EMT Conduit Fill Chart

Electrical Metallic Tubing — NEC Article 358. Thin-wall galvanized steel tubing joined with set-screw or compression fittings. The default raceway for commercial branch circuits and exposed indoor work.

1/2-inch EMT holds 9 #12 THHN conductors; 3/4-inch holds 16. Counts assume 40% fill with all conductors the same size.

EMT fill calculator

Conduit type

Trade size

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

Loading calculator…

EMT sizes

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

EMT 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 EMT — 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"
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	1	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	3	4	7	12	19	25	32
2/0 AWG	—	1	1	2	3	6	10	16	20	26
3/0 AWG	—	1	1	1	3	5	8	13	17	22
4/0 AWG	—	—	1	1	1	4	7	11	14	18
250 kcmil	—	—	1	1	1	3	6	9	11	15
300 kcmil	—	—	—	1	1	3	5	7	10	13
350 kcmil	—	—	—	1	1	1	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	2	4	5	7
700 kcmil	—	—	—	—	1	1	1	3	4	6
750 kcmil	—	—	—	—	1	1	1	3	4	5
800 kcmil	—	—	—	—	—	1	1	3	4	5
900 kcmil	—	—	—	—	—	1	1	3	3	4
1000 kcmil	—	—	—	—	—	1	1	2	3	4

EMT 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 EMT — 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"
14 AWG	8	15	25	43	58	96	168	254	332	424
12 AWG	6	11	19	33	45	74	129	195	255	326
10 AWG	5	8	14	24	33	55	96	145	190	243
8 AWG	2	5	8	13	18	30	53	81	105	135
6 AWG	1	3	6	10	14	22	39	60	78	100
4 AWG	1	2	4	7	10	16	28	43	56	72
3 AWG	1	1	3	6	8	14	24	36	48	61
2 AWG	1	1	3	5	7	11	20	31	40	51
1 AWG	1	1	1	4	5	8	15	23	30	38
1/0 AWG	—	1	1	3	4	7	13	19	25	32
2/0 AWG	—	1	1	2	3	6	10	16	21	27
3/0 AWG	—	1	1	1	3	5	9	13	17	22
4/0 AWG	—	—	1	1	1	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	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	2	4	5	6
700 kcmil	—	—	—	—	1	1	1	3	4	6
750 kcmil	—	—	—	—	1	1	1	3	4	5
800 kcmil	—	—	—	—	—	1	1	3	4	5
900 kcmil	—	—	—	—	—	1	1	3	3	4
1000 kcmil	—	—	—	—	—	1	1	2	3	4

EMT 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 EMT — 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"
14 AWG	8	15	25	43	58	96	168	254	332	424
12 AWG	6	11	19	33	45	74	129	195	255	326
10 AWG	5	8	14	24	33	55	96	145	190	243
8 AWG	2	5	8	13	18	30	53	81	105	135
6 AWG	1	3	4	8	11	18	32	48	63	81
4 AWG	1	1	3	6	8	13	24	36	47	60
3 AWG	1	1	3	5	7	12	20	31	40	52
2 AWG	1	1	2	4	6	10	17	26	34	44
1 AWG	—	1	1	3	4	7	12	18	24	31
1/0 AWG	—	1	1	2	3	6	10	16	20	26
2/0 AWG	—	1	1	1	3	5	9	13	17	22
3/0 AWG	—	—	1	1	2	4	7	11	15	19
4/0 AWG	—	—	1	1	1	3	6	9	12	16
250 kcmil	—	—	—	1	1	3	5	7	10	13
300 kcmil	—	—	—	1	1	1	4	6	8	11
350 kcmil	—	—	—	1	1	1	4	6	7	10
400 kcmil	—	—	—	1	1	1	3	5	7	9
500 kcmil	—	—	—	1	1	1	3	4	6	7
600 kcmil	—	—	—	—	1	1	1	3	4	6
700 kcmil	—	—	—	—	—	1	1	3	4	5
750 kcmil	—	—	—	—	—	1	1	3	4	5
800 kcmil	—	—	—	—	—	1	1	3	3	5
900 kcmil	—	—	—	—	—	1	1	2	3	4
1000 kcmil	—	—	—	—	—	1	1	1	3	4

EMT 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 EMT — 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"
14 AWG	4	7	11	20	27	46	80	120	157	201
12 AWG	3	6	9	17	23	38	66	100	131	167
10 AWG	2	5	8	13	18	30	53	81	105	135
8 AWG	1	1	4	7	9	16	28	42	55	70
6 AWG	1	1	3	5	8	13	22	34	44	56
4 AWG	1	1	2	4	6	10	17	26	34	44
3 AWG	1	1	1	4	5	9	15	23	30	38
2 AWG	—	1	1	3	4	7	13	20	26	33
1 AWG	—	1	1	1	3	5	9	13	17	22
1/0 AWG	—	—	1	1	2	4	7	11	15	19
2/0 AWG	—	—	1	1	1	4	6	10	13	17
3/0 AWG	—	—	1	1	1	3	5	8	11	14
4/0 AWG	—	—	—	1	1	3	5	7	9	12
250 kcmil	—	—	—	1	1	1	3	5	7	9
300 kcmil	—	—	—	1	1	1	3	5	6	8
350 kcmil	—	—	—	1	1	1	3	4	6	7
400 kcmil	—	—	—	—	1	1	2	4	5	7
500 kcmil	—	—	—	—	1	1	1	3	4	6
600 kcmil	—	—	—	—	—	1	1	3	4	5
700 kcmil	—	—	—	—	—	1	1	2	3	4
750 kcmil	—	—	—	—	—	1	1	1	3	4
800 kcmil	—	—	—	—	—	1	1	1	3	4
900 kcmil	—	—	—	—	—	1	1	1	3	3
1000 kcmil	—	—	—	—	—	1	1	1	2	3

EMT internal diameter and area

EMT 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	0.622	0.304	0.161	0.094	0.122	0.182
3/4"	21	0.824	0.533	0.282	0.165	0.213	0.320
1"	27	1.049	0.864	0.458	0.268	0.346	0.518
1-1/4"	35	1.380	1.496	0.793	0.464	0.598	0.898
1-1/2"	41	1.610	2.036	1.079	0.631	0.814	1.222
2"	53	2.067	3.356	1.779	1.040	1.342	2.014
2-1/2"	63	2.731	5.858	3.105	1.816	2.343	3.515
3"	78	3.356	8.846	4.688	2.742	3.538	5.308
3-1/2"	91	3.834	11.545	6.119	3.579	4.618	6.927
4"	103	4.334	14.753	7.819	4.573	5.901	8.852

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 EMT?

9 conductors of 12 AWG THHN/THWN-2, or 6 of the thicker THW. In 3/4-inch EMT the count rises to 16 THHN.

How many #10 wires fit in 1/2-inch EMT?

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

What is the inside diameter of 3/4-inch EMT?

0.824 inches, giving a total internal area of 0.533 in² and 0.213 in² of usable area at 40% fill.

What is the largest wire that fits in 4-inch EMT?

4-inch EMT holds 8 conductors of 500 kcmil THHN or 4 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.