Conduit Fill Table | 3/4 EMT #12, #10 and #6

Source: NEC 2023, Chapter 9, Tables 1, 4 & 5 · Reviewed: 2026-06-07 · Fill limits: 53% (1 wire), 31% (2 wires), 40% (3+ wires).

Quick Reference: Wires per Conduit Size

THHN/THWN wire in EMT conduit — 40% fill (3 or more conductors, per NEC Chapter 9 Table C1):

Conduit Size	#14 AWG	#12 AWG	#10 AWG	#8 AWG	#6 AWG	#4 AWG
1/2" EMT	12	9	5	3	2	1
3/4" EMT	22	16	10	5	4	2
1" EMT	35	26	16	9	6	4
1-1/4" EMT	61	46	28	16	11	7
1-1/2" EMT	84	63	38	22	15	10
2" EMT	138	103	63	36	25	16

→ Use the Conduit Fill Calculator for quick single-size checks, then manually sum conductor areas from the adopted NEC tables for mixed-size raceways.

---

NEC Fill Percentage Rules

NEC Table 1 - Percent Fill

Number of Conductors	Allowable Fill %
1	53%
2	31%
3 or more	40%

Source: NEC Chapter 9, Table 1

Why Different Percentages?

• 1 wire (53%): Single conductor can "snake" through conduit
• 2 wires (31%): Two wires jam against each other, reducing usable space
• 3+ wires (40%): Multiple wires distribute more evenly, allowing more fill

---

Conduit Types and Sizes

Common Conduit Types

Type	Abbreviation	Wall	Use
Electrical Metallic Tubing	EMT	Thin	Indoor, commercial
Intermediate Metal Conduit	IMC	Medium	Indoor/outdoor
Rigid Metal Conduit	RMC	Thick	Outdoor, industrial
PVC Schedule 40	PVC-40	Medium	Underground, wet
PVC Schedule 80	PVC-80	Thick	Exposed, industrial
Flexible Metal Conduit	FMC	Flexible	Equipment connections
Liquidtight Flexible	LFMC	Flexible	Wet locations

Trade Size Reference

Trade Size	Actual OD	Common Use
1/2"	0.84"	Small circuits
3/4"	1.05"	Residential
1"	1.32"	Commercial
1-1/4"	1.66"	Commercial
1-1/2"	1.90"	Feeders
2"	2.38"	Large feeders
2-1/2"	2.88"	Industrial
3"	3.50"	Industrial
4"	4.50"	Service entrance

---

EMT Conduit Fill Tables

EMT Internal Area (NEC Table 4)

Trade Size	Total Area (in²)	40% Fill (in²)	31% Fill (in²)
1/2"	0.304	0.122	0.094
3/4"	0.533	0.213	0.165
1"	0.864	0.346	0.268
1-1/4"	1.496	0.598	0.464
1-1/2"	2.036	0.814	0.631
2"	3.356	1.342	1.040
2-1/2"	5.858	2.343	1.816
3"	8.846	3.538	2.742
4"	15.513	6.205	4.809

Maximum THHN/THWN Wires in EMT (40% Fill)

Wire Size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"
14 AWG	12	22	35	61	84	138
12 AWG	9	16	26	46	63	103
10 AWG	5	10	16	28	38	63
8 AWG	3	5	9	16	22	36
6 AWG	2	4	6	11	15	25
4 AWG	1	2	4	7	10	16
3 AWG	1	1	3	6	8	14
2 AWG	1	1	3	5	7	12
1 AWG	1	1	2	4	5	8
1/0	0	1	1	3	4	7
2/0	0	1	1	2	3	6
3/0	0	1	1	2	3	5
4/0	0	1	1	1	2	4

---

RMC (Rigid) Conduit Fill Tables

RMC Internal Area

Trade Size	Total Area (in²)	40% Fill (in²)
1/2"	0.314	0.126
3/4"	0.549	0.220
1"	0.887	0.355
1-1/4"	1.526	0.610
1-1/2"	2.071	0.829
2"	3.408	1.363
2-1/2"	4.866	1.946
3"	7.499	3.000
4"	12.882	5.153

Maximum THHN/THWN in RMC (40% Fill)

Wire Size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"
14 AWG	13	22	36	62	85	140
12 AWG	9	17	27	47	64	104
10 AWG	6	10	17	29	39	64
8 AWG	3	6	9	16	22	37
6 AWG	2	4	7	11	16	26
4 AWG	1	2	4	7	10	16
2 AWG	1	1	3	5	7	12
1/0	0	1	1	3	4	7
4/0	0	1	1	1	3	4

---

PVC Conduit Fill Tables

PVC Schedule 40 Internal Area

Trade Size	Total Area (in²)	40% Fill (in²)
1/2"	0.285	0.114
3/4"	0.508	0.203
1"	0.832	0.333
1-1/4"	1.453	0.581
1-1/2"	1.986	0.794
2"	3.291	1.316
2-1/2"	4.695	1.878
3"	7.268	2.907
4"	12.554	5.022

PVC Schedule 80 (Thicker Wall - Less Fill)

Trade Size	Total Area (in²)	40% Fill (in²)
1/2"	0.217	0.087
3/4"	0.409	0.164
1"	0.688	0.275
1-1/4"	1.237	0.495
1-1/2"	1.711	0.684
2"	2.874	1.150

---

Conduit Type Comparison: EMT vs RMC vs PVC

Maximum #12 AWG THHN conductors at 40% fill (3+ wires) — same trade size, different conduit types:

Trade Size	EMT	RMC	PVC Sch.40	PVC Sch.80
1/2"	9	9	8	6
3/4"	16	17	15	12
1"	26	27	25	20
1-1/4"	46	47	43	37
1-1/2"	63	64	59	51
2"	103	104	98	86

Key takeaway: EMT and RMC hold nearly identical counts. PVC Schedule 40 is ~5% less than EMT; PVC Schedule 80 is ~15% less due to the thicker wall reducing internal area.

---

Wire Area Reference

THHN/THWN Wire Areas (NEC Table 5)

Wire Size	Area (in²)	Wire Size	Area (in²)
14 AWG	0.0097	1 AWG	0.1562
12 AWG	0.0133	1/0	0.1855
10 AWG	0.0211	2/0	0.2223
8 AWG	0.0366	3/0	0.2679
6 AWG	0.0507	4/0	0.3237
4 AWG	0.0824	250 kcmil	0.3970
3 AWG	0.0973	300 kcmil	0.4608
2 AWG	0.1158	350 kcmil	0.5242

XHHW Wire Areas

Wire Size	Area (in²)	Wire Size	Area (in²)
14 AWG	0.0139	1 AWG	0.1901
12 AWG	0.0181	1/0	0.2223
10 AWG	0.0278	2/0	0.2624
8 AWG	0.0437	3/0	0.3117
6 AWG	0.0590	4/0	0.3718
4 AWG	0.0934	250 kcmil	0.4536
2 AWG	0.1333	300 kcmil	0.5281

---

Conduit Fill Calculation Steps

Step-by-Step Process

1. List all conductors going in the conduit
2. Find wire area for each conductor (NEC Table 5)
3. Sum total wire area
4. Determine fill percentage (1, 2, or 3+ wires)
5. Calculate required conduit area: Total Wire Area ÷ Fill %
6. Select conduit size with area ≥ required

Calculation Formula

Required Conduit Area = Total Wire Area / Fill Percentage

Where Fill Percentage:
- 1 conductor: 0.53
- 2 conductors: 0.31
- 3+ conductors: 0.40

---

Worked Examples

Example 1: Residential Branch Circuit

Given: 3 × #12 AWG THHN conductors

Solution:

1. Wire area: 12 AWG THHN = 0.0133 in²
2. Total area: 3 × 0.0133 = 0.0399 in²
3. Fill percentage: 3 wires = 40%
4. Required area: 0.0399 / 0.40 = 0.0998 in²
5. Select conduit: 1/2" EMT (0.122 in² at 40%) ✓

Answer: Use 1/2" EMT

Example 2: Commercial Feeder

Given: 3 × #4 AWG + 1 × #8 AWG ground (THHN)

Solution:

1. Wire areas:

• 3 × #4 AWG = 3 × 0.0824 = 0.2472 in²
• 1 × #8 AWG = 0.0366 in²
• Total = 0.2838 in²

2. 4 conductors = 40% fill
3. Required area: 0.2838 / 0.40 = 0.7095 in²
4. Select: 1-1/4" EMT (0.598 in²) - NO
5. Next size: 1-1/2" EMT (0.814 in²) ✓

Answer: Use 1-1/2" EMT

Example 3: Industrial Three-Phase

Given: 3 × 3/0 AWG + 1 × #4 AWG ground (THHN)

Solution:

1. Wire areas:

• 3 × 3/0 AWG = 3 × 0.2679 = 0.8037 in²
• 1 × #4 AWG = 0.0824 in²
• Total = 0.8861 in²

2. 4 conductors = 40% fill
3. Required area: 0.8861 / 0.40 = 2.215 in²
4. Select conduit:

• 2" EMT = 1.342 in² - NO
• 2-1/2" EMT = 2.343 in² ✓

Answer: Use 2-1/2" EMT

Example 4: Mixed Wire Sizes

Given: 6 × #12 AWG + 3 × #10 AWG (THHN)

Solution:

1. Wire areas:

• 6 × #12 = 6 × 0.0133 = 0.0798 in²
• 3 × #10 = 3 × 0.0211 = 0.0633 in²
• Total = 0.1431 in²

2. 9 conductors = 40% fill
3. Required area: 0.1431 / 0.40 = 0.3578 in²
4. Select: 1" EMT (0.346 in²) - Close, use next size
5. Use: 1-1/4" EMT (0.598 in²) ✓

Answer: Use 1-1/4" EMT (or verify 1" is acceptable)

---

Special Considerations

Equipment Grounding Conductor

• Include EGC in fill calculation
• Same insulation type as circuit conductors
• Size per NEC 250.122

Nipples (24" or Less)

For short conduit runs ≤24":

• 60% fill allowed (instead of 40%)
• Applies to straight runs only

Over 2 Conductors of Same Size

When all conductors are same size and type:

• Use NEC Annex C tables directly
• No calculation needed

---

Common Mistakes to Avoid

Mistake	Why It's Wrong	Correct Approach
Forgetting ground wire	Underestimates fill	Include all conductors
Using 40% for 2 wires	Should be 31%	Check wire count first
Mixing conduit types	Different internal areas	Use correct table
Ignoring insulation type	Different wire ODs	Use correct wire area

---

Related Calculators

Calculator	Use When...
Conduit Fill Calculator	Quick conduit sizing
Wire Size Calculator	Selecting wire gauge
Voltage Drop Calculator	Long distance runs
Box Fill Calculator	Junction box sizing

---

Summary

Key Fill Percentages:

• 1 conductor: 53%
• 2 conductors: 31%
• 3+ conductors: 40%

Calculation:

Required Area = Total Wire Area / Fill %

Always:

1. Include ground conductor
2. Use correct insulation type area
3. Use matching conduit type table
4. Round up to next standard size

---

FAQ

How many wires can I put in a 1/2" EMT?

Depends on wire size and type. For THHN: 12 × #14, 9 × #12, or 5 × #10 AWG maximum at 40% fill. Always verify with proper calculation.

What's the difference between EMT and rigid conduit fill?

RMC (rigid) has thicker walls, so slightly less internal area than same trade size EMT. The difference is small but matters for tight fills.

Do I count the ground wire in conduit fill?

Yes, always include the equipment grounding conductor (EGC) in your fill calculation. It takes up space just like circuit conductors.

Can I exceed 40% fill?

Only in specific cases: nipples (≤24") allow 60%, and bare wire calculations may allow more. Otherwise, 40% is the maximum for 3+ conductors per NEC.

Why is 2-wire fill only 31%?

Two wires tend to lie alongside each other in the conduit, creating a "jamming" effect that reduces the usable space. The 31% accounts for this inefficiency.

How many #12 wires fit in 3/4" EMT?

16 wires of #12 AWG THHN at 40% fill (3 or more conductors), per NEC Chapter 9 Table C1. This is one of the most common conduit fill scenarios in residential and commercial wiring. For exactly 2 conductors, the 31% fill rule limits the count to 12.

What conduit size for 4 × #10 AWG wires?

4 × #10 AWG THHN → total wire area = 4 × 0.0211 in² = 0.0844 in². Required conduit area at 40% fill = 0.0844 / 0.40 = 0.211 in². Answer: 3/4" EMT (0.213 in² at 40%) is the minimum size that satisfies NEC Chapter 9 fill requirements.

How many #10 wires fit in 1" EMT?

16 wires of #10 AWG THHN fit in 1" EMT at 40% fill (3 or more conductors), per NEC Chapter 9 Table C1.