What is the maximum conduit fill percentage?

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

How many 12 AWG wires fit in 1/2 inch EMT?

Using nominal THHN dimensions and the 40% rule, 9 12 AWG THHN conductors fit in 1/2 inch EMT. Count every current-carrying conductor plus the equipment grounding conductor.

Does the ground wire count toward conduit fill?

Yes. Every conductor in the raceway counts for fill, including the equipment grounding conductor and the neutral. Grounds are excluded only from ampacity derating counts, not from fill.

Why does PVC Schedule 80 hold fewer wires?

Schedule 80 has the same outside diameter as Schedule 40 but a thicker wall, so the internal diameter and usable area are smaller. Expect roughly 15 to 25% fewer conductors for the same trade size.

Is more than 40% fill ever allowed?

Only for short nipples of 24 inches or less, which are permitted at 60% fill. Ordinary raceway runs stay at 40%, and exceeding it makes pulling difficult and traps heat around the conductors.

Conduit Fill Chart

Maximum conductor count per trade size, computed from published raceway internal diameters and nominal THHN outside diameters.

Quick answer

Fill limits are 40% of internal area for three or more conductors, 31% for two, 53% for one, and 60% for nipples 24 inches or shorter. In 1/2 inch EMT that works out to about 12 14 AWG, 9 12 AWG or 5 10 AWG THHN conductors. Grounds and neutrals count.

EMT fill chart — THHN/THWN-2

Maximum number of same-size conductors at the applicable fill percentage. Mixed sizes need the 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	12	22	35	61	84	138	242	365	401	401
12 AWG	9	16	26	45	61	101	176	266	347	401
10 AWG	5	10	16	28	38	63	110	167	218	279
8 AWG	3	5	9	16	22	36	63	96	126	161
6 AWG	1	4	6	11	16	26	46	69	91	116
4 AWG	1	2	4	7	9	16	28	42	56	71
3 AWG	1	1	3	6	8	13	24	36	47	60
2 AWG	1	1	2	5	7	11	20	30	39	50
1 AWG	1	1	1	3	5	8	14	22	29	37
1/0 AWG	—	1	1	3	4	7	12	19	24	31
2/0 AWG	—	1	1	2	3	6	10	15	20	26
3/0 AWG	—	1	1	1	3	5	8	13	17	22
4/0 AWG	—	—	1	1	1	4	7	10	14	18

EMT (electrical metallic tubing)

Published standard

Source & method: Counts are computed as floor(usable area / conductor area) with the fill percentage that matches the resulting count. Nothing is copied from a code table.

Raceway internal area by trade size

Trade size	EMT	IMC	RMC	PVC 40	PVC 80
1/2"	0.304 (0.122)	0.342 (0.137)	0.314 (0.125)	0.285 (0.114)	0.217 (0.087)
3/4"	0.533 (0.213)	0.586 (0.235)	0.549 (0.220)	0.508 (0.203)	0.409 (0.164)
1"	0.864 (0.346)	0.959 (0.384)	0.887 (0.355)	0.832 (0.333)	0.688 (0.275)
1-1/4"	1.496 (0.598)	1.647 (0.659)	1.526 (0.610)	1.453 (0.581)	1.237 (0.495)
1-1/2"	2.036 (0.814)	2.225 (0.890)	2.071 (0.829)	1.986 (0.794)	1.711 (0.684)
2"	3.356 (1.342)	3.631 (1.452)	3.408 (1.363)	3.291 (1.316)	2.874 (1.150)
2-1/2"	5.858 (2.343)	5.135 (2.054)	4.866 (1.946)	4.695 (1.878)	4.119 (1.647)
3"	8.846 (3.538)	7.922 (3.169)	7.499 (3.000)	7.268 (2.907)	6.442 (2.577)
3-1/2"	11.545 (4.618)	10.584 (4.234)	10.010 (4.004)	9.737 (3.895)	8.688 (3.475)
4"	14.753 (5.901)	13.631 (5.452)	12.883 (5.153)	12.554 (5.022)	11.258 (4.503)

Total internal cross-sectional area, square inches, and the 40% usable figure.

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

What is the maximum conduit fill percentage?: 40% of the conduit's internal cross-sectional area for three or more conductors, 31% for exactly two conductors and 53% for a single conductor. Nipples 24 inches or shorter are permitted at 60%.
How many 12 AWG wires fit in 1/2 inch EMT?: Using nominal THHN dimensions and the 40% rule, 9 12 AWG THHN conductors fit in 1/2 inch EMT. Count every current-carrying conductor plus the equipment grounding conductor.
Does the ground wire count toward conduit fill?: Yes. Every conductor in the raceway counts for fill, including the equipment grounding conductor and the neutral. Grounds are excluded only from ampacity derating counts, not from fill.
Why does PVC Schedule 80 hold fewer wires?: Schedule 80 has the same outside diameter as Schedule 40 but a thicker wall, so the internal diameter and usable area are smaller. Expect roughly 15 to 25% fewer conductors for the same trade size.
Is more than 40% fill ever allowed?: Only for short nipples of 24 inches or less, which are permitted at 60% fill. Ordinary raceway runs stay at 40%, and exceeding it makes pulling difficult and traps heat around the conductors.

Raceway and pulling supplies

Common trade sizes and pulling gear.

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EMT fill chart — THHN/THWN-2

Raceway internal area by trade size

Conductor outside diameters used

Frequently asked

Raceway and pulling supplies

Raceway and pulling supplies

Related charts & calculators