4" IMC conduit fill

4" Intermediate metal conduit has an inside area of 13.631 sq in (4.166 in across). Three or more wires may take 40 % of it: 5.4524 sq in.

One wire, 53 %: 7.2244 sq in
Two wires, 31 %: 4.2256 sq in
Three or more, 40 %: 5.4524 sq in
Nipple, 60 %: 8.1786 sq in
Support: Every 10 ft, 3 ft from boxes
Sold in: 10 ft sticks

29 #1/0 THHN, the most it may hold, drawn to scale

How many wires fit in 4" IMC

All wires the same size and type, by Annex C's method. For a mix of sizes, open the calculator.

Wire size	THHN/THWN-2	XHHW-2	THW/THW-2
14 AWG	562	392	392
12 AWG	410	301	301
10 AWG	258	224	224
8 AWG	149	124	124
6 AWG	107	92	75
4 AWG	66	67	56
3 AWG	56	56	48
2 AWG	47	47	41
1 AWG	35	35	28
1/0 AWG	29	30	24
2/0 AWG	24	25	20
3/0 AWG	20	20	17
4/0 AWG	17	17	14
250 kcmil	13	14	12
300 kcmil	12	12	10
350 kcmil	10	10	9
400 kcmil	9	9	8
500 kcmil	7	8	7
600 kcmil	6	6	5
700 kcmil	5	5	5
750 kcmil	5	5	4
800 kcmil	5	5	4
900 kcmil	4	4	4
1000 kcmil	4	4	3

Smaller: 3-1/2" IMC

Other 4" conduit

Conduit	Inside area	#14	#12	#10	#8	#6
Intermediate metal conduit	13.631	562	410	258	149	107
Electrical metallic tubing	14.753	608	443	279	161	116
Rigid metal conduit (RMC, GRC)	12.882	531	387	244	140	101
Rigid PVC conduit, Schedule 40	12.554	517	377	238	137	99
Rigid PVC conduit, Schedule 80	11.258	464	338	213	123	89
Flexible metal conduit (FMC, Greenfield)	12.566	518	378	238	137	99
Liquidtight flexible metal conduit (LFMC)	12.692	523	381	240	138	100

About IMC

IMC has a thinner wall than rigid, so it has a little more room inside size for size. Support follows 342.30: within 3 ft of each box, then every 10 ft, or longer on straight runs with threaded couplings. See strap spacing and the fill rules.