How many 12 gauge wires fit in 1/2 inch conduit?

A 1/2 inch EMT conduit holds up to 9 THHN wires of 12 AWG at 40% fill (NEC 2023, Chapter 9 Table 1). The same trade size holds 8 wires in PVC Schedule 40, 6 in PVC Schedule 80 and 9 in rigid metal conduit (RMC).

12 AWG THHN wires in 1/2 inch conduit by conduit type

12 AWG THHN wires in 1/2 inch conduit at 40% fill
Conduit	Inside area, in²	12 AWG THHN wires
Electrical metallic tubing (EMT)	0.304	9
Rigid PVC conduit, Schedule 40	0.285	8
Rigid PVC conduit, Schedule 80	0.217	6
Rigid metal conduit (RMC)	0.314	9

How the 40% conduit fill is calculated

Wires = inside area × 40% ÷ area of one wire. One 12 AWG THHN wire is 0.0133 in². In 1/2 inch EMT: 0.304 in² × 40% ÷ 0.0133 in² = 9.14, rounded down unless the decimal is 0.8 or more, so 9 wires.

What else limits 12 AWG wires in 1/2 inch conduit

Half-inch conduit is the smallest common size and fills up quickly. Ground wires count toward the fill, and with more than three current-carrying conductors in one conduit their ampacity must be reduced.

The wire counts on this page are for THHN/THWN-2 insulation. PVC has a thicker wall than EMT, so the same trade size holds fewer wires.

Related wire size, circuit and conduit answers

Sources

NFPA 70, National Electrical Code (2023): Percent of cross section of conduit and tubing for conductors, Chapter 9 Table 1
NFPA 70, National Electrical Code (2023): Dimensions and percent area of conduit and tubing, Chapter 9 Table 4
NFPA 70, National Electrical Code (2023): Dimensions of insulated conductors, Chapter 9 Table 5

Compared with 4 published documents, last on 2026-11-13

Carlon / Thomas & Betts (ABB) (catalog (edition not stated)): General information: wire fill based on Chapter 9 Table 1 — Conduit fill percentages
Florida International University (course notes, NEC edition not stated): Chapter III, Electrical Wiring Components (Figure 3.18, area of THHN conductors) — THHN areas for 14 to 6 AWG; the larger sizes match a training reproduction of the same table
Southwire Company, Power Cable Installation Guide (2005 (cites 2005 NEC)): Dimensions and percent area of conduit and tubing, Table 8 (EMT, rigid PVC Schedule 40 and 80) — Fill percentages and internal areas of EMT, PVC Schedule 40 and Schedule 80
Wheatland Tube (2022): Rigid Metal Conduit Submittal Sheet, weights and dimensions — Rigid metal conduit inside diameters; the areas follow from them

Calculated by Calculate.diy with the method of the National Electrical Code® (NEC®), 2023 edition; not the NEC text. Methodology. For planning only: check local code and use a licensed electrician.