PVC Schedule 40 Conduit Fill Chart

Rigid PVC Conduit, Schedule 40 — NEC Article 352. Gray nonmetallic conduit for underground runs, slabs and wet or corrosive locations. Needs a separate equipment grounding conductor, which counts toward fill.

1/2-inch PVC Schedule 40 holds 8 #12 THHN conductors; 3/4-inch holds 15. Counts assume 40% fill with all conductors the same size.

PVC Schedule 40 fill calculator

Conduit type

Trade size

Run length Nipple, 24 in. or shorter (60%)

Loading calculator…

PVC Schedule 40 sizes

One page per trade size, with counts for every insulation type side by side.

PVC Schedule 40 fill chart — THHN / THWN-2

Thermoplastic insulation with a nylon jacket. The thinnest common building wire, so it gives the highest conductor counts. Nearly all pulled wire sold in North America is dual-rated THHN/THWN-2.

Maximum THHN conductors in PVC Schedule 40 — 40% fill (53% for one wire, 31% for two)
Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"	5"	6"
14 AWG	11	21	34	60	82	135	193	299	401	517	815	1178
12 AWG	8	15	25	43	59	99	141	218	293	377	594	859
10 AWG	5	9	15	27	37	62	89	137	184	238	374	541
8 AWG	3	5	9	16	21	36	51	79	106	137	216	312
6 AWG	1	4	6	11	15	26	37	57	77	99	156	225
4 AWG	1	1	4	7	9	16	22	35	47	61	96	138
3 AWG	1	1	3	6	8	13	19	30	40	51	81	117
2 AWG	1	1	3	5	7	11	16	25	33	43	68	98
1 AWG	—	1	1	3	5	8	12	18	25	32	50	73
1/0 AWG	—	1	1	3	4	7	10	15	21	27	42	61
2/0 AWG	—	1	1	2	3	6	8	13	17	22	35	51
3/0 AWG	—	1	1	1	3	5	7	11	14	18	29	42
4/0 AWG	—	—	1	1	1	4	6	9	12	15	24	35
250 kcmil	—	—	1	1	1	3	4	7	10	12	20	28
300 kcmil	—	—	—	1	1	3	4	6	8	11	17	24
350 kcmil	—	—	—	1	1	1	3	5	7	9	15	21
400 kcmil	—	—	—	1	1	1	3	5	6	8	13	19
500 kcmil	—	—	—	1	1	1	2	4	5	7	11	16
600 kcmil	—	—	—	—	1	1	1	3	4	5	9	13
700 kcmil	—	—	—	—	1	1	1	3	4	5	8	11
750 kcmil	—	—	—	—	1	1	1	2	3	4	7	11
800 kcmil	—	—	—	—	—	1	1	2	3	4	7	10
900 kcmil	—	—	—	—	—	1	1	1	3	4	6	9
1000 kcmil	—	—	—	—	—	1	1	1	3	3	6	8

PVC Schedule 40 fill chart — XHHW / XHHW-2

Cross-linked polyethylene (XLPE) insulation, no nylon jacket. Standard for aluminum feeders and common for larger copper feeders. Slightly fatter than THHN in small sizes, slightly thinner above 4 AWG.

Maximum XHHW conductors in PVC Schedule 40 — 40% fill (53% for one wire, 31% for two)
Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"	5"	6"
14 AWG	8	14	24	42	57	94	135	209	280	361	568	822
12 AWG	6	11	18	32	44	72	103	160	215	277	436	631
10 AWG	4	8	13	24	32	54	77	119	160	206	325	470
8 AWG	2	4	7	13	18	30	43	66	89	115	181	261
6 AWG	1	3	5	10	13	22	32	49	66	85	134	193
4 AWG	1	1	4	7	9	16	23	35	48	61	97	140
3 AWG	1	1	3	6	8	13	19	30	40	52	82	118
2 AWG	1	1	3	5	7	11	16	25	34	44	69	99
1 AWG	—	1	1	3	5	8	12	19	25	32	51	74
1/0 AWG	—	1	1	3	4	7	10	16	21	27	43	62
2/0 AWG	—	1	1	2	3	6	8	13	17	23	36	52
3/0 AWG	—	1	1	1	3	5	7	11	14	19	30	43
4/0 AWG	—	—	1	1	1	4	6	9	12	15	24	35
250 kcmil	—	—	1	1	1	3	5	7	10	13	20	29
300 kcmil	—	—	—	1	1	3	4	6	8	11	17	25
350 kcmil	—	—	—	1	1	1	3	5	7	9	15	22
400 kcmil	—	—	—	1	1	1	3	5	6	8	13	19
500 kcmil	—	—	—	1	1	1	2	4	5	7	11	16
600 kcmil	—	—	—	—	1	1	1	3	4	5	9	13
700 kcmil	—	—	—	—	1	1	1	3	4	5	8	11
750 kcmil	—	—	—	—	—	1	1	2	3	4	7	11
800 kcmil	—	—	—	—	—	1	1	2	3	4	7	10
900 kcmil	—	—	—	—	—	1	1	1	3	4	6	9
1000 kcmil	—	—	—	—	—	1	1	1	3	3	6	8

PVC Schedule 40 fill chart — THW / THHW / TW

Older thick-wall thermoplastic insulation without a nylon jacket. Rarely installed new, but it is what you will find in many existing conduits, and it takes considerably more room than THHN.

Maximum THW conductors in PVC Schedule 40 — 40% fill (53% for one wire, 31% for two)
Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"	5"	6"
14 AWG	8	14	24	42	57	94	135	209	280	361	568	822
12 AWG	6	11	18	32	44	72	103	160	215	277	436	631
10 AWG	4	8	13	24	32	54	77	119	160	206	325	470
8 AWG	2	4	7	13	18	30	43	66	89	115	181	261
6 AWG	1	2	4	8	11	18	26	40	53	69	109	157
4 AWG	1	1	3	6	8	13	19	30	40	51	81	117
3 AWG	1	1	3	5	7	11	16	25	34	44	69	100
2 AWG	1	1	1	4	6	10	14	22	29	37	59	85
1 AWG	—	1	1	3	4	7	10	15	20	26	41	60
1/0 AWG	—	1	1	2	3	6	8	13	17	22	35	51
2/0 AWG	—	1	1	1	3	5	7	11	15	19	30	43
3/0 AWG	—	—	1	1	1	4	6	9	12	16	25	36
4/0 AWG	—	—	1	1	1	3	5	8	10	13	21	30
250 kcmil	—	—	—	1	1	3	4	6	8	11	17	25
300 kcmil	—	—	—	1	1	1	3	5	7	9	15	21
350 kcmil	—	—	—	1	1	1	3	5	6	8	13	19
400 kcmil	—	—	—	1	1	1	3	4	6	7	12	17
500 kcmil	—	—	—	—	1	1	1	3	5	6	10	14
600 kcmil	—	—	—	—	1	1	1	3	4	5	8	11
700 kcmil	—	—	—	—	—	1	1	2	3	4	7	10
750 kcmil	—	—	—	—	—	1	1	1	3	4	6	10
800 kcmil	—	—	—	—	—	1	1	1	3	4	6	9
900 kcmil	—	—	—	—	—	1	1	1	3	3	6	8
1000 kcmil	—	—	—	—	—	1	1	1	2	3	5	7

PVC Schedule 40 fill chart — RHH / RHW-2

Thermoset rubber-type insulation with an outer covering. The bulkiest of the common types; counts drop to roughly half of THHN in small conduit.

Maximum RHW conductors in PVC Schedule 40 — 40% fill (53% for one wire, 31% for two)
Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"	5"	6"
14 AWG	4	7	11	20	27	45	64	99	133	171	269	390
12 AWG	3	5	9	16	22	37	53	82	110	142	224	323
10 AWG	2	4	7	13	18	30	43	66	89	115	181	261
8 AWG	1	1	4	7	9	15	22	35	46	60	94	137
6 AWG	1	1	3	5	7	12	18	28	37	48	76	109
4 AWG	1	1	1	4	6	10	14	22	29	37	59	85
3 AWG	—	1	1	4	5	8	12	19	25	33	52	75
2 AWG	—	1	1	3	4	7	10	16	22	28	45	65
1 AWG	—	1	1	1	3	5	7	11	14	19	29	43
1/0 AWG	—	—	1	1	2	4	6	9	13	16	26	37
2/0 AWG	—	—	1	1	1	3	5	8	11	14	22	32
3/0 AWG	—	—	1	1	1	3	4	7	9	12	19	28
4/0 AWG	—	—	—	1	1	2	4	6	8	10	16	24
250 kcmil	—	—	—	1	1	1	3	4	6	8	12	18
300 kcmil	—	—	—	1	1	1	2	4	5	7	11	16
350 kcmil	—	—	—	—	1	1	1	3	5	6	10	14
400 kcmil	—	—	—	—	1	1	1	3	4	6	9	13
500 kcmil	—	—	—	—	1	1	1	3	4	5	8	11
600 kcmil	—	—	—	—	—	1	1	1	3	4	6	9
700 kcmil	—	—	—	—	—	1	1	1	3	3	6	8
750 kcmil	—	—	—	—	—	1	1	1	2	3	5	8
800 kcmil	—	—	—	—	—	1	1	1	2	3	5	7
900 kcmil	—	—	—	—	—	1	1	1	1	3	5	7
1000 kcmil	—	—	—	—	—	—	1	1	1	3	4	6

PVC Schedule 40 internal diameter and area

PVC Schedule 40 internal dimensions and allowable fill area
Trade size	Metric designator	Internal dia. (in)	Total area (in²)	1 wire — 53%	2 wires — 31%	Over 2 — 40%	Nipple — 60%
1/2"	16	0.602	0.285	0.151	0.088	0.114	0.171
3/4"	21	0.804	0.508	0.269	0.157	0.203	0.305
1"	27	1.029	0.832	0.441	0.258	0.333	0.499
1-1/4"	35	1.360	1.453	0.770	0.450	0.581	0.872
1-1/2"	41	1.590	1.986	1.053	0.616	0.794	1.192
2"	53	2.047	3.291	1.744	1.020	1.316	1.975
2-1/2"	63	2.445	4.695	2.488	1.455	1.878	2.817
3"	78	3.042	7.268	3.852	2.253	2.907	4.361
3-1/2"	91	3.521	9.737	5.161	3.018	3.895	5.842
4"	103	3.998	12.554	6.654	3.892	5.022	7.532
5"	129	5.016	19.761	10.473	6.126	7.904	11.857
6"	155	6.031	28.567	15.141	8.856	11.427	17.140

Fill limits that apply

Allowable conduit fill (Chapter 9, Table 1 and its notes)
Conductors in the raceway	Maximum fill	Why
1	53%	A single conductor cannot jam, so more of the area can be used.
2	31%	Two conductors lie side by side and wedge easily in bends, so the limit is lowest.
3 or more	40%	The everyday limit. Leaves room to pull and for heat to escape.
Nipple ≤ 24 in.	60%	Short sections between boxes or enclosures; derating for conductor count does not apply either.

Frequently asked questions

How many #12 wires can I put in 1/2-inch PVC Schedule 40?

8 conductors of 12 AWG THHN/THWN-2, or 6 of the thicker THW. In 3/4-inch PVC Schedule 40 the count rises to 15 THHN.

How many #10 wires fit in 1/2-inch PVC Schedule 40?

5 conductors of 10 AWG THHN in 1/2-inch, and 9 in 3/4-inch.

What is the inside diameter of 3/4-inch PVC Schedule 40?

0.804 inches, giving a total internal area of 0.508 in² and 0.203 in² of usable area at 40% fill.

What is the largest wire that fits in 6-inch PVC Schedule 40?

6-inch PVC Schedule 40 holds 16 conductors of 500 kcmil THHN or 8 of 1000 kcmil.

NECTables.com is an independent reference and is not affiliated with, endorsed by, or a substitute for the National Fire Protection Association (NFPA). NEC® and National Electrical Code® are registered trademarks of the NFPA. Values shown are commonly published engineering data and independent calculations based on the methods of NFPA 70; they are not a reproduction of the Code. Always confirm against the edition adopted in your jurisdiction, including local amendments, and consult a licensed electrician or engineer before doing electrical work.