between two enclosures — may be filled to 60%, so this chart is stricter than the code requires in that one case.

Canada does this differently

Canada answers this with different conduit, different wire and no round-up, so fewer conductors fit the same raceway: a metric 35 raceway — the Canadian 1-1/4 inch — takes nine 6 AWG RW90, where the NEC permits twelve 6 AWG THHN in 1-1/4 inch EMT. Never carry a number across the border.

Conduit Fill calculator · Derating table · Wire ampacity chart

Common questions

How many 12 AWG wires fit in a 3/4 inch conduit?: Sixteen 12 AWG THHN in 3/4 inch EMT, and fifteen in 3/4 inch PVC Schedule 40, when every conductor is the same size. Count the ground as one of them.
Does the ground wire count toward conduit fill?: Yes. Grounding and bonding conductors count for fill, using their actual dimensions. They do not count for ampacity derating, which is a different question with a different answer.
What if my wires are different sizes?: Then this chart does not apply. Add up each conductor's actual area and compare it with the raceway's limit; the round-up does not apply either. The conduit fill calculator does it for you.
Is 40% the limit for everything?: No. One conductor may fill 53%, two may fill 31%, and three or more 40%. The two-conductor case is the strictest and surprises people.