Conduit Fill Chart & Calculator

Free NEC conduit fill calculator with full fill charts. Enter your wires to get the fill percentage and the minimum conduit size for EMT, PVC, RMC, IMC, ENT, FMC and LFMC, plus how many wires fit in each trade size (Chapter 9, Tables 1, 4 and 5).

NEC edition

Inputs

Conduit type

Trade size

Insulation type

Conduit nipple (24 in. or less)

Conductors in Conduit

Conductor 1 — size

Conductor 1 — qty

wires

Conductor 2 — size

Conductor 2 — qty

wires

Conductor 3 — size

Conductor 3 — qty

wires

Conductor 4 — size

Conductor 4 — qty

wires

Conductor 5 — size

Conductor 5 — qty

wires

How it works & the NEC rules behind it

Quick answer: NEC Chapter 9, Table 1 limits the wires in a conduit to 40% of its internal area for 3 or more conductors, 31% for 2 conductors and 53% for 1 conductor. Add up the Table 5 area of every wire (grounds included), then pick the smallest conduit whose Table 4 area at that percentage is at least as large. The calculator above does it in one step, and the conduit fill chart and wires-per-conduit tables below give the answers for every size.

Jump to a conduit (pipe) fill chart: Quick lookup (all types) · EMT · PVC Sch 40 · PVC Sch 80 · Rigid (RMC) · IMC · ENT · FMC · LFMC · XHHW wire · Fill areas by size

The National Electrical Code regulates the volume of conductors inside a raceway to prevent excessive heat buildup and avoid damaging conductor insulation during pulling operations.

NEC Chapter 9 Table 1 Fill Rules:

1 Conductor: Maximum allowable fill is 53% of total interior conduit cross-sectional area.
2 Conductors: Maximum allowable fill is 31% of total interior conduit area (lower to prevent jamming / wedging).
3 or More Conductors: Maximum allowable fill is 40% of total interior conduit area.
Conduit Nipples (§310.15(C)(1) & Chapter 9 Note 4): Where conduit or tubing does not exceed 24 inches (600 mm) in length, raceway fill can be increased to 60% and bundling ampacity derating does not apply. Choose "Yes" under Conduit nipple in the calculator to use this limit.

Using the calculator

Pick the conduit type (EMT, PVC Schedule 40, RMC and so on) and your trade size.
Choose the wire insulation. THHN/THWN-2 and XHHW have different Table 5 areas, so pick the one on your wire.
Enter each wire size and how many you are pulling. Include the equipment grounding conductor and any neutral. You can mix up to five sizes.
Press Calculate. You get the fill percentage, a pass or fail against the limit, and the minimum conduit size for that raceway type.

Related conduit guides

Formulas & equations

Total Wire Area = Σ (Wire Count × Individual Conductor Area from Table 5) Max Allowable Area = Conduit Internal Area (Table 4) × (Max Fill % / 100) % Fill Used = (Total Wire Area / Conduit Internal Area) × 100% Wires That Fit = Conduit Internal Area × 0.40 ÷ One Wire Area (round up at .8 or more, Note 7)

Where:
• Conductor cross-sectional dimensions include insulation from NEC Chapter 9, Table 5.
• Internal raceway dimensions are sourced from NEC Chapter 9, Table 4.
• The last formula applies to 3 or more conductors of the same size; use 0.53 for one wire and 0.31 for two.

NEC reference table

Every chart below is generated from the same NEC Chapter 9 data as the calculator, so the numbers always match. Wire counts come first; the fill areas for each trade size follow.

Conduit fill chart: quick lookup by trade size (THHN/THWN-2)

Find your trade size, then read across for the maximum number of same-size THHN/THWN-2 wires in EMT, IMC, rigid, flexible metal and PVC Schedule 40 conduit at 40% fill. Scroll the table sideways for larger wire sizes.

Trade size	Conduit	#14	#12	#10	#8	#6	#4	#3	#2	#1	#1/0	#2/0	#3/0	#4/0	250 kcmil	300 kcmil	350 kcmil	400 kcmil	500 kcmil	600 kcmil	700 kcmil	750 kcmil
1/2"	EMT	12	9	5	3	2	1	1	1	1	1	–	–	–	–	–	–	–	–	–	–	–
	IMC	14	10	6	3	2	1	1	1	1	1	1	–	–	–	–	–	–	–	–	–	–
	RMC (rigid)	13	9	6	3	2	1	1	1	1	1	–	–	–	–	–	–	–	–	–	–	–
	FMC	13	9	6	3	2	1	1	1	1	1	–	–	–	–	–	–	–	–	–	–	–
	PVC Schedule 40	11	8	5	3	1	1	1	1	1	1	–	–	–	–	–	–	–	–	–	–	–
3/4"	EMT	22	16	10	6	4	2	1	1	1	1	1	1	1	–	–	–	–	–	–	–	–
	IMC	24	17	11	6	4	3	2	1	1	1	1	1	1	–	–	–	–	–	–	–	–
	RMC (rigid)	22	16	10	6	4	2	1	1	1	1	1	1	1	–	–	–	–	–	–	–	–
	FMC	22	16	10	6	4	2	1	1	1	1	1	1	1	–	–	–	–	–	–	–	–
	PVC Schedule 40	21	15	9	5	4	2	1	1	1	1	1	1	1	–	–	–	–	–	–	–	–
1"	EMT	35	26	16	9	7	4	3	3	1	1	1	1	1	1	1	1	–	–	–	–	–
	IMC	39	29	18	10	7	4	4	3	2	1	1	1	1	1	1	1	1	–	–	–	–
	RMC (rigid)	36	26	17	9	7	4	3	3	1	1	1	1	1	1	1	1	1	–	–	–	–
	FMC	33	24	15	9	6	4	3	3	1	1	1	1	1	1	1	1	–	–	–	–	–
	PVC Schedule 40	34	25	15	9	6	4	3	3	1	1	1	1	1	1	1	1	–	–	–	–	–
1-1/4"	EMT	61	45	28	16	12	7	6	5	4	3	2	1	1	1	1	1	1	1	1	1	–
	IMC	68	49	31	18	13	8	6	5	4	3	3	2	1	1	1	1	1	1	1	1	1
	RMC (rigid)	63	46	29	16	12	7	6	5	4	3	2	1	1	1	1	1	1	1	1	1	–
	FMC	52	38	24	14	10	6	5	4	3	2	1	1	1	1	1	1	1	1	–	–	–
	PVC Schedule 40	60	43	27	16	11	7	6	5	3	3	2	1	1	1	1	1	1	1	1	–	–
1-1/2"	EMT	84	61	38	22	16	10	8	7	5	4	3	3	2	1	1	1	1	1	1	1	1
	IMC	91	67	42	24	17	11	9	7	5	4	4	3	2	1	1	1	1	1	1	1	1
	RMC (rigid)	85	62	39	22	16	10	8	7	5	4	3	3	2	1	1	1	1	1	1	1	1
	FMC	76	56	35	20	14	9	7	6	4	4	3	2	1	1	1	1	1	1	1	1	1
	PVC Schedule 40	82	59	37	21	15	9	8	7	5	4	3	3	2	1	1	1	1	1	1	1	1
2"	EMT	138	101	63	36	26	16	13	11	8	7	6	5	4	3	3	2	1	1	1	1	1
	IMC	149	109	69	39	28	17	15	12	9	8	6	5	4	3	3	2	2	1	1	1	1
	RMC (rigid)	140	102	64	37	27	16	14	11	8	7	6	5	4	3	3	2	2	1	1	1	1
	FMC	135	98	62	35	25	16	13	11	8	7	6	5	4	3	3	2	1	1	1	1	1
	PVC Schedule 40	135	99	62	36	26	16	13	11	8	7	6	5	4	3	3	2	1	1	1	1	1
2-1/2"	EMT	241	176	111	64	46	28	24	20	15	12	10	8	7	6	5	4	4	3	2	2	1
	IMC	211	154	97	56	40	25	21	17	13	11	9	7	6	5	4	4	3	3	2	1	1
	RMC (rigid)	200	146	92	53	38	23	20	17	12	10	8	7	6	5	4	3	3	2	1	1	1
	FMC	202	147	93	53	38	24	20	17	12	10	9	7	6	5	4	3	3	2	1	1	1
	PVC Schedule 40	193	141	89	51	37	22	19	16	12	10	8	7	6	4	4	3	3	2	1	1	1
3"	EMT	364	266	167	96	69	43	36	30	22	19	16	13	11	9	7	6	6	5	4	3	3
	IMC	326	238	150	86	62	38	32	27	20	17	14	12	9	8	7	6	5	4	3	3	3
	RMC (rigid)	309	225	142	82	59	36	31	26	19	16	13	11	9	7	6	5	5	4	3	3	3
	FMC	291	212	134	77	55	34	29	24	18	15	12	10	8	7	6	5	5	4	3	3	2
	PVC Schedule 40	299	218	137	79	57	35	30	25	18	15	13	11	9	7	6	5	5	4	3	3	2
3-1/2"	EMT	476	347	219	126	91	56	47	40	29	25	20	17	14	11	10	9	8	6	5	4	4
	IMC	436	318	200	115	83	51	43	36	27	23	19	16	13	10	9	8	7	6	5	4	4
	RMC (rigid)	412	301	189	109	79	48	41	34	25	21	18	15	12	10	8	7	7	5	4	4	4
	FMC	396	289	182	105	76	46	39	33	24	20	17	14	12	9	8	7	6	5	4	4	3
	PVC Schedule 40	401	293	184	106	77	47	40	33	25	21	17	14	12	10	8	7	6	5	4	4	3
4"	EMT	608	443	279	161	116	71	60	51	37	32	26	22	18	15	13	11	10	8	7	6	5
	IMC	562	410	258	149	107	66	56	47	35	29	24	20	17	13	12	10	9	7	6	5	5
	RMC (rigid)	531	387	244	140	101	62	53	44	33	27	23	19	16	13	11	10	8	7	6	5	5
	FMC	518	378	238	137	99	61	51	43	32	27	22	18	15	12	11	9	8	7	5	5	4
	PVC Schedule 40	517	377	238	137	99	61	51	43	32	27	22	18	15	12	11	9	8	7	5	5	4
5"	RMC (rigid)	833	608	383	221	159	98	83	70	51	43	36	30	25	20	17	15	13	11	9	8	7
5"	PVC Schedule 40	815	594	374	216	156	96	81	68	50	42	35	29	24	20	17	15	13	11	9	8	7
6"	RMC (rigid)	1202	877	552	318	230	141	120	100	74	63	52	43	36	29	25	22	20	16	13	11	11
6"	PVC Schedule 40	1178	859	541	312	225	138	117	98	73	61	51	42	35	28	24	21	19	16	13	11	11

Conduit wire fill chart: how many THHN/THWN-2 wires fit (40% fill)

Maximum number of same-size THHN/THWN-2 conductors per conduit, worked the same way as NEC Annex C (Tables C.1 to C.12). Mixed sizes: add the Table 5 areas, or use the calculator. A dash means not even one wire of that size is permitted.

EMT conduit fill chart (THHN wires per conduit)

Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
#14	12	22	35	61	84	138	241	364	476	608
#12	9	16	26	45	61	101	176	266	347	443
#10	5	10	16	28	38	63	111	167	219	279
#8	3	6	9	16	22	36	64	96	126	161
#6	2	4	7	12	16	26	46	69	91	116
#4	1	2	4	7	10	16	28	43	56	71
#3	1	1	3	6	8	13	24	36	47	60
#2	1	1	3	5	7	11	20	30	40	51
#1	1	1	1	4	5	8	15	22	29	37
#1/0	1	1	1	3	4	7	12	19	25	32
#2/0	–	1	1	2	3	6	10	16	20	26
#3/0	–	1	1	1	3	5	8	13	17	22
#4/0	–	1	1	1	2	4	7	11	14	18
250 kcmil	–	–	1	1	1	3	6	9	11	15
300 kcmil	–	–	1	1	1	3	5	7	10	13
350 kcmil	–	–	1	1	1	2	4	6	9	11
400 kcmil	–	–	–	1	1	1	4	6	8	10
500 kcmil	–	–	–	1	1	1	3	5	6	8
600 kcmil	–	–	–	1	1	1	2	4	5	7
700 kcmil	–	–	–	1	1	1	2	3	4	6
750 kcmil	–	–	–	–	1	1	1	3	4	5

PVC Schedule 40 conduit fill chart (THHN wires per conduit)

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	11	21	34	60	82	135	193	299	401	517	815	1178
#12	8	15	25	43	59	99	141	218	293	377	594	859
#10	5	9	15	27	37	62	89	137	184	238	374	541
#8	3	5	9	16	21	36	51	79	106	137	216	312
#6	1	4	6	11	15	26	37	57	77	99	156	225
#4	1	2	4	7	9	16	22	35	47	61	96	138
#3	1	1	3	6	8	13	19	30	40	51	81	117
#2	1	1	3	5	7	11	16	25	33	43	68	98
#1	1	1	1	3	5	8	12	18	25	32	50	73
#1/0	1	1	1	3	4	7	10	15	21	27	42	61
#2/0	–	1	1	2	3	6	8	13	17	22	35	51
#3/0	–	1	1	1	3	5	7	11	14	18	29	42
#4/0	–	1	1	1	2	4	6	9	12	15	24	35
250 kcmil	–	–	1	1	1	3	4	7	10	12	20	28
300 kcmil	–	–	1	1	1	3	4	6	8	11	17	24
350 kcmil	–	–	1	1	1	2	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	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

PVC Schedule 80 conduit fill chart (THHN wires per conduit)

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	9	17	28	51	70	118	170	265	358	464	736	1055
#12	6	12	20	37	51	86	124	193	261	338	537	770
#10	4	7	13	23	32	54	78	122	164	213	338	485
#8	2	4	7	13	18	31	45	70	95	123	195	279
#6	1	3	5	9	13	22	32	51	68	89	141	202
#4	1	1	3	6	8	14	20	31	42	54	86	124
#3	1	1	3	5	7	12	17	26	35	46	73	105
#2	1	1	2	4	6	10	14	22	30	39	61	88
#1	–	1	1	3	4	7	10	16	22	29	45	65
#1/0	–	1	1	2	3	6	9	14	18	24	38	55
#2/0	–	1	1	1	3	5	7	11	15	20	32	46
#3/0	–	1	1	1	2	4	6	9	13	17	26	38
#4/0	–	–	1	1	1	3	5	8	10	14	22	31
250 kcmil	–	–	1	1	1	3	4	6	8	11	18	25
300 kcmil	–	–	–	1	1	2	3	5	7	9	15	22
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	2	3	5	6	10	14
600 kcmil	–	–	–	–	1	1	1	3	4	5	8	12
700 kcmil	–	–	–	–	1	1	1	2	3	4	7	10
750 kcmil	–	–	–	–	1	1	1	2	3	4	7	9

Rigid (RMC) conduit fill chart (THHN wires per conduit)

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	13	22	36	63	85	140	200	309	412	531	833	1202
#12	9	16	26	46	62	102	146	225	301	387	608	877
#10	6	10	17	29	39	64	92	142	189	244	383	552
#8	3	6	9	16	22	37	53	82	109	140	221	318
#6	2	4	7	12	16	27	38	59	79	101	159	230
#4	1	2	4	7	10	16	23	36	48	62	98	141
#3	1	1	3	6	8	14	20	31	41	53	83	120
#2	1	1	3	5	7	11	17	26	34	44	70	100
#1	1	1	1	4	5	8	12	19	25	33	51	74
#1/0	1	1	1	3	4	7	10	16	21	27	43	63
#2/0	–	1	1	2	3	6	8	13	18	23	36	52
#3/0	–	1	1	1	3	5	7	11	15	19	30	43
#4/0	–	1	1	1	2	4	6	9	12	16	25	36
250 kcmil	–	–	1	1	1	3	5	7	10	13	20	29
300 kcmil	–	–	1	1	1	3	4	6	8	11	17	25
350 kcmil	–	–	1	1	1	2	3	5	7	10	15	22
400 kcmil	–	–	1	1	1	2	3	5	7	8	13	20
500 kcmil	–	–	–	1	1	1	2	4	5	7	11	16
600 kcmil	–	–	–	1	1	1	1	3	4	6	9	13
700 kcmil	–	–	–	1	1	1	1	3	4	5	8	11
750 kcmil	–	–	–	–	1	1	1	3	4	5	7	11

IMC conduit fill chart (THHN wires per conduit)

Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
#14	14	24	39	68	91	149	211	326	436	562
#12	10	17	29	49	67	109	154	238	318	410
#10	6	11	18	31	42	69	97	150	200	258
#8	3	6	10	18	24	39	56	86	115	149
#6	2	4	7	13	17	28	40	62	83	107
#4	1	3	4	8	11	17	25	38	51	66
#3	1	2	4	6	9	15	21	32	43	56
#2	1	1	3	5	7	12	17	27	36	47
#1	1	1	2	4	5	9	13	20	27	35
#1/0	1	1	1	3	4	8	11	17	23	29
#2/0	1	1	1	3	4	6	9	14	19	24
#3/0	–	1	1	2	3	5	7	12	16	20
#4/0	–	1	1	1	2	4	6	9	13	17
250 kcmil	–	–	1	1	1	3	5	8	10	13
300 kcmil	–	–	1	1	1	3	4	7	9	12
350 kcmil	–	–	1	1	1	2	4	6	8	10
400 kcmil	–	–	1	1	1	2	3	5	7	9
500 kcmil	–	–	–	1	1	1	3	4	6	7
600 kcmil	–	–	–	1	1	1	2	3	5	6
700 kcmil	–	–	–	1	1	1	1	3	4	5
750 kcmil	–	–	–	1	1	1	1	3	4	5

ENT (flexible PVC) conduit fill chart (THHN wires per conduit)

Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"
#14	11	21	34	60	82	135
#12	8	15	25	43	59	99
#10	5	9	15	27	37	62
#8	3	5	9	16	21	36
#6	1	4	6	11	15	26
#4	1	2	4	7	9	16
#3	1	1	3	6	8	13
#2	1	1	3	5	7	11
#1	1	1	1	3	5	8
#1/0	1	1	1	3	4	7
#2/0	–	1	1	2	3	6
#3/0	–	1	1	1	3	5
#4/0	–	1	1	1	2	4
250 kcmil	–	–	1	1	1	3
300 kcmil	–	–	1	1	1	3
350 kcmil	–	–	1	1	1	2
400 kcmil	–	–	–	1	1	1
500 kcmil	–	–	–	1	1	1
600 kcmil	–	–	–	1	1	1
700 kcmil	–	–	–	–	1	1
750 kcmil	–	–	–	–	1	1

Flexible metal conduit (FMC) fill chart (THHN wires per conduit)

Wire size	3/8"	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
#14	4	13	22	33	52	76	135	202	291	396	518
#12	3	9	16	24	38	56	98	147	212	289	378
#10	1	6	10	15	24	35	62	93	134	182	238
#8	1	3	6	9	14	20	35	53	77	105	137
#6	1	2	4	6	10	14	25	38	55	76	99
#4	–	1	2	4	6	9	16	24	34	46	61
#3	–	1	1	3	5	7	13	20	29	39	51
#2	–	1	1	3	4	6	11	17	24	33	43
#1	–	1	1	1	3	4	8	12	18	24	32
#1/0	–	1	1	1	2	4	7	10	15	20	27
#2/0	–	–	1	1	1	3	6	9	12	17	22
#3/0	–	–	1	1	1	2	5	7	10	14	18
#4/0	–	–	1	1	1	1	4	6	8	12	15
250 kcmil	–	–	–	1	1	1	3	5	7	9	12
300 kcmil	–	–	–	1	1	1	3	4	6	8	11
350 kcmil	–	–	–	1	1	1	2	3	5	7	9
400 kcmil	–	–	–	–	1	1	1	3	5	6	8
500 kcmil	–	–	–	–	1	1	1	2	4	5	7
600 kcmil	–	–	–	–	–	1	1	1	3	4	5
700 kcmil	–	–	–	–	–	1	1	1	3	4	5
750 kcmil	–	–	–	–	–	1	1	1	2	3	4

Liquidtight (LFMC) conduit fill chart (THHN wires per conduit)

Wire size	3/8"	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
#14	8	13	22	36	63	81	134	201	308	401	523
#12	5	9	16	26	46	59	97	146	225	292	381
#10	3	6	10	16	29	37	61	92	141	184	240
#8	1	3	6	9	16	21	35	53	81	106	138
#6	1	2	4	7	12	15	25	38	59	76	100
#4	1	1	2	4	7	9	15	23	36	47	61
#3	1	1	1	3	6	8	13	20	30	40	52
#2	1	1	1	3	5	7	11	17	26	33	44
#1	–	1	1	1	4	5	8	12	19	25	32
#1/0	–	1	1	1	3	4	7	10	16	21	27
#2/0	–	–	1	1	2	3	6	8	13	17	23
#3/0	–	–	1	1	1	3	5	7	11	14	19
#4/0	–	–	1	1	1	2	4	6	9	12	15
250 kcmil	–	–	–	1	1	1	3	5	7	10	12
300 kcmil	–	–	–	1	1	1	3	4	6	8	11
350 kcmil	–	–	–	1	1	1	2	3	5	7	9
400 kcmil	–	–	–	–	1	1	1	3	5	6	8
500 kcmil	–	–	–	–	1	1	1	2	4	5	7
600 kcmil	–	–	–	–	1	1	1	1	3	4	6
700 kcmil	–	–	–	–	1	1	1	1	3	4	5
750 kcmil	–	–	–	–	–	1	1	1	3	3	5

XHHW-2 conduit fill chart

XHHW-2 has a thicker insulation than THHN in the small sizes (#14 to #6), so fewer wires fit. From #4 up the two are almost the same size.

EMT: XHHW-2 wires per conduit

Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
#14	8	15	25	43	58	96	168	254	332	424
#12	6	11	19	33	45	74	129	195	255	326
#10	5	8	14	24	33	55	96	145	190	243
#8	2	5	8	13	18	30	53	81	105	135
#6	1	3	6	10	14	22	39	60	78	100
#4	1	2	4	7	10	16	28	43	56	72
#3	1	1	3	6	8	14	24	36	48	61
#2	1	1	3	5	7	11	20	31	40	51
#1	1	1	1	4	5	8	15	23	30	38
#1/0	1	1	1	3	4	7	13	19	25	32
#2/0	–	1	1	2	3	6	10	16	21	27
#3/0	–	1	1	1	3	5	9	13	17	22
#4/0	–	1	1	1	2	4	7	11	14	18
250 kcmil	–	–	1	1	1	3	6	9	12	15
300 kcmil	–	–	1	1	1	3	5	8	10	13
350 kcmil	–	–	1	1	1	2	4	7	9	11
400 kcmil	–	–	–	1	1	1	4	6	8	10
500 kcmil	–	–	–	1	1	1	3	5	6	8
600 kcmil	–	–	–	1	1	1	2	4	5	6
700 kcmil	–	–	–	–	1	1	2	3	4	6
750 kcmil	–	–	–	–	1	1	1	3	4	5

PVC Schedule 40: XHHW-2 wires per conduit

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	8	14	24	42	57	94	135	209	280	361	568	822
#12	6	11	18	32	44	72	103	160	215	277	436	631
#10	4	8	13	24	32	54	77	119	160	206	325	470
#8	2	4	7	13	18	30	43	66	89	115	181	261
#6	1	3	5	10	13	22	32	49	66	85	134	193
#4	1	2	4	7	9	16	23	35	48	61	97	140
#3	1	1	3	6	8	13	19	30	40	52	82	118
#2	1	1	3	5	7	11	16	25	34	44	69	99
#1	1	1	1	3	5	8	12	19	25	32	51	74
#1/0	1	1	1	3	4	7	10	16	21	27	43	62
#2/0	–	1	1	2	3	6	8	13	17	23	36	52
#3/0	–	1	1	1	3	5	7	11	14	19	30	43
#4/0	–	1	1	1	2	4	6	9	12	15	24	35
250 kcmil	–	–	1	1	1	3	5	7	10	13	20	29
300 kcmil	–	–	1	1	1	3	4	6	8	11	17	25
350 kcmil	–	–	1	1	1	2	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	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

RMC (rigid): XHHW-2 wires per conduit

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	9	15	25	44	59	98	140	215	288	370	581	839
#12	7	12	19	33	45	75	107	165	221	284	446	644
#10	5	9	14	25	34	56	80	123	164	212	332	480
#8	3	5	8	14	19	31	44	68	91	118	185	267
#6	1	3	6	10	14	23	33	51	68	87	137	197
#4	1	2	4	7	10	16	24	37	49	63	99	143
#3	1	1	3	6	8	14	20	31	41	53	84	121
#2	1	1	3	5	7	12	17	26	35	45	70	101
#1	1	1	1	4	5	9	12	19	26	33	52	76
#1/0	1	1	1	3	4	7	10	16	22	28	44	64
#2/0	–	1	1	2	3	6	9	13	18	23	37	53
#3/0	–	1	1	1	3	5	7	11	15	19	30	44
#4/0	–	1	1	1	2	4	6	9	12	16	25	36
250 kcmil	–	–	1	1	1	3	5	7	10	13	20	30
300 kcmil	–	–	1	1	1	3	4	6	9	11	18	25
350 kcmil	–	–	1	1	1	2	3	6	7	10	15	22
400 kcmil	–	–	1	1	1	2	3	5	7	9	14	20
500 kcmil	–	–	–	1	1	1	2	4	5	7	11	16
600 kcmil	–	–	–	1	1	1	1	3	4	6	9	13
700 kcmil	–	–	–	1	1	1	1	3	4	5	8	11
750 kcmil	–	–	–	–	1	1	1	3	4	5	7	11

*Counts follow the NEC Annex C method for conductors of the same size: Table 4 area × Table 1 percentage ÷ Table 5 area, rounded up to the next whole wire when the decimal is 0.8 or more (Chapter 9, Note 7). Where only 1 or 2 wires fit, the 53% and 31% limits apply. For mixed wire sizes, Note 7 does not apply, so use the calculator.

Conduit fill area chart: 53%, 31%, 40% and 60% limits by size

Areas are in square inches. "Nipple" is a raceway 24 inches or shorter (60% fill).

Electrical Metallic Tubing (Art. 358)

Trade size	Internal dia. (in)	Total area (in²)	1 wire, 53% (in²)	2 wires, 31% (in²)	3+ wires, 40% (in²)	Nipple, 60% (in²)
1/2"	0.622	0.304	0.161	0.094	0.122	0.182
3/4"	0.824	0.533	0.282	0.165	0.213	0.320
1"	1.049	0.864	0.458	0.268	0.346	0.518
1-1/4"	1.380	1.496	0.793	0.464	0.598	0.898
1-1/2"	1.610	2.036	1.079	0.631	0.814	1.222
2"	2.067	3.356	1.779	1.040	1.342	2.014
2-1/2"	2.731	5.858	3.105	1.816	2.343	3.515
3"	3.356	8.846	4.688	2.742	3.538	5.308
3-1/2"	3.834	11.545	6.119	3.579	4.618	6.927
4"	4.334	14.753	7.819	4.573	5.901	8.852

Rigid Metal Conduit (Art. 344)

Trade size	Internal dia. (in)	Total area (in²)	1 wire, 53% (in²)	2 wires, 31% (in²)	3+ wires, 40% (in²)	Nipple, 60% (in²)
1/2"	0.632	0.314	0.166	0.097	0.126	0.188
3/4"	0.836	0.549	0.291	0.170	0.220	0.329
1"	1.063	0.887	0.470	0.275	0.355	0.532
1-1/4"	1.394	1.526	0.809	0.473	0.610	0.916
1-1/2"	1.624	2.071	1.098	0.642	0.828	1.243
2"	2.083	3.408	1.806	1.056	1.363	2.045
2-1/2"	2.489	4.866	2.579	1.508	1.946	2.920
3"	3.090	7.499	3.974	2.325	3.000	4.499
3-1/2"	3.570	10.010	5.305	3.103	4.004	6.006
4"	4.050	12.882	6.827	3.993	5.153	7.729
5"	5.073	20.212	10.712	6.266	8.085	12.127
6"	6.093	29.158	15.454	9.039	11.663	17.495

Intermediate Metal Conduit (Art. 342)

Trade size	Internal dia. (in)	Total area (in²)	1 wire, 53% (in²)	2 wires, 31% (in²)	3+ wires, 40% (in²)	Nipple, 60% (in²)
1/2"	0.660	0.342	0.181	0.106	0.137	0.205
3/4"	0.864	0.586	0.311	0.182	0.234	0.352
1"	1.105	0.959	0.508	0.297	0.384	0.575
1-1/4"	1.448	1.647	0.873	0.511	0.659	0.988
1-1/2"	1.683	2.225	1.179	0.690	0.890	1.335
2"	2.150	3.631	1.924	1.126	1.452	2.179
2-1/2"	2.557	5.135	2.722	1.592	2.054	3.081
3"	3.176	7.922	4.199	2.456	3.169	4.753
3-1/2"	3.671	10.584	5.610	3.281	4.234	6.350
4"	4.166	13.631	7.224	4.226	5.452	8.179

Rigid PVC Conduit, Schedule 40 / HDPE (Art. 352, 353)

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

Rigid PVC Conduit, Schedule 80 (Art. 352)

Trade size	Internal dia. (in)	Total area (in²)	1 wire, 53% (in²)	2 wires, 31% (in²)	3+ wires, 40% (in²)	Nipple, 60% (in²)
1/2"	0.526	0.217	0.115	0.067	0.087	0.130
3/4"	0.722	0.409	0.217	0.127	0.164	0.245
1"	0.936	0.688	0.365	0.213	0.275	0.413
1-1/4"	1.255	1.237	0.656	0.383	0.495	0.742
1-1/2"	1.476	1.711	0.907	0.530	0.684	1.027
2"	1.913	2.874	1.523	0.891	1.150	1.724
2-1/2"	2.290	4.119	2.183	1.277	1.648	2.471
3"	2.864	6.442	3.414	1.997	2.577	3.865
3-1/2"	3.326	8.688	4.605	2.693	3.475	5.213
4"	3.786	11.258	5.967	3.490	4.503	6.755
5"	4.768	17.855	9.463	5.535	7.142	10.713
6"	5.709	25.598	13.567	7.935	10.239	15.359

Electrical Nonmetallic Tubing (Art. 362)

Trade size	Internal dia. (in)	Total area (in²)	1 wire, 53% (in²)	2 wires, 31% (in²)	3+ wires, 40% (in²)	Nipple, 60% (in²)
1/2"	0.602	0.285	0.151	0.088	0.114	0.171
3/4"	0.804	0.508	0.269	0.157	0.203	0.305
1"	1.029	0.832	0.441	0.258	0.333	0.499
1-1/4"	1.360	1.453	0.770	0.450	0.581	0.872
1-1/2"	1.590	1.986	1.053	0.616	0.794	1.192
2"	2.047	3.291	1.744	1.020	1.316	1.975

Flexible Metal Conduit (Art. 348)

Trade size	Internal dia. (in)	Total area (in²)	1 wire, 53% (in²)	2 wires, 31% (in²)	3+ wires, 40% (in²)	Nipple, 60% (in²)
3/8"	0.384	0.116	0.061	0.036	0.046	0.070
1/2"	0.635	0.317	0.168	0.098	0.127	0.190
3/4"	0.824	0.533	0.282	0.165	0.213	0.320
1"	1.020	0.817	0.433	0.253	0.327	0.490
1-1/4"	1.275	1.277	0.677	0.396	0.511	0.766
1-1/2"	1.538	1.858	0.985	0.576	0.743	1.115
2"	2.040	3.269	1.733	1.013	1.308	1.961
2-1/2"	2.500	4.909	2.602	1.522	1.964	2.945
3"	3.000	7.069	3.747	2.191	2.828	4.241
3-1/2"	3.500	9.621	5.099	2.983	3.848	5.773
4"	4.000	12.566	6.660	3.895	5.026	7.540

Liquidtight Flexible Metal Conduit (Art. 350)

Trade size	Internal dia. (in)	Total area (in²)	1 wire, 53% (in²)	2 wires, 31% (in²)	3+ wires, 40% (in²)	Nipple, 60% (in²)
3/8"	0.494	0.192	0.102	0.060	0.077	0.115
1/2"	0.632	0.314	0.166	0.097	0.126	0.188
3/4"	0.830	0.541	0.287	0.168	0.216	0.325
1"	1.054	0.873	0.463	0.271	0.349	0.524
1-1/4"	1.395	1.528	0.810	0.474	0.611	0.917
1-1/2"	1.588	1.981	1.050	0.614	0.792	1.189
2"	2.033	3.246	1.720	1.006	1.298	1.948
2-1/2"	2.493	4.881	2.587	1.513	1.952	2.929
3"	3.085	7.475	3.962	2.317	2.990	4.485
3-1/2"	3.520	9.731	5.157	3.017	3.892	5.839
4"	4.020	12.692	6.727	3.935	5.077	7.615

*Source: NEC Chapter 9, Table 1 (fill percentages) and Table 4 (dimensions and percent area of conduit and tubing). Use the 40% column for most installations.

Worked example, step by step

Example Calculation: Sizing EMT for (4) #3/0 THHN + (1) #6 Ground

Scenario: You are pulling 4 circuit conductors (#3/0 AWG THHN) and 1 equipment grounding conductor (#6 AWG THHN) in Electrical Metallic Tubing (EMT).

Step 1 (Find Conductor Areas from Table 5):
• (4) #3/0 THHN = 4 × 0.2679 in² = 1.0716 in²
• (1) #6 THHN = 1 × 0.0507 in² = 0.0507 in²
• Total Conductor Area = 1.1223 in²
Step 2 (Determine Fill Limit): Since count is 5 conductors (3+), max fill is 40%.
Step 3 (Table 4 Comparison):
• 1-1/2" EMT (40% area = 0.814 in²) → 1.1223 > 0.814 (FAILS)
• 2" EMT (40% area = 1.342 in²) → 1.1223 ≤ 1.342 (PASSES at 33.4% fill)
Result: Install minimum 2-inch EMT Conduit.

Frequently asked questions

In 1/2-inch EMT at the 40% limit you can pull up to 12 #14, 9 #12, 5 #10 or 3 #8 THHN conductors of the same size. In 3/4-inch EMT the counts are 22, 16, 10 and 6. In 1-inch EMT they are 35, 26, 16 and 9. Mixed sizes need the area method: add each wire's Table 5 area and compare the total with 40% of the conduit area.

In 3/4-inch conduit, #12 THHN fits up to 16 wires in EMT, 16 in rigid (RMC), 17 in IMC, 15 in PVC Schedule 40 and 12 in PVC Schedule 80 at 40% fill. PVC Schedule 80 holds fewer wires because its walls are thicker.

Look up each conductor's area in Chapter 9, Table 5 and multiply by the number of wires. Add them to get the total wire area. Find the conduit's internal area in Table 4 and multiply it by the Table 1 limit (53% for one wire, 31% for two, 40% for three or more). If the total wire area is no larger than that figure, the fill passes. The calculator on this page does all of this and also returns the smallest conduit that works.

Chapter 9, Table 1 allows wires to take up no more than 40% of a conduit's internal cross-sectional area when three or more conductors are installed. The limit is 53% for a single conductor and 31% for two conductors. The extra air space keeps heat down and makes pulling easier without damaging insulation.

Yes. Even though equipment grounding conductors (EGCs) do not carry current during normal operation (and thus are excluded from ampacity derating under §310.15(C)(1)), their physical cross-sectional area takes up space in the raceway and must be counted in Chapter 9 Table 1 conduit fill calculations.

Three #12 THHN (3 × 0.0133 in²) plus one #14 THHN (0.0097 in²) total 0.0496 in². That is within the 40% limit of 1/2-inch EMT, so 1/2-inch EMT is the smallest size that passes. Always check the result for your own wire mix in the calculator.

Four #10 THHN (4 × 0.0211 in²) plus one #12 THHN (0.0133 in²) total 0.0977 in². The smallest EMT that passes at 40% fill is 1/2-inch EMT. For three #4/0 THHN and a #2 ground the smallest EMT is 2-inch.

Use the insulation printed on your wire. Table 5 gives different areas for THHN/THWN-2 and XHHW/XHHW-2 (for example #12 is 0.0133 in² for THHN and 0.0181 in² for XHHW). Choosing the wrong one can make an overfilled conduit look compliant, so set the Insulation type field before you calculate.

Schedule 80 PVC is manufactured with extra-thick sidewalls to resist physical damage (§352.10(F)). Because the outside diameter is standard, the internal diameter and total cross-sectional area are substantially smaller than Schedule 40 PVC or thin-wall EMT.

Under Chapter 9, Table 1, Note 4, where conduit or tubing sections do not exceed 24 inches (600 mm) in length between enclosures, the maximum allowable fill is increased from 40% to 60%, and ampacity adjustment factors (derating) do not apply. Select "Yes" under Conduit nipple in the calculator to apply it.

Yes. Electricians often call conduit "pipe", so a pipe fill chart, conduit wire fill chart and NEC conduit fill chart all mean the same thing: the number of wires of one size allowed in each conduit trade size. The charts on this page cover EMT, PVC Schedule 40 and 80, rigid (RMC), IMC, ENT, FMC and LFMC.

At 40% fill, 4-inch conduit holds 8 500 kcmil THHN conductors in EMT, 7 in rigid (RMC), 7 in PVC Schedule 40 and 6 in PVC Schedule 80.

Inputs

Conductors in Conduit

Take this toolkit with you on the job

How it works & the NEC rules behind it

NEC Chapter 9 Table 1 Fill Rules:

Using the calculator

Related conduit guides

Formulas & equations

NEC reference table

Conduit fill chart: quick lookup by trade size (THHN/THWN-2)

Conduit wire fill chart: how many THHN/THWN-2 wires fit (40% fill)

EMT conduit fill chart (THHN wires per conduit)

PVC Schedule 40 conduit fill chart (THHN wires per conduit)

PVC Schedule 80 conduit fill chart (THHN wires per conduit)

Rigid (RMC) conduit fill chart (THHN wires per conduit)

IMC conduit fill chart (THHN wires per conduit)

ENT (flexible PVC) conduit fill chart (THHN wires per conduit)

Flexible metal conduit (FMC) fill chart (THHN wires per conduit)

Liquidtight (LFMC) conduit fill chart (THHN wires per conduit)

XHHW-2 conduit fill chart

EMT: XHHW-2 wires per conduit

PVC Schedule 40: XHHW-2 wires per conduit

RMC (rigid): XHHW-2 wires per conduit

Conduit fill area chart: 53%, 31%, 40% and 60% limits by size

Electrical Metallic Tubing (Art. 358)

Rigid Metal Conduit (Art. 344)

Intermediate Metal Conduit (Art. 342)

Rigid PVC Conduit, Schedule 40 / HDPE (Art. 352, 353)

Rigid PVC Conduit, Schedule 80 (Art. 352)

Electrical Nonmetallic Tubing (Art. 362)

Flexible Metal Conduit (Art. 348)

Liquidtight Flexible Metal Conduit (Art. 350)

Worked example, step by step

Frequently asked questions

How many wires can fit in a 1/2-inch conduit? −

How many #12 wires can fit in a 3/4-inch conduit? +

How do you calculate conduit fill? +

What is the 40% conduit fill rule? +

Does the ground wire count towards conduit fill percentage? +

What size EMT do I need for three #12 wires and a #14 ground? +

What conduit size is needed for four #10 wires and a #12 ground? +

Do I use THHN or XHHW for the calculation? +

Why does Schedule 80 PVC fit fewer wires than Schedule 40 PVC or EMT? +

What is the 24-inch conduit nipple exception? +

Is a pipe fill chart the same as a conduit fill chart? +

How many 500 kcmil wires fit in a 4-inch conduit? +

Related NEC calculators

Wire Gauge Calculator

Conductor Derating Calculator

Pull & Junction Box Sizing Calculator

Box Fill Calculator

Voltage Drop Calculator