How many 12 AWG wires fit in 1/2 inch PVC Sch 40?

Using nominal THHN outside diameters and the 40% fill rule, 8 12 AWG conductors fit in 1/2 inch PVC Sch 40. Every conductor counts, including the neutral and the equipment grounding conductor.

What is the maximum fill percentage for PVC conduit?

40% of the internal cross-sectional area for three or more conductors, 31% for exactly two and 53% for a single conductor. Nipples 24 inches or shorter are permitted at 60%.

What size PVC conduit do I need for three 10 AWG conductors?

Three 10 AWG THHN conductors need at least 1/2 inch PVC Sch 40 at 40% fill. Add a fourth conductor and re-check, because the count changes the usable area.

Does the ground wire count toward conduit fill?

Yes. Fill counts every conductor in the raceway. Grounds are excluded only from the ampacity adjustment count for current-carrying conductors, never from fill.

Where do these PVC conduit numbers come from?

Internal diameters are published product dimensions from the relevant ANSI/UL/ASTM product standards. Area is computed as pi times radius squared, and the conductor count is the largest whole number that fits inside the applicable fill percentage. No code table is reproduced.

PVC Conduit Fill Chart

Maximum conductor count for PVC Schedule 40 and Schedule 80 raceway, computed from published internal diameters and nominal THHN outside diameters.

Quick answer

1/2 inch PVC Schedule 40 holds 8 12 AWG THHN conductors and 3/4 inch holds 15. Schedule 80 has the same outside diameter but a thicker wall, so the same trade sizes hold 6 and 12. Fill limits are 40% for three or more conductors, 31% for two and 53% for one.

PVC conduit worked examples

1/2 in PVC Schedule 40 fill is 8 12 AWG THHN or 5 10 AWG. In 1 in Schedule 40, 6 #6 conductors fit; the same trade size in Schedule 80 takes 5.

Schedule 80 shares the outside diameter of Schedule 40 but the thicker wall costs roughly 15 to 25% of the usable area, so a run sized on a Schedule 40 chart can fail if the installed pipe is Schedule 80 — common where the raceway is exposed to physical damage. Check the print stamp on the pipe before you count.

PVC Schedule 40 — maximum THHN/THWN-2 conductors

Same-size conductors only. Mixed sizes need the conduit fill calculator.

Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
14 AWG	11	20	34	60	82	136	194	200	200	200
12 AWG	8	15	25	43	59	99	141	200	200	200
10 AWG	5	9	15	27	37	62	88	137	184	200
8 AWG	3	5	9	15	21	35	51	79	106	137
6 AWG	1	4	6	11	15	25	37	57	76	99
4 AWG	1	1	4	7	9	15	22	35	47	60
3 AWG	1	1	3	5	8	13	19	29	40	51
2 AWG	1	1	2	5	6	11	16	25	33	43
1 AWG	—	1	1	3	5	8	12	18	24	32
1/0 AWG	—	1	1	3	4	7	10	15	20	27
2/0 AWG	—	1	1	2	3	5	8	13	17	22
3/0 AWG	—	1	1	1	2	4	7	10	14	18
4/0 AWG	—	—	1	1	1	4	5	8	12	15

Counts computed at 53% for one conductor, 31% for two and 40% for three or more.

Published standard

PVC Schedule 80 — maximum THHN/THWN-2 conductors

Same-size conductors only. Mixed sizes need the conduit fill calculator.

Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
14 AWG	8	16	28	51	70	118	170	200	200	200
12 AWG	6	12	20	37	51	86	124	194	200	200
10 AWG	4	7	13	23	32	54	77	121	164	200
8 AWG	1	4	7	13	18	31	44	70	94	122
6 AWG	1	3	5	9	13	22	32	50	68	88
4 AWG	1	1	3	6	8	13	19	31	42	54
3 AWG	1	1	2	5	7	11	16	26	35	46
2 AWG	—	1	1	4	5	9	14	22	30	38
1 AWG	—	1	1	3	4	7	10	16	22	28
1/0 AWG	—	1	1	2	3	6	8	13	18	24
2/0 AWG	—	—	1	1	3	5	7	11	15	20
3/0 AWG	—	—	1	1	2	4	6	9	13	16
4/0 AWG	—	—	1	1	1	3	5	7	10	13

Counts computed at 53% for one conductor, 31% for two and 40% for three or more.

Published standard

PVC conduit internal area by trade size

Trade size	PVC Sch 40 area	PVC Sch 80 area
1/2"	0.285 (0.114)	0.217 (0.087)
3/4"	0.508 (0.203)	0.409 (0.164)
1"	0.832 (0.333)	0.688 (0.275)
1-1/4"	1.453 (0.581)	1.237 (0.495)
1-1/2"	1.986 (0.794)	1.711 (0.684)
2"	3.291 (1.316)	2.874 (1.150)
2-1/2"	4.695 (1.878)	4.119 (1.647)
3"	7.268 (2.907)	6.442 (2.577)
3-1/2"	9.737 (3.895)	8.688 (3.475)
4"	12.554 (5.022)	11.258 (4.503)

Total internal cross-sectional area in square inches, with the 40% usable figure in brackets.

Source & method: Area is A = π × (id / 2)². Internal diameters are nominal published product dimensions; see the methodology page.

Conductor outside diameters used

Size	Insulated OD (in)	Area (sq in)
18 AWG	0.084	0.0055
16 AWG	0.096	0.0072
14 AWG	0.111	0.0097
12 AWG	0.130	0.0133
10 AWG	0.164	0.0211
8 AWG	0.216	0.0366
6 AWG	0.254	0.0507
4 AWG	0.324	0.0824
3 AWG	0.352	0.0973
2 AWG	0.384	0.1158
1 AWG	0.446	0.1562
1/0 AWG	0.486	0.1855
2/0 AWG	0.532	0.2223
3/0 AWG	0.581	0.2651
4/0 AWG	0.642	0.3237
250 kcmil	0.711	0.3970
300 kcmil	0.766	0.4608
350 kcmil	0.817	0.5242
400 kcmil	0.864	0.5863
500 kcmil	0.949	0.7073
600 kcmil	1.051	0.8676
750 kcmil	1.158	1.0532

Nominal THHN/THWN-2 insulated outside diameter and the area each conductor consumes.

Frequently asked

How many 12 AWG wires fit in 1/2 inch PVC Sch 40?: Using nominal THHN outside diameters and the 40% fill rule, 8 12 AWG conductors fit in 1/2 inch PVC Sch 40. Every conductor counts, including the neutral and the equipment grounding conductor.
What is the maximum fill percentage for PVC conduit?: 40% of the internal cross-sectional area for three or more conductors, 31% for exactly two and 53% for a single conductor. Nipples 24 inches or shorter are permitted at 60%.
What size PVC conduit do I need for three 10 AWG conductors?: Three 10 AWG THHN conductors need at least 1/2 inch PVC Sch 40 at 40% fill. Add a fourth conductor and re-check, because the count changes the usable area.
Does the ground wire count toward conduit fill?: Yes. Fill counts every conductor in the raceway. Grounds are excluded only from the ampacity adjustment count for current-carrying conductors, never from fill.
Where do these PVC conduit numbers come from?: Internal diameters are published product dimensions from the relevant ANSI/UL/ASTM product standards. Area is computed as pi times radius squared, and the conductor count is the largest whole number that fits inside the applicable fill percentage. No code table is reproduced.

Mixed conductor sizes

These tables cover one conductor size at a time. Use the conduit fill calculator for mixed sizes, or see the full conduit fill chart for every raceway type side by side.