How many 4 AWG wires fit in 1/2 inch EMT?

1 4 AWG THHN conductors fit in 1/2 inch EMT at the applicable fill percentage.

How many 4 AWG wires fit in 3/4 inch EMT?

2 conductors, using a nominal THHN outside diameter of 0.324 in and the 40% fill rule for three or more conductors.

Do neutrals and grounds count toward fill?

Yes, every conductor in the raceway counts for fill. Grounds are excluded only from the count of current-carrying conductors used for ampacity adjustment.

What is the cross-sectional area of 4 AWG THHN?

About 0.0824 square inches, from A = π × (OD / 2)² with a nominal insulated OD of 0.324 in.

4 AWG Conduit Fill by Conduit Size

How many 4 AWG THHN conductors fit in EMT, IMC, RMC and PVC conduit, 1/2 inch through 4 inch, with the 40% fill rule applied.

Quick answer

1 4 AWG THHN conductors fit in 1/2 inch EMT and 2 fit in 3/4 inch EMT, at 40% fill for three or more conductors. Each conductor consumes 0.0824 sq in from a nominal insulated outside diameter of 0.324 in. Neutrals and grounds count.

4 AWG conductors per conduit trade size

Same-size conductors only, at 53% for one, 31% for two and 40% for three or more.

Conduit	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
EMT	1	2	4	7	9	16	28	42	56	71
IMC	1	2	4	7	10	17	24	38	51	66
RMC	1	2	4	7	10	16	23	36	48	62
PVC Sch 40	1	1	4	7	9	15	22	35	47	60
PVC Sch 80	1	1	3	6	8	13	19	31	42	54

Published standard

Source & method: Counts are the largest whole number where n × conductor area stays inside the raceway area times the applicable fill percentage. Mix conductor sizes in the calculator.

Fill behaviour at 4 AWG: feeder-scale raceway from here up

At 4 AWG, 1/2 inch tubing is out of the picture and 3/4 inch holds only a very small count. A 100 A feeder set of three conductors plus a grounding conductor typically requires 1 inch or 1-1/4 inch, and underground PVC of the same trade size holds fewer conductors than metal tubing because the wall is thicker.

This is also the size where the difference between conduit types starts to show clearly in the table above. Schedule 80 PVC loses noticeably more internal area than Schedule 40, and a run that fits in EMT may need the next trade size in Schedule 80 through an exposed or damage-prone location.

Source & method: Counts referenced above come from the computed table on this page — how these numbers are derived.

What each raceway type means

EMT — EMT (electrical metallic tubing)
IMC — IMC (intermediate metal conduit)
RMC — RMC (rigid metal conduit)
PVC Sch 40 — PVC Schedule 40
PVC Sch 80 — PVC Schedule 80

Full fill charts by raceway

Per-type counts for every trade size, plus the cross-type comparison and reverse lookup.

Frequently asked

How many 4 AWG wires fit in 1/2 inch EMT?: 1 4 AWG THHN conductors fit in 1/2 inch EMT at the applicable fill percentage.
How many 4 AWG wires fit in 3/4 inch EMT?: 2 conductors, using a nominal THHN outside diameter of 0.324 in and the 40% fill rule for three or more conductors.
Do neutrals and grounds count toward fill?: Yes, every conductor in the raceway counts for fill. Grounds are excluded only from the count of current-carrying conductors used for ampacity adjustment.
What is the cross-sectional area of 4 AWG THHN?: About 0.0824 square inches, from A = π × (OD / 2)² with a nominal insulated OD of 0.324 in.

Conduit fill for nearby sizes

Same 40% fill rule applied to the sizes either side of this one, wrapping around the range so every size is reachable.