Electrical metallic tubing (EMT) is a thin-wall metal raceway covered by NEC Article 358. It is different from intermediate metal conduit (IMC, Article 342), rigid metal conduit (RMC, Article 344) and PVC conduit (Article 352), and each has its own Table 4 dimensions. This page is limited to EMT, and the Conduit Fill Chart compares the raceway types.

Chapter 9 Table 1 sets the maximum share of the EMT’s internal cross-sectional area that conductors may occupy.

One Conductor: 53%

A single conductor may occupy 53% of the EMT area.

Two Conductors: 31%

Exactly two conductors are limited to 31%, not 40%.

More Than Two: 40%

Three or more conductors may occupy 40% of the area. These percentages refer to cross-sectional area, not diameter.

Actual Fill Percentage

Maximum Allowable Area

Mixed Conductor Area

• A(conductors), A(total): combined area of all conductors and cables (in²)
• A(EMT): total internal EMT area from Table 4 (in²)
• N(i): quantity of conductors of type i
• A(i): area of one conductor of type i from Table 5 (in²)
• F: permitted fill written as a decimal

1. Identify the EMT trade size.
2. Obtain the EMT internal area from Table 4.
3. List every conductor.
4. Identify the AWG or kcmil size and insulation type.
5. Include grounding and bonding conductors.
6. Obtain each conductor area from Table 5.
7. Sum the occupied area.
8. Apply the correct fill limit.
9. Compare occupied and permitted area.
10. Check ampacity separately.

Three 12 AWG THHN in 1/2″ EMT

Mixed Conductor Sizes

• Annex C: same-size conductor counts.
• Table 1: the permitted fill percentage.
• Table 4: the EMT raceway area.
• Table 5: the insulated conductor area.
• Compact-conductor data: Table 5A where compact conductors are used.

For same-size conductors, Chapter 9 Note 7 permits the next higher whole number when the calculation leaves a decimal of 0.8 or larger. It explains counts that would otherwise look one short.

That is the published 22 × 14 AWG THHN result. A second case is 6 AWG in 1-1/4-in. EMT: 0.5984 ÷ 0.0507 = 11.80, which rounds up to 12.

Two 6 AWG conductors carry the same asterisk noted under the main chart.

See the main chart for additional sizes.

Larger sizes share one section. Counts are for same-size THHN/THWN/THWN-2 conductors.

AWG identifies the conductor size but does not fix the overall insulated conductor area. The AWG dimensions themselves are in the Wire Gauge Chart. Do not apply THHN counts automatically to XHHW-2 or other constructions.

Because a 12 AWG XHHW conductor is 0.0181 in² against 0.0133 in² for THHN, fewer XHHW conductors fit in the same EMT.

Compact conductors are compressed so the voids between strands are virtually eliminated, which changes their overall dimensions and their occupied area. Choose the correct data: Table 5A for compact conductors instead of the standard Table 5 values. Standard conductor counts cannot automatically be transferred to compact conductors.

Grounding and Bonding Conductors

Installed equipment grounding and bonding conductors occupy physical raceway area and must be included in the fill calculation using their actual dimensions, whether insulated or bare (Chapter 9 Table 1 Note 3). Raceway fill is a different question from counting current-carrying conductors for ampacity adjustment.

Neutral and Spare Conductors

Any conductor physically installed in the EMT takes up area, whether it is a neutral or a spare, regardless of how other NEC calculations treat it. Whether a particular neutral counts as current-carrying for ampacity is a separate question that this page does not settle.

Chapter 9 Table 1 Note 4 allows a nipple not longer than 24 in. (600 mm) between boxes, cabinets and similar enclosures to be filled to 60% of its cross-sectional area. For 1/2-in. EMT: 0.304 × 0.60 = 0.1824 in².

A conduit can pass the fill check and still require ampacity adjustment for the number of current-carrying conductors.

Maximum fill does not decide whether a pull is practical. Pull length, the number of bends, conductor outside diameter, pulling tension, sidewall pressure and jamming all matter. Southwire’s professional tools report fill and jam probability separately, which shows that they are distinct checks.

Bends, pull points, fittings, support and avoiding damaged or deformed EMT all affect how well a run works. A crushed or kinked tube reduces the usable opening. Detailed bending and support requirements are outside this page’s scope.

The same trade size does not have the same internal area across raceway types. For 3/4-in. raceways, Table 4 lists:

For the full comparison of EMT, PVC, IMC, RMC and other raceways, use the Conduit Fill Chart, and see the PVC Conduit Fill Chart for PVC.

1. List the conductors.
2. Identify the insulation and construction.
3. Calculate the total occupied area.
4. Determine the applicable fill percentage.
5. Compare candidate EMT sizes.
6. Select a compliant trade size.
7. Check ampacity.
8. Consider bends and pulling conditions.
9. Verify the adopted NEC and AHJ requirements.

The smallest compliant EMT is not always the most practical installation choice.

The checker uses THHN/THWN/THWN-2 areas and a direct area comparison. Annex C may allow one more same-size conductor under the Note 7 rounding rule. Include grounding conductors, and use it for practice, not permit approval.